CA1175575A - Programmable controller with multiple functions - Google Patents

Abstract

Abstract of the Disclosure A programmable controller includes a memory which stores an I/O image table and a data table. An I/O scanner module updates the I/O image table with the status of I/O devices connected to the programmable controller. The processor executes a control program to perform logical and arithmetic operations on the data in the data table. Such operations may be performed on data of different types and any necessary data conversions are performed automatically. Also, such operations may be performed on entire data files without degrading the response time of the program-mable controller.

Description

1:~ .` 5~5 Programmable Controller With ~ultiple Fun~tions The field of th~ in~ention is programmable controilers such as those described in U. S. Patent Nos. 3,810,118; 3,942,158; and 4,165,534.
Programmable controllers are typically connected to indus-trial e~uipment such as assembly lines and machine tools to sequentially operate the equipment in accordance with a stored program. In programmabLe controllers such as those disclosed in the above cited patents, for example, the control program is stored in a memory and includes instructions which are read out in rapid sequence to examine the condition of selected sensing devices on the controlled equipment and instructions which energize or deenergize selected operating devices on the con-trolled equipment contingent upon the status of one or more of the examined sensing devices.
The processor in a programmable controller is designed to rapidly execute programmable controller type instructions, which for the most part call for the manipulation of single-bit input data and the control of single-bit output data. The length of the control program, and hence the complexity of the system to be controlled, must be limited to insure that the entire control program can be executed, or scanned, within a set time. Such time limits are required to insure that the programmable con-troller will provide virtually instantaneous response to any change in the status of sensing devices on the controlled system.
Therefore, the speed with which a controller processor -an exe-cute programmable controller instructions hds a direct bearing on the size of the machine or process which it can effectively control.
In addition to the more conventionai programmable controlier instructions, there is an increasing need for an expanded in-structi.on set which will enable programmable control'ers ~o i~75~7S

perform functlons hitherto associated with general purpose com-puters. This is particularly true of large programmable con-trollers which are capable of controlling more than one indus-trial process, gathering management data, and generating management reports. It is important, however, that such func-tions not degrade the response time of the controller.
Another requirement of programmable controllers is that they be flexible in terms of the number and types of I/O devices with which they will operate. There are numerous types of input devices available ranging from simple switches to a variety of analog to digital converter devices. Similarly, output devices range from simple lights and solenoids to a wide variety of digital to analog conversion devices. There is a wide range of lS protocols, and data types associated with such I/O devices and the user should be provided with the m~ans for using these devices without special hardware interface circuits and complex data conversion requirements.
The present invention relates to a progra~nable controller with an expanded instruction set, and particularly, a program-mable controller which performs file manipulation unctions without significantly degrading controller response time, ~nd which conveniently performs arithmetic and logic functions on a wide variety of data types.
2S More specifically, the programmable controller includes: an I/O image table which stores data input from various input devices and output data which is output to various devices; a data tahle for storing in separate se~nents data of various types; and processor means which operates in response to instructions in a stored control program to move data between the I~O imaye table and the data table without data conversion and to perform logi^al and arithrnetic functions on data in the data table by converting data read from the data table to a native data type, performing 117~5~5 the indicated function, converting the result from the native data type to the proper data type and writing it into the data table. Another aspect of the invention is the ability to store data in the data table as a file comprised of more than one memory word, and the processor is operable in response to control program instructions to perform logic and arithmetic functions on an entire file.
The invention will enable one to provide a programmable controller with a powerful instruction set which is easy to program. The instruction set includes many logic and arithmetic functions which are executed by the processor and which operate on data stored in the data table. The user may write a program using these instructions without regard to the data type, since any necessary conversion of data is automatically performed both before the function is performed and afterwards. Thus, arithme-tic functions may be performed on data of two different types and the result stored in the data table in a third type. Eor example, a binary integer may be added to a binary coded decimal integer and the result stored as a floating point binar~ number.
All necessary data conversions are done automatically and are "transparent" to the user.
The invention will also enable one s to increase the speed at which control instructions can be executed. Control instruc-tions which operate on data files are included in the instruction set and these may be executed in segments such that their execu-tion time is spread over a number of scans through the control program. The CPU module also includes means for measuring the control program scan time so that the effects of control program editing can be immediately determined and the size of the seg-ments executed during each program scan can be altered ifrequired.

7~

According to a first broad aspect of the present invention, there is provided in a programmable controller which inputs data of various types from sensing devices connected to it and performs operations on such data in response to in-structions in a stored control program, the improvement therein comprising: a data table having a plurality of sections, each of which stores data of a particular type; means responsive to instructions in the control program for storing the input data from sensing devices in the data table section which stores the same data type; means for executing instructions in the control program which includes means for converting source data read from a data table section to a native data type, means for performing operations on the converted source data, and means for converting the data resulting from an operation to the data type of a destination data table section.
According to a second broad aspect of the present inventio~ there is provided in a programmable controller having a processor which reads instructions from a control program and executes them to examine the state of input devices and control the state of output devices, the improvement which comprises: memory means connected to the processor for storing a data table having a plurality of sections, each section stor-ing a specific data type; wherein said processor includes means for addressing sections of said data table and means for read-ing data from and writing data to addressed sections of the data table and means for converting the data type read from one section into the data type of other sections such that processing of data in the data table is accomplished with auto-matic conversion of data types.
According to a third broad aspect of the present invention, there is provided a programmable controller which comprises: a data table for storing data of different types in respective data table sections; memory means for storing a control program which includes arithmetic instructions that operate on data in different data table sections; and a proces-sor for sequentially reading the control program instructions from the memory and operating upon data stored in the data table, the processor including: (a) means responsive to a source operand address associated with an arithmetic instruction read from the memory means, for reading data from an indicated data table section and converting it to a native data type; (b) means responsive to the last named means and to an operation code associated with an arithmetic instruction read from the memory means, for performing the indicated arithmetic function on source data which has been converted to the native data type; and (c) means responsive to the last named means, and to a destination operand address associated with an arithmetic instruction read from the memory means, for converting the data which results from the arithmetic operation from the native data type to the data type of the data table section indicated by the destination operand address and for writing the conver-ted data to the indicated data table section.
According to a fourth broad aspect of the present invention, there is provided in a programmable controller hav-ing a processor which continuously and repeatedly scans and executes instructions in a stored control program to input data from sensing devices, perform logical operations on such data, and output the data which results from such logical oper-ations to operating devices, the improvement therein comprising:
means forming part of the processor for executing file instruc-tions which form part of the control program and which requireoperation on data files comprised of a plurality of separately ~7~ S

addressable data elements including: (a) detector means for detecting the presence of a code in a file instruction read from the control program which indicates that the file opera-tion is to be carried out in a distributed mode; (b) rate means coupled to the detector means for detecting the presence of another code in the file instruction which indicates the number of file data elements to be operated upon during each scan through the control program;(c) counter means for storing an indication of the file data elements which have been operated upon; (d) operation means coupled to the counter means and the rate means for performing an operation on an indicated number of file data elements which have not been operated upon;
and (e) means coupled to the counter means and the operation means for detecting when all file data elements have been oper-ated upon; wherein operations on data files may be performed over a plurality of scans through the control program to thereby distribute their execution time.
According to a fifth broad aspect of the present invention, there is provided in a programmable controller which stores a control program comprised of a series of control in-structions that direct a processor to examine the state of input devices and operate output devices, and in which the processor repeatedly and continuously scans the control program to provide prompt responses to changes in the states of input devices, the improvement comprising: addressable storage means coupled to the processor for storing a data file comprised of a plurality of separately addressable lines; and means asso-ciated with said processor for executing a file control instruc-tion in said control program that directs a function to be performed on said data file, said executing means comprising:
(a) means for reading a rate number in said file control inst-~17~75 ruetion; (b) means for storing said rate number; (c) meansfor performing the funetion indicated by said file control instruction during each scan through the control program on suceessive portions of said data file, and wherein the number of lines in eaeh portion is determined by the stored rate num-ber.

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In drawings which illustrate the embodiments of the inven-tion:
Fig. l is a block diagram of the programmable controller of the present invention;
Fig. 2 is a block diagram of the CPU module which forms part of Fig. 1;
Figs. 3A-3D are electrical schematic diagrams of the proces-sor interface circuit which orms part of the circuit of Fig. 2;
Fig. 4 is an electrical schematic diagram of the time base and watchdog timer which forms part of the circuit of Fig. 2;
Figs. 5A and 5B are a chart of the CPU module microfields;
Fig. 6 is an electrical schematic diagram of the interrupt interface circuit which forms part of the circuit of Fig. 2;
Fig. 7 is a block diagram of the I/O interface module which lS forms part of the system of Fig. 1;
Fig. 8 is a flow chart of the functions performed by the CPU
module of Fig. l;
Figs. 9A-9D are schematic representations of data structures which form a part of the memory module in Fig. l;
Figs. lOA-lOE and 11-13 are schematic representations of data structures which are employed to execute selected control program instructions;
Figs. 14A, 14B, and 14C are charts illustrating the func-tions performed by the I/O scanner module of Fig. 1;
Fig. 15 is a timing diagram which illustrates a write cycle and a read cycle on the system backplane bus which forms part of the system of Eig. l;
Fig. 16 is a schematic representation of a portion of the system of Fig. l used to describe the communication of messages between modules connected to the system backplane bus;

S

Fig. 17 is a flow chart which illustrates the execution of an arithmetic or logic instruction by the processor module of Fig. 2;
Fig. 18 is a flow chart which illustrates the execution of S the wordstart microroutine which forms part of the flow chart of Fig. 17;
Fig. l9 is a flow chart which illustrates the execution of the wordfinish microroutine which forms part of the flow chart of Eig. 17;
Fig. 20 is a schematic representation of the flow of data and the conversions that are performed on such data by the processor module of Fig. 2;
Fig. 21 is a flow chart which illustrates the execution of the filestart microroutine which forms part of the flow chart of Fig. 17;
Fig. 22 is a flow chart which illustrates the execution of the filefinish microroutine which forms part of the flow chart of Fig. 17; and Fig. 23 is a schematic representation of a pointer table which is employed by the processor module during the execution of arithmetic and logic instructions as illustrated in Fig. 17.

117~75 Ref~rring to Fig. l, the programmable controller includes a number of functionally oriented modules which communicate with each other over a high-performance system backplane bus 1. The system backplane bus 1 includes 16 bidirectional data lines (D0-D15), 26 address lines (A1-A26), and a number of control lines which are employed to signal the transfer of data and to perform bus arbitration and other functions. All of the modules except a memory module 2 are potential masters of the system backplane bus 1 and each can control read and write functions on the bus l. The backplane bus 1 is physically formed on a mother-board and the various system modules plug into edge connectors which attach to the bus leads and which form "slots" that mechanically support the module circuit boards.
There are a number of different functional modules which may be connected to the system backplane bus l. These modules need not be present in every system, and indeed, one advantage of this architecture is that the programmable controller can be con-figured to a particular control function by selection of the proper type and number of modules. In addition, to the memory module 2, the programmable controller described herein includes a CPU module 3, a communications network interface module 4, a peripheral processor module 5, a system I/O bus interface module 6,a system I/O scanner module 7 and a front panel 11. Most of the modules are allocated an address space of 256K and, with the exception of the CPU module 3, all modules may be duplicated in the system.
The memory module 2 contains from 4095 (~K) to 32,768 (32K) words of storage capacity. Each word contains 16-bits of data and one error detection bit. The module 2 occupies one slot in the system backplane bus 1, however, more than one memory module

2 may be used. The memory module 2 stores the user control program which is comprised of a set of macroinstructions that are executed to perform the desired control functions. The macro-instruction set includes conventional programmable controller instructions, arithmetic instructions and logic instructions, as well as many newly-defined instructions which employ the unique architecture of this programmable controller. The macroinstruc-tion set is described in detail hereinafter in connection with the description of the CPU module 3.
The user control program is loaded into the memory module 2 and edited using a terminal 8 which is shown connected to the peripheral processor module 5, but which also may connect to the system I/O scanner module 7. The terminal 8 includes a keyboard having keys labeled with the proper instruction set mnemonics and a display which presents the control program in rung diagram format. A terminal such as that described in U.S. Patent No.
4,326,193 is employed.
The communications network interface module 4 connects the programmable controller to a high speed data highway 9 which connects to other programmable controllers and computers in a network. Indeed, it may be a primary function of the program-mable controller of the present invention to perform supervisorycontrol operations in a distributed control system. The communi-cations network interface 4 is microprocessor based and it func-tions to interface the network communication protocol with the system backplane bus protocol. For a detailed description of the communications network protocol and hardware interface, reference is made to U.S. Patent No. 4,319,338, issued on March 9, 1982, and entitled "Industrial Communications Network".
The peripheral processor 5 is a microcomputer system which provides interface capability with up to four peripheral devices through serial data links. In addition to the programming s~

terminal 8, the peripheral processor may communicate with devlces such as printers and teletypes, and with other computers, either directly or through modems. The peripheral processor 5 services each serial I/O port and communicates through the backplane bus 1 with other modules. For example, control program data entered from the terminal 8 is interpreted by the module 5 and written into the memory module 2. Or, if an editing function is input at the terminal 8, the peripheral processor 5 may perform a number of read and write cycles to shift portions of the control program in the memory module 2.
The system I/O bus interface module 6 provides a high per-formance interface between the system backplane bus 1 and a system I/O bus 10. The I/O bus interface module 6 includes a random access memory which stores an image of the I/O system input and output points. Changes in the state of input points in the I/O system are received by the interface module 6 from one of the thirty-two possible I/O scanner circuits attached to the system I/O bus 10. The module 6 updates the state of its own I/O
image in the RAM and then obtains control of the backplane bus 1 2Q and trans~ers this information to an I/O image and data table stored in a processor read/write memory 12 located in the CPU
module 3, or to an I/O image and data table 623 in the memory module 2. In addition to the exchange of I/O data which reflects state changes in I/O points, the interface module 6 also performs a periodic "refresh" scan of all I/O points in the system. By this method, the integrity of the state of the I/O image and data table in memory 12 ls insured as well as all output points in the I/O system.
Up to 32 separate I/O scanners or instrumentation interface circuits may be attached to the system I/O bus 10, and with these, up to 4096 input points and 4096 output points may be serviced by the programmable controller without degrading its ~7~57S

response time. In the preferred embodiment shown in Fig. 1 only a single parallel I/0 scanner 13 and a serial I/0 scanner 14 are shown. Up to 32 separate I/0 racks 16 may be attached to each of these scanners 13 or 14, and each I/O rack 16 contains ar adapter circuit 17 which interfaces with one or more I/O modules.
The I/0 modules in each rac~ 16 contain circuitry which connects the programmable controller to the machine being con-trolled. These include input circuits such as those disclosed in U.S. Patent Nos. 3,643,115 and 4,275,307 which sense the opening and closing of switches. This circuitry also includes output circuits such as that disclosed in U.S. patent No. 3,745,546 which may be employed to control motors and solenoids. Although a vast majority of these modules are single-bit oriented, word oriented modules such as analog-to-digital and digital-to-analog converter modules disclosed in U.S. Patent No. 4,104,731 may also be employed. Physically, the I/O racks 16 may take a number of orms as disclosed in U.S. patent ~Jos. 3,992,654; 4,151,580 and 4,152,750.
The system I/0 scanner module 7 serves much the same purpose as the system I/0 bus interface module 6, but on a smaller scale.
Indeed, in smaller systems it may be the only I/0 interface module employed. The system I/0 scanner module 7 is micro-processor-based and it includes four serial ports which may be software configured to drive a number of components. In the preferred embodiment shown in Fig. 1, it is configured to com-municate with four I/0 racks 16 through their respective adapter circuits 17, but on smaller systems one port may be employed to communlcate with the programming terminal 8.
The front panel module 11 provides a convenient, but rather limited means for manually entering data into the system and for displaying data and diagnostic information. It is microprocessor-based and is operable to receive commands through a keyboaL^d and ~755i75 process the commands to corfigure the system and control its mode of operation. The contents of selected lines of the I/0 image and data table memory 12 can also be displayed and changed. The module 11 is mounted on the door of the processor housing and is 5 connected to the system I/0 scanner module 7 through the system backplane bus 1 and a ribbon cable.
MemorY Module As indicated above, one or more memory modules 2 may be connected to the system backplane bus 1 and any other module in 10 the programmable controller may read or write to these memory modules. In addition to storing one or more control programs, the memory module 2 stores considerable data which relates to the status and operation of each module in the programmable con-troller system. These data structures serve to coordinate the 15 operation of the various system modules.
Referring particularly to Figs. 1 and 9A-9D, the memory module 2 includes a system data section 620, an access control block section 621, a module status section 622, and a data table section 623. The system data section 620 occupies twenty-one 20 words of memory and is divided into fields that are dedicated to specific functions. The access control block section 621 is comprised of a set of data blocks, each associated with a par-ticular system module or section of the memory module 2. Each such block of data occupies five lines of memory and is divided 25 into fields which are dedicated to specific functions. The module status section 622 of the memory module 2 is comprised of blocks of data which each contain information concerning the status of specific system modules. And finally, the data tabie section 623 is comprised of sixteen sections, each of which is 30 dedicated to store a specific type of data.
Referring to Fig. 9A, the s~stem data section includes a number of fields which provide information concerning the status 117~;~i7~
of the programmable controller system. These fields are defined as follows:
Remote Access Request Counter. This counter indicates the number of remote devices requesting control of the programmable controller.
Outputs Reset Reauest Counter. This counter indicates the number of tas~s requesting that all output devices connected to the programmable controller be reset.
(Fl) Freeze Counter. F1 is a bit which indicates that the CPU module has been commanded to stop execution of the control program, and the counter indicates the number of tasks making this request.
(F2) SYnchronous Freeze Counter. F2 is a bit which indi-cates that the CPU module has been commanded to stop execution at lS the end of the next scan through the control program and the counter indicates the number of tasks making this request.
System Mode Data. This is a collection of status bits which indicate the mode of operation of the programmable controller, the memory protection mode and the programming mode.
I/O Prescan Counter. This is a four-bit counter used durir.g initialization to indicate the number of I/O scanner modules yet to complete their I/O prescans.
CPU Timer and Counter Field. This field is comprised of four parts: a CPU watchdog timer set-point; a CPU scan time high value; a CPU scan time present value; and a system counter 606.
The CPU watchdog timer set-point defines the timeout period which generates a fault condition if the CPU does not periodically reset the watchdog timer. The high value is the longest s~an time actually recorded and the present value is the ac_umulated time of the current scan. The scan time set-point is set by the CPU during its execution of the entire control program. This value is available to the user through the terminal ~. The system counter 606 has a number of uses. During the CPU pre-scan mode of operation this stores the number of pre-scans, and during the other CPU modes of operation this serves as a "heartbeat counter" which indicates to other modules in the system that the CPU module 3 is operating.
Real Time Clock. The remalnder of the system data section 620 is occupied by a real time clock which is periodically up-dated by the CPU module 3. ~his clock has a range from years to .0001 seconds.
Referring particularly to Figs. l and 9B, the access control block section 621 of the memory module 2 includes a five word block of data associated with each logical unit in the program-mable controller. Each access control block includes a number of fields which are dedicated to performing the following functions.
(X) Configure Command Bit. When this bit is set it indi-cates that this logical unit should be initialized and included in the system configuration prior to running the programmable controller.
(S) Status Bit. When set this bit indicates that the logical unit is ready to run.
(A) Memory Section Number. This six-bit number indicates the memory module section number to which the loqical unit re-lates. These are as follows:
0 = System data section 1 = Access control block section 2 = Module status section

3 = Data table section

4 = Control program section = Messages section 6 = System symbols 117~7S

7 = User symbols 63 = End of memory (B) Subsection Number. This four-bit number is a further definition of the logical unit. If the logical unit is a module,

5 this number deflnes the type of module as follows:
1 = Memory module 2 = CPU module 3 = I/O Scanner module 4 = Peripheral processor module = Communications network module On the other hand, if the logical unit is a data structure, this number indicates one of a plurality of such data structures, or in other words, the context of the data structure.
(C) Subsection Number. This four-bit number is yet a further definition of the logical unit. If the logical unit is a module, it indicates one out of a plurality of slmilar modules.
If the logical unit is a section of memory it defines a sub-section of that data structure. Referring particularly to Fig.
9D for example, this number identifies a subsection of the data 20 table portion of the memory as follows:
1 = Output image table 2 = Input image table 3 = Timer structures 4 ~ Counter structures = Binary integers

6 = Floating point numbers

7 = BCD integers

8 = Binary data

9 = ASCII characters lO = Gray code data 11 = Twelve-bit I/O data ~7~;75 (P) Write Protect bit~ When set, data is not to be written to the logical unit.
Access Counter. This indicates the number of processes which are currently accessing the logical unit.
Pointer. This is an address pointer to the start of the logical unit. If the logical unit is a data structure it points to its memory address and if the logical unit is a module, it points to the memory address for the module's status area.
The remaining two lines of the access control block 621 define the size of the logical unit when it is a data structure stored in the memory module 2. This information is needed to perform certain editing functions.
Referring particularly to Figs. 1 and 9C, each module in the system includes a corresponding block of data in the module status section 622 of the memory 2. Although much of the data in these module status blocks 622 is unique to each type of module, they do contain some common data structures. Such structures include a location word that identifies the module type, the module number, and its physical location on the system backplane.
ZO In addition, those modules which support processor-to-processor communications include a "module message block" data structure.
As will be described in more detail hereinafter, the message data block includes an interrupt address for that module, as well as a buffer containing the backplane address of each messaqe for the module. A pair of pointers indicate the next message address into and out of this buffer and a third word indicates the buffer's size.
When a module supports the front panel ll, its module status block 622 also includes a front panel data structure. In the preferred embodiment described herein the front panel is sup-ported by the I/O scanner module 7 and thus this data structure ~ ~J~ ~ S

appears in its module status block 622 as shown in Fig. l9C.
This data includes both physical and operating configuration data for the front panel serial port, as well as data regarding the control privileges allowed the front panel 11.
Referring still to Fig. 9C, the module status block 622 for the I/O scanner module 7 includes data structures corresponding to each of the four I/O channels. Each of these data structures includes a configuration word which indicates i~ the I/O channel is active, and if so, what purpose it is serving. Another word indicates the baud rate at which communications is occurring as well as further data which is peculiar to the particular purpose it is serving. In the preferred embodiment each I/O channel is connected to an I/O rack 16, and this further data is a single word which indicates the size, nature and address space of the I/O rack 16.
In summary, the module status blocks 622 store data which is available to all modules on the backplane bus 1 and which indi-cates the number and type of modules in the system and the basic functions they are performing. For example, by examining the module status blocks 622 the CPU module 3 can determine which module and channel on that module is supporting the terminal 8 and the front panel interface 11.
Referring particularly to Figs. 1 and 9D, the data table 623 ; in the memory module 2 is divided into fifteen sections, each of which stores a specific data type. Section 2, the input image table, stores input data which is received through either the system I/O interface module 6 or the system I/O scanner module 7.
This data is written into the memory module by the module 6 or 7 as it is received from the I/O racks 16. It is, therefore, an "image" of the state of the sensing devices which connect to the machine being controlled. Similarly, Section 1 of the data table 623 stores output data which is an image of the state of the operating devices on the machine being controlled.
The type, or form, of the data in the input and output image tables is the same as that of the particular input or output device to which it relates. For example, a position encoder which serves as an input device to the system may generate a digital number using a "grey" code, where as a bar code reader may generate input data as a series of "ASCII" characters. Such data is input automatically to the illpUt image table by the module 6 or 7 without alteration. It is then the responsibility of the user to employ "MOVE" instructions in the control program to transfer this data to the appropriate data type section of the data table 623. Althouth such a transfer of data using the MOVE
instruction does not perform a data conversion, when the MOVE
instruction is used to transfer data of one type to a data table section of another type, the appropriate data conversion is made.
Thus for example, a transfer of data using the MOVE instruction from the "binary data" section to the "BCD integer" section will make the appropriate data conversion. In addition, as will be explained in more detail below, when data is read from a par-ticular data type section of the data table 623 by the CPU module 3, it is automatically converted to a "native" data type which is consistent with the function being performed by the CPU module 3.
Conversely, when data is written back to the data table 623 by the CPU module 3, the data is automatically converted from the native data type back to the indicated form.
CPU Module Referring particularly to Figs. 1 and 2, the CPU module 3 is structured around a CPU bus 20 which includes a 16-lead CPU
address bus 21 and a 16-lead bi-directional CPU data b~s ~.

5~i75 These are coupled to the system backplane bus l by a processor interface circuit 23 and they connect to a central processor 24, a read-only memory 25 and the I/O image and data table memory 12.
The read-only memory 25 is an 8K x 16-bit high-speed EPROM which 5 stores power-up and house keeping programs, masks, and other constants. This data is read onto the CPU data bus 22 either in response to microinstructions executed by the central processor 24 or in response to a read operation initiated by one of the modules connected to the system backplane bus l. In the latter

10 case, the data is coupled through the processor interface circuit 23 and backplane bus 1 to the requesting module.
The I/O image and data table memory 12 is a high-speed random access memory organized as 4K x 16-bit words. This memory 12 stores an image of the most often accessed portion of the I/O
15 image table. The central processor 24 accesses the memory 12 to determine the status of system inputs, and the central processor 24 modifies the contents of the memory 12 to effect changes in system outputs. The remainder of the I/O image table is stored in the data table portion 623 of the memory module 2, and the 20 central processor 24 accesses this data as well. The CPU module 3 couples data which indicates "changes" made in the I/O image table through its processor interface circuit 23 to the cor-responding I/O image tables in the I/O bus interface module 6 and I/O scanner module 7. The memory 12 also stores data associated 25 with the execution of certain macroinstructions, and in general, it provides storage for data which is to be accessed at high speed.
Referring particularly to Fig. 2, the central processor 24 is a 15-}~it, microprogrammed processor which fetches macro-30 instructions (user control program instructions) from the memorymodule 2, and decodes each into one or more rnicroinstructions ;75 which perform the r2quired operations. The processing of a macroinstructlon may also require further access to the memory module 2 or the RAM memory 12 for operands or other required data.
The central processor 24 is structured about an arithmetic and logic unit, ALU 26, which is comprised of four cascaded 4-bit bipolar microprocessor slices (AM2903) manufactured by Advanced Micro Devices, Inc. The ALU 26 includes sixteen internal regis-ters (Reg 0-15) and it receives 16-bit data input words at a DA
port 27 or a DB port 28. The ALU 26 performs a number of arithmetic and logic functions in response to signals on a control bus 29 and 16-bit data output words are generated at a Y
port 30. Eor a detailed description of the ALU 26 reference is made to "The AM2900 Family Data ~ook" published in 1979 by Advanced Micro Devices, Inc.
The operation of not only the ALU 26, but also the remaining elements of the central processor 24 is controlled by 56-bit microinstructions which are sequentially read from a microprogram store 31 to a microinstruction register 32. Referring par-ticularly to Figs. 2, 5A and 5B, the 56-bit microinstructions which control the operation of the central processor 24 are divided into micro fields. Each micro field is a code of one or more bits in length which is decoded to provide control signals to specific elements of the central processor 24. For example, the micro field formed by bits 0-3 of each microinstruction operate a microsequencer 33 to control the order in which microinstructions are read from the microproyram store 31. The micro field formeà by bits 1~-15 on the other hand, control the arithmetic and log,c functions performed by the ALU 26 and the micro field formed by bits 28-31 control the various latches and gates which attach to the ALU Y-port 30 through a 16-bit Y-bus 7~i~75 34. Some of the micr~instruction bit lines are attached directly to the elements which they controi while others are combined and decoded to provide control signals for various system elements.
This decoding circuitry is shown collectively in Fig. 2 as reference number 35 and the resulting control lines form the control bus 29. The actual control lines have not been shown in Fig. 2, but instead, Appendix A lists the function performed by each decoded micro field using the mnemonics in Figs SA and SB.
Referring particularly to Fig. 2, the macroinstructions from the user control program are read into the central processor 24 through the processor interface circuit 23 and stored in a 16-bit macroinstruction register 39. The macroinstruction register 39 retains the macroinstruction word for reference during the execu-tion of the resulting microroutine. A lO-bit operation code in the macroinstruction is applied through a macro-bus 40 to the address inputs of a map/vector ROM 41, and a 4-bit bit-pointer code is applied to the address inputs of a ~it pointer rom 43.
The operation code is converted by the ROM 41 to a twelve-bit microaddress which is applied to a microbranch address bus 44.
This decoded operation code is employed to address a microroutine which is then executed to perform the functions indicated by the operation code. The four least significant bits of the macro-instruction may a1so directly drive the four least significant bit leads in the 12-bit microbranch address bus 44 through a data selector 45. The data selector 45 is enabled when special 16-way microbranch instructions are executed that require four bits from the macroinstruction.
The microsequencer 33 is an address sequencer for control~
ling the sequence of execution of microinstructions stored in the 3~ microprogram store 31. During the execution of each micro-instruction, the microsequencer 33 provides a 12-bit address on a ~7~i75 bus ~l9 to the microproy-am store 31. This address selects one of 4096 microinstructions to be executed next. The address gen-erated by the microsequencer 33 may originate from one of four sources within the microsequencer 33: (1) a microprogram address register, which usually contains an address one greater than the previous address; (2) an external direct input from the micro-branch address bus 44; (3) a register/counter retaining data loaded during a previous microinstruction; or (4) a five-deep last-in, first-out stack register which provides return address linkage when executing microsubroutines or loops. The micro-se~uencer 33 is responsive to microinstruction bits 0-3 to perform one of sixteen operations, nine of which are conditioned by a signal on a control line 50. That is, an operation such as a jump is performed only if the control line 50 is at a logic low voltage. The microsequencer 33 is available in integrated circuit form as the AM2910, and for a more complete description of its structure and operation, reference is made to "The AM2900 Family Data Book With Related Support Circuits" published in 1979 by Advanced Micro Devices, Inc.
The control line 50 is driven by a status multiplexer 51 which is controlled by bits 40-43 in each microinstruction. The status multiplexer 51 receives a status signal from an interrupt interface circuit 52 through a control line S3 and it receives status signals from a 4-bit status register 54. The inputs of the status register 54 are driven by the "carry", "overflow", "zero" and "sign" status outputs of the ALU 26. The operation of the microsequencer 33 can thus be conditioned by the status of the ALU 26 or by the existence of an interrupt request from the interrupt interface circuit 52.
Referring still to Fig. 2, a microprogram address may be supplied to the microsequencer 33 through the bus 44 from a 7~

number of so~lrces. Fcr example, when a macroinstruction is fetched its operatlon code is applied to the map/vector ROM 41, and it is converted, or mapped, to a 12-bit microprogram address which is generated on the bus 44. In this manner, each macro-S instruction is mapped to its corresponding microroutine. Also,when a jump microinstruction is executed, bits 44-45 of the microinstruction are coupled directly to the bus 44 from the microinstruction register 32. This "target address" identifies the point in the microprogram at which processing is to continue.
10 In addition, a 12-bit microaddress may be coupled from the Y port 30 of the ALU 26 through a set of gates 56. This allows, for example, the target address of a microjump to be calculated by the ALU 26. And finally, microaddress data may be coupled to the microsequencer 33 from a data selector 45 and an interrupt 15 interface 52.
Referring to Fig. 2, the central processor 24 includes other elements which enable it to perform a wide variety of functions.
Gates 46 couple data from the bus 40 to the ALU 26, and when enabled for example, they allow the 9-bit operand address which 2û accompanies a bit pointer code to be coupled through the ALU 26 to an address latch 47 and then to the CPU address bus 21. Gates 48 on the other hand, connect the CPU data bus 22 to the OA port 27 on the ALU 26. This enables a 16-bit data word from either the processor interface circuit 23, the I/O image and data table 25 memory 12 or the read-only memory 25 to be applied through the gates 48 directly to the ALU 26. In addition, bits 40-55 of the microinstruction register 32 are coupled to a set of sixteen gates 57 and the outputs of gates 57 are connected to the DB port 2~ on the ALU 26. A sixteen bit data word can thus be applied to 30 the ALU 26 "immediately" by a microinstruction. Such a data word might be, for example, a mask which is logically combined with a data word a~plied to the ALU DA port 27. Also, the output of the ALU 26 may be coupled through the Y-bus 34 to a 16-bit data latch 58, the address latch 47 or the processor interface circuit 23.
The data latch 58 connects to the CPU data bus 22 and the output of the ALU 26 can thus be written into tne I/O image and data table memory 12. And finally, the ~LU Y-bus 34 connects to the input of a time base and watchdog timer circuit 59. As will now be described in more detail, the output of this circuit 59 also connects to the ALU DA input port 27.
Referring particularly to Figs. 2 and 4, the time base and watchdog timer circuit provides the system clock signals and the real time clock signals employed in timer macroinstructions. It includes a 20 megahertz single phase clock 60 which drives a clock line 61 through a driver 62. The 20 megahertz clock 60 lS also drives a 4-bit binary counter 63 which generates a system clock signal on a line 64. The system clock provi&es a time base of 200, 250 or 300 nanoseconds depending on the type of instruc-tion being executed. The system cloc~ can be inhibited, by a NAND gate 65 which is responsive to a HOLD signal on a control line 66.
The 20 megahertz clock also drives a divider circuit 67 through an inverter 68 and a D-type flip-flop 69. The divider 67 is comprised of a series of dividers and counters which reduce the ciock rate to values that provide the desired time bases.
More specifically, a time base of one millisecond is generated on a line 70, a time base of .01 seconds is generated on a line 71 and a time base of .1 seconds is generated on a line 72. ~n addition, an 8-bit latch 73 connects to the divider 67 to store a 4-bit binary count of the .01 second time intervals, a 2-bit binary count of the .1 second time intervals and a 2-bit count of .5 second intervals. The eight Q outputs on the latch 73 connect s to the ALU DA port 2, through bus 74, and when a logic low con-trol signal is received on a l-ne 75, the contents of the latch 73 are read into the ALU 26.
The line 70 increments an 8-bit scan counter 76 which serves as a means for measuring the time required to execute the user's control program. The eight inputs to the scan counter 76 are connected to the eight least significant leads in the Y-bus 34 and it is preset through a control line 77 to the one's compli-ment of the maximum allowable scan time prior to each pass through the user's control program. As the user's control program is executed, the counter is incremented in ten milli-second time increments until it overflows, or is again preset at the beginning of the next scan. A NAND gate 78 connects to detect an overflow and it generates a logic low voltage on a control line 79 when this event occurs. As will be explained in more detail below, the control line 79 connects to the interrupt interface circuit 52 to initiate an interrupt when the scan counter "times out". In addition, a set of eight tri-state gates 80 connect to the outputs of the scan counter 76, and when a logic low voltage is applied to control line 81, the contents of the counter 76 is read onto the bus 74 and into the ALU 26. In this manner, the time required to execute the control program, or portions of it, can be measured.
Referring particularly to Figs. 2 and 6, the interrupt interface circuit 52 receives interrupt requests from seven sources, prioritizes them, and generates a code to an interrupt PROM which supplies the starting address on the microbranch address bus 44 of the highest priority service routine~ Six of the interrupt requests are received at the clock terminals oL
respective D-type flip-flops 83-88 and the seventh is applied directly to one input of an 8-bit latch 89. Three of the 1~7~5i75 interrupt requests eminate from the time base and watchdog timer circuit described above to interrupt processing when the allow-able scan time has been exceeded or when the .01 second real-ti.~e clocX has "ticked" or when the .1 second real-time clock has ticked. A fourth interrupt request eminates from a line 90 in the backplane bus when a module attached thereto requests an interrupt, and a fifth interrupt is requested by line 91 when a.c. power failure is detected. The remaining two interrupts are fault related. The first appears on line 92 when an error is detected during a read or write operation to the system backplane bus 1 and the other appears on line 93 when a fault such as a memory parity error occurs.
Any interrupt requests remain in the respective flip-flops 83-88 until serviced. The Q outputs of flip-flops 83-88 are connected to inputs on the latch 89 and the interrupt requests are latched in synchronizm with the 5 MHZ system clock. The eight latch outputs are coupled to a priority encoder 94 through respective NAND gates 95-101.
The NAND gates 95-101 enable interrupt requests to be masked. A second input on each connects to a respective output of an eight-bit addressable latch 102 which has its three latch select inputs and its data input connected to the Y-bus 34. When a control line 103 is driven low, a selected one of the NAND
gates 95-101 may be either enabled or disabled (i.e. mask the interrupt) by data which is output from the ALU 26 to the addressable latch 102.
The priority encoder 94 generates a three-bit binary code at its outputs 104 which identifies the highest priority interrupt applied to its eight inputs. A "~0" output on the priority encoder 94 connects to the control line 53 and it is driven high if any interrupts are requested. The outputs 104 connect to the address inputs of the interrupt PROM 105, and the 3-bit code thereon is mapped to the starting address of the corresponding interrupt service microroutine. When the interrupt PROM 105 is enabled by control line 106, this address is applied to the bus 44 and loaded into the microsequencer 33.
After an interrupt has been serviced the request is reset.
Referring still to Fig. 6, this is accomplished by a 3-line-to-8-line decoder 107 which has its three inputs connected to leads 0-2 in the Y-bus 34. Six of its outputs are connected to reset terminals on respective flip-flops 83-88, and when enabled by a control line 108, the flip-flop indicated by the 3-bit code on the Y-bus 34 is reset. The interrupt indicated on line 93 requires a manual reset following correction of the indicated fault.
I~ should be apparent that the interrupt interface circuit 52 may be expanded to enable additional interrupt input events and that the nature of the interrupt events can be easily changed by altering the contents of the interrupt PROM 105.
There are certain functions performed by a programmable controller which to a great extent determine its capacity in terms of the number of I/O points it can support. The preferred embodiment described herein is intended to service up to 4096 input points and 4096 output points without degradation of the scan time (i.e. the time needed for a single execution of the user control program). This is accomplished in part by main-taining the I/O image and data table in the memory 12, which is not only constructed using high speed memory devices, but which is also physically located on the same circuit board as the central processor 24. Most operations performed by the central processor ~4 involve this local high speed memory, because most instructions in the typical user control program require the ~.L~5S~5 examination of a single bit in the I/O image table or the setting of a single bit in the I~O image table. The separation of the CPU bus 20 from the system backplane bus l and the use of local high speed memory therefore substantially enhances the speed of the CPU module 3.
As indicated above, it is the function of the system I/O bus interface module 6 and the I/O scanner module 7 to periodically update the state of the I/O image table in the memory 12 and it is a function of the central processor 24 to fetch control in-structions (i.e. macroinstructions) from the memory module 2.
These functions require bi-directional communications between the central processor 24 and the system backplane bus 1. Also, because a number of asynchronously operating modules are con-nected to the system backplane bus l, an arbitration means must be provided to allocate the backplane bus 1 to the requesting system module or the central processor 24 in accordance with a preselected priority scheme.
These functions are performed by the processor interface circuit 23. Referring particularly to Figs. 1, 2 and 3A, the sixteen leads in the CPU data bus 22 are coupled to the sixteen leads in the system backplane bus ld by a 16-bit latch 109. Data is clocked into the latc~ 109 from the bus 22 when a control line 110 goes high and this data is applied to the backplane data bus ld when a control line lll becomes active. On the other hand, a set of sixteen tri-state gates 112 and a latch 113 couple the backplane data bus ld to the CPU data bus 22. When enabled by control lines 114 and llS data from the backplane bus 1 may be coupled through the gates 112 and the latch 113 and written to an addressed destination in the central processor module 24. It is in this manner, for example, that the system I/O bus interface module 6 updates the IjO image and data table memory 12 with changes occurring at input points in the I/O racks 16.

5~`~5 In addition to coupling the respective data buses ld and 22, the gates 112 also input control program macroinstructions which are fetched from the memory module 2. These macroinstructions are applied to the inputs of a first macro latch 116 and to the inputs of a second macro latch 117. As fetched macroinstructions are received, they are alternately loaded into the respective latches 116 and 117. This enables macroinstructions to be "pre-fetched" so that the central processor module 24 can operate at maximum speed without waiting for the next macroinstruction~
Control of the latches 116 and 117 is accomplished by a flip-flop 118 and a pair of NAND gates 119. The flip-flop 118 serves to alternately clocX the latches 116 and 117 and to time the clock pulse such that the macroinstruction is latched properly when received from the memory module 2. As a result, when a macro-instruction is fetched, a control line 120 becomes active and one of the two NAND gates 119 is momentarily gated to clock one of the latches 116 or 117.
The output of the latches 116 and 117 connect to the leads in a macroinstruction bus 121 which connects to the inputs of the macroinstruction register 39. A flip-flop 122 connects to the enable terminals on the respective latches 116 and 117, and the contents of the latches are alternately output to the macro-instruction register 39 in response to signals on control line 123. A set of flip-flops and gates indicated generally at 124 keep track of macroinstructions loaded into and read out of the latches 116 and 117, and if a request is made for another macro-instruction and none is available, an active signal is generated on the control line 66 to disable the central processor clock (see Fig. 4). The central processor is thus held in an idle state until another macroinstruction is received from the memory module 2. Control lines 126 and 127, which also emanate from this circuit, indicate when either of the latches 116 or 117 is ~1~5~ S
empty, and as will be described below, these signals initiate a prefetch of another macroinstruction when either of the macro latches 116 or 117 is empty.
As long as the control program macroinstructions are exe-5 cuted in sequence, the subsequent macroinstructions are pre-fetched to the macro latches 116 and 117 and are available when needed by the central processor 24. However, When the control program deviates from a straight sequential execution of macro-instructions, as occurs during a jump or branch, the prefetched macroinstructions in the latches 116 and 117 are of no use. When this occurs, a control line 125 is enabled and the flip-flops 124 are reset to indicate that no macroinstructions are available for execution.
Referring particularly to Figs. 2 and 3B, the ALU Y-bus 34 is also coupled to the system backplane bus 1 through the proces-sor interface circuit 23. It connects to the system data bus ld through a 16-bit data latch 130 and it connects to the system address bus la through a pair of address latches 131 and 132.
The data latch 130 is loaded with data which is output from the ALU 26 when a control line 133 is active (i.e. micro-bits 28-31 = BACKD) and this data is written onto the backplane data bus ld when a control line 134 is active. Similarly, addre data is output to the respective latches 131 and 132 when control lines 135 and 136 are active ~i.e. micro-bits 28-31 = BACKL or BACKH) and this 26-bit address is applied to the backplane address bus la when a control line 137 is active. Data and addresses can thus be generated directly by the ALU 26 for application to the backplane bus 1, and hence to other modules in the s-ystem.
Control program macroinstructions stored in the memory module 2 are addressed by the CPU module 3 by means of data stored in a 16-bit latch 138 and a lO-bit latch 139. The inputs 1~5575 of the 10-bit latch 139 are connected directly to leads in the Y-bus 34, however, the inputs to the 16-bit latch 138 are driven by a 16-bit "macro" counter 140. The macro counter 140 may be preset to an address generated by the ALU 26 on the Y-bus 34 when a control line 141 is active (i.e. micro-bits 28-31 = FETCH) and the counter 140 is incremented each time a macroinstruction is fetched. This is accomplished by a control line 142 which emanates from the clock terminal of flip-flop 118 (see Fig. 3A).
The contents of the macro counter 140 are loaded into the latch lo 138 when control line 143 becomes active, and the 10-bit latch 139 is loaded with high order address data from the Y-bus 34 when the control line 144 becomes active. The resulting 26-bit address is applied to the backplane address bus la when the central processor module 24 obtains access to the backplane bus 1 and a control line 145 becomes active.
Referring to Figs. 2 and 3C, a module connected to the system backplane bus 1 accesses the CPU module 3 by asserting an address within a preselected range on the address bus la and asserting the proper signals on the system backplane bus control lines. Ten of the most significant digit leads in the system address bus la couple to the "A" inputs of a comparator circuit 150, and when the CPU module 3 is addressed by another module, the comparator 150 generates a logic high voltage at an output 151. A set of module ID switches, or jumpers 152, connect to the "B" inputs of the comparator and these serve as a means for preselecting the CPU access address range.
The module requesting access to the CPU module 3 also asserts a logic low voltage on a backplane control line (XCMD) 153 to indicate that valid data is present on the backplane bus 1. This signal is inverted and applied to the clock terminals on two D-type flip-flops 154 and 155 and to the K terminal on a J-K
flip-flop 156. The output of the comparator 150 is thus clocked _~9_ li7~S75 into the flip-flop 154 and applied to one input of an AND gate i56. A second lnput 157 on AND gate 156 connects to receive bit 4 from the microinstruction register 3~, and if access to the CPU
module 3 is to be blocked, it is set low. Otherwise, the output of AND gate 156 is clocked into a second D-type flip-flop 159.
The Q and Q outputs on the second D-type flip-flop 159 enable a number of elements in the CPU module 3. The Q output connects to an enable terminal 150 on a set of sixteen address gates 161 and a sixteen bit address is thus applied to the CPU
address bus 21 when access to the CPU module 3 is obtained. The Q output of flip-flop 159 connects directly to control line 110 to disable the address latch 47 (Fig. 2) and to enable the inputs of the latch 109 (Fig. 3A). In addition, this Q output connects through an OR gate 162 to a control line 163 which disables the data latch 58 (Fig. 2) when external access is granted. A second input on the OR gate 162 is driven by a control line 164 which becomes active during a central processor write operation (i.e.
micro-bits 35-37). The Q output on flip-flop 159 also connects to one input of a NA~D gate 165. The second input on this NAND
2G gate 165 is driven by a control line 166, and when data is to be read by the CPU module 3, the output of gate 165 is driven low.
The output of gate 165 drives a pair of AND gates 167 and 168.
The AND gate 167 in turn drives the control line llS which con-trols latch 113 (Fig. 3A) and the AND gate 168 drives a CPU WE
control line 169. When a module on the system backplane bus 1 writes to the CPU module 3, therefore, the control lines 115 and 169 are driven low.
The J-~ flip-flop 156 is set shortly after the flip-flop 159 by the system clock applied to its clock terminal. The Q output on flip-flop 156 connects to an inverter gate 170 that drives a backplane acknowledge ~XACK) control llne 171. The signal thus 1~l7~i'75 generated on the XACK cor.trol line 171 indicates to the request-ing module that the CPU module 3 has received its request and that valid data is on the system bus 1. The flip-flop 156 also drives a NAND gate 172, and if a read operation is indicated by S the backplane read/write line 166, the output of this gate 172 is driven low to enable the outputs of latch lO9 (Fig. 3A) through control line 111. The flip-flops 154 and 156 are reset by the backplane control line XCMD 153 and the signal is removed from the XACK control line 171 by the flip-flop 156 to indicate that the data transfer is complete.
Referring to Figs. 2 and 3C, in addition to reading from or writing to the CPU module 3, an external module may also inter-rupt the central processor 24 or force it into a "hold" state.
An interrupt request is accomplished by writing to a specific lS address which causes an interrupt request to be generated on a line 9O by a NAND gate 173. One input to this gate 173 is ena~led low by the NAND gate 165 when a backplane write operation is indicated, and its other input is enabled low when the pre-selected interrupt address is present on the CPU address bus 21.
A decoder circuit 174 detects not only this interrupt address, but it also decodes other addresses on the bus 21 to generate appropriate chip enable signals to the I/O image and data table memory 12 and the read only memory 25.
An external module may also place the central processor 24 in "hold" by asserting a logic low voltage on a backplane control line (CPU HOLD~ 175. This signal is coupled through an inverter gate 176 and AND gate 177 to the D input of the flip-flop 155.
The Q output of flip-flop lS5 connects to the D input of another D-type flip-flop 178 and the output on this flip-flop 178 connects to the hold control line 66 to disable the system cloc~
(Eig. 4). The central processor 24 remains in the hold condition until another backplane command is generated to reset the flip-flops 155 and 178.
Referring particularly to Figs. 2, 3D and 15, the central processor 24 contains circuitry for determining which module in the programmable controller may have access to the backplane bus 1. An arbitration request control line 182 connects to each module on the backplane bus 1 and when a module wants access, it asserts an arbitration request logic signal to the arbitration circuit on the central processor 24. This signal sets a flip-flop 183, which in turn applies a logic signal to a shiftregister 184. The shift register 184 generates a 200 nanosecond arbitration pulse on a backplane control line 186, and as will be described in more detail hereinafter, the requesting module having the highest priority will respond to this pulse by asserting a signal on a WIN control line 180. The successful module will then assert a "bus busy" signal on a backplane control line 181 and initiate a data transfer.
The central processor module 24 may gain access to the backplane bus 1 when no other module in the programmable controller needs it. Referring to Fig. 3D, this condition is sensed by an OR gate 1~7 which sets a flip-flop 188 when the backplane bus 1 is not requested by another module. The flip-flop 188 drives a pair of NOR gates 189 and when the central processor module 24 wants access, as indicated by the logic state of a WANT control line 190, a logic high enabling signal is generated on an IGOT control line 191. The IGOT control line l9i drives the BUS BUSY control line 181 and it enables a series of AND gates 192 which couple the processor module 24 to the bàcX-plane HOLD control line 175, the control line 137 (see Fig. 3B), the bac~plane read/write control line 166 and the control line 145 (see Fig. 3B).

;75 The W.~NT control line 1~0 is enabled whenever the central processor module 24 requires the backplane bus 1 to perform a read operation, a write operation or a macroinstruction EETCH. A
BACK READ control line 193 is enabled when a BACKR microcode is executed and a BACK WRITE control line 194 is enabled when a BACKW microcode is executed. These signals along with the macroinstruction buffer empty signals on lines 126 and 127 are applied to an OR gate 195 and to the respective inputs of a quad D-type flip-flop 196. The output of the OR gate 195 drives a D-type flip-flop 197 which is set by a NAND gate 198 when access is desired and the flip-flop 197 generates a logic low signal on WANT control line 190. This logic low voltage releases a shift register 185 from reset and a logic high voltage is generated by the flip-flop 197 to an AND gate 199 to clock the quad flip-flop 196. The contents of the quad flip-flop 196 is gated to the respective control lines 175, 137, 166 and 145 by the AND gates 192, and a short time thereafter, the XCMD backplane control line 153 is activated by the output of the shift register 185 to indicate that valid data is on the system backplane bus 1. When the module with which the central processor module 24 is communi-cating acknowledges that the data transfer has occurred, the backplane control line XACK 171 rises to a logic high voltage to clock the flip-flop 197 and to thereby either initiate another transfer or reset it.
Referring particularly to Fig. 15, the arbitration process is performed concurrently with the transfer of data between modules. That is, prior to the completion of a read or write cycle on the backplane bus 1, the arbitration process has already occurred and the highest priority module desirin~ access to the backplane bus 1 has been found and is ready to perform a read or write operation when the bus becomes available. Bus ava lability is indicated by a logic high on the bus busy control line 181 and ~75~75 shortly thereafter the new "master" module of the backplane bus initiates a read or write cycle. The master module drives the XCMD control line 153 low to indicate that a valid address is on the backplane bus l and the addressed "slave" module responds by driving the XACK control line 171 low. The XCMD control line 153 is released by the master module shortly thereafter and the slave module responds by releasing the XACK control line 171 to com-plete the read or write cycle.
Any module, except the CPU module 3, can request arbitration by driving the control line 182 low. As described previously, this causes an arbitration pulse to be sent to all modules through the control line 186, and the highest priority module will drive the WIN control line 180 low to terminate arbitration.
That module will then take control of the bac~plane bus 1 when the bus busy control line 181 goes high.
Referring particularly to Figs. 1, 2, 8 and 9, when the CPU
module 3 is powered up it operates in one of five possible modes.
In mode 1 the CPU module 3 is not processing, but is waiting for other modules in the system to initialize. In mode 2, it is waiting for the I/0 scanner module 7 to perform a "prescan" which initializes the I/0 image and data table memory 12 and the data table in the memory module 2. In mode 3 the CPU module 3 per-forms a "program prescan" in which the control program is exe-cuted, but all output devices are disabled. Mode 4 is the "run"
mode in which the control program is executed to operate the devices connected to the programmable controller, and mode 5 is the program load mode in which the control program is entered and edited from the terminal 8. The current CPU mode is stored in the CPU ram 12 a~d in the system status portion of the memory module 2.
Referring particularly to Figs. 8 and 9, regardless of the mode of operation, the CPU module 3 periodically performs a ~:~7~i~ii75 number of housekeeping cnores. As indicated by process block 600, a set of instructions are executed to increment the system counter and the real time clock which are both stored in the system data portion 620 of the memory module 2. The system counter indicates to other modules in the system that the CPU
module 3 is functioning and the real time clock provides day and time information. As indicated by process block 601 the CPU
module 3 then refreshes certain data in its memory 12. More specifically, it reads data from the access control block portion 621 of the memory module 2 which indicates the memory location of various portions of the control program and the data table stored in the memory module 2. These "pointers" are maintained in the CPU memory 12 to reduce the time required to access data in the memory module 2 during execution of the control program. If this data is in error, as indicated by decision block 602, the CPU
module is shut down and all output devices are disabled.
Normally, however, the CPU module 3 next executes commands it has received from the terminal 8 as indicated by process block 603.
As will be explained in more detail hereinafter, the CPU module 3 includes a message handler routine which communicates with other backplane modules, and which couples command messages from the module that supports the terminal 8. Such commands may be, for example, editing commands which call for the deletion or addition of instructions in the control program.
Referring still to Figs. 8 and 9, after these housekeeping functions have been performed, the CPU module 3 determines which mode it is operating in and performs the functions required. Im-mediately following power-up the CPU module is in mode 1 as determined by decision bl~ck 604, and the only function performed is to determine if the other modules in the system have been initialized and are ready to run. This is determined by instruc-tions indicated by decision block 605 which examine the system ts status counter 606 storeà in the system data portion of the memory module 2. .~s will be explained in more detail herein-after, the system I/O scanner module 7 is responsible for setting the system status counter 606 to the number of modules present during power-up. As each module initializes itself, it decre-ments the system counter. Until this counter is decremented to zero, the CPU module 3 remains in the mode 1 loop comprised of blocks 600-605.
When all system modules have initialized the CPU module 3 may switch to mode 2. Before doing so, however, a chec~ is made to determine if the sys~em has beer. set to the "program load mode." This is indicated at decision block 607 and is accom-plished by examining the system mode field 608 in the system status portion 620 of the memory module 2. As will be explained in more detail hereinafter, it is another one of the functions of the system I/O scanner module 7 to monitor the front panel switches through the front panel interface module 11 and to maintain the system mode field 608.
In mode 2 the CPU module 3 waits for the I/O scanner module 7 to perform an I/O prescan in which the data tables in both memory module 2 and CPU ram 12 are initialized to the current state of all input devices connected to the programmable con-troller. Instructions indicated by decision bloc~ 609 are executed to examine an IjO prescan counter 610 in the system status portion of memory module 2. Each I/O scanner module 7 and system I/O bus interface module 6 in the system decrements this I/O prescan counter 610 when it has completed its prescan, and when the counter 610 reaches zero, the CPU module 3 switches to mode 3.
In mode 3 the CPU module 3 executes a "prescan" of the control prvgram to build a table of target addresses for jump instructions and subroutine calls as described in U.S. Patent No.
4,115,353. As indicated by process block 611, a master control relay is first set by the CPU module 3 to insure that all logic decisions made during the control program prescan are false and that no output devices are energized. Also, during the prescan no branches jumps or subroutine calls are executed to insure that each and every instruction in the control program is fetched and executed. As indicated by process block 612, each control pro-gram instruction is fetched from the memory module 2, mapped to the proper microprogram in the CPU module 3 and executed. The last microinstruction in each microprogram includes a FETCH code which directs the CPU module 3 to read the next control program instruction from the memory module 2.
This sequence continues until the "END" instruction is fetched. The END instruction functions to reset the control program counter to the start of the control program and to read the scan counter 76 (Fig. 4). The scan counter 76 is reset to zero and the scan time is saved in the system data section (Fig.
9) as indicated by process block 613 in Fig. 8. The scan time is a measure of the time required to execute the control program and is particularly useful in time-critical applications where the effects of changes to the control program during program develop-ment cannot be easily predicted.
Referring still to Fig. 8, if the control program prescan ~s complete as determined at decision block 614, the CPU module 3 is ready to run. First, however, a check is made at decision block 615 to determine if the program load mode has been requested, but if not, the module is set to mode 4. Regardless of the mode, after the control program has been executed a check is made of the system data section to determine if any major fault condi-tions have occurred as indicated at process block 616. The ~L~75~i75 system loops back to commence another scan if no problems exist.
Otherwise, the system shuts down.
Referring particularly to Fig. 1, the control program in-structions, or "macroinstructions," are loaded into the memory module 2 using the terminal 8. The terminal 8 operates in com-bination with the peripheral processor module 5 to not only load macroinstructions into the memory module 2, but to also edit the resulting control program and to monitor the system operation as the control program is being executed by the CPU module 3. As will become more evident from the description to follow, a number of macroinstructions infer or expressly define operands, which are stored in the I/O image and data table memory 12. This memory 12 is on the CPU module 3 and is constructed of very high speed devices which enable the macroinstructions to be executed more efficiently. Typically, each macroinstruction is prefetched by the CPU module 3 from the memory module 2 and it is held until the previous macroinstruction has been executed. When that is completed, the macroinstruction operation code is mapped to a stored microprogram which carries out the indicated functions.
Typically, the function is carried out with one or more operands located in the I/O image and data table memory 12.
The macroinstruction set includes many instructions which are common to programmable controllers such as bit manipulating instructions and timers and counters. Others are less common and some are unique either in the function they perform or the manner in which they perform the function. The macroinstruction set can be grouped into a number of subsets as set forth in Table A. The microprograms for a representative sampling of these macroinstruc-tions is set forth in Appendix ~.
Referring particularly to Figs. lOA-lOE, each macroinstruc-tion includes an operation code and an operand or operand 75;~75 address. The "rung control" and "program control" macroinstruc-tions are one 16-bit word in length and each includes an 8-bit operation code. The rung control instructions also include an 8-bit offset number which may be added to the macroinstruction counter to branch around control program instructions which are not to be executed. The program control instructions include an 8-bit label number which identifies an entry in the label table which is stored in the CPU ram 12 and which is created during the control program prescan.
The "test/control bit" macroinstructions are formed by a 16-bit word containing the 8-bit operation code and a 4-bit pointer code followed by one or more operand address words.
"Timer/counter" macroinstructions are similar except they include a 7-bit timer/counter number and a single bit (L) which indicates whether or not the macroinstruction includes additional words for addressing beyond the range of the 7-bit timer/counter number.
The "arithmetic/logic" instructions are more complex. In addition to the first word which contains the 8-bit operation code, they include one or more words which indicate the address of a first source of data, a second source of data and a destina-tion for the output of the arithmetic or logical operation. The first word of the arithmetic and logic instructions also includes a bit (I) which indicates if any of the data to be operated upon is floating point and a bit (F) which indicates if any of the data to be operated upon is more than one word (i.e., a file).
The remaining 5 bits in the first word indicate the total number of words in the macroinstruction. If a data file is operated upon as ir,dicated by the F bit, the first word in an arithmetic or logic macroinstruction is followed by one or more ile control words which indicate how the file is to be processed.
The address structure reîerred to above in connection with Figs. lOc-lOe is shown in more detail in Fig. 11~ It is com-~557S

prised of or.e or two words as determined by a single bit (L) inthe first word. Another bit (F) in the first word ndicate~s if a file is being addressed and the first four bits of the word indicate which of the sixteen sections of the data table is being addressed. The remaining ten bits of the first word identify a location in the indicated data table section or they form the most significant bits of a much larger address when a second word is present in the structure. The structure of the data table portion of the memory module 2 is shown in Fig. 14 and it should be apparent from the above description that the size of any of the sixteen sections of this data table can range to a very large capacity.
When arithmetic or logic macroinstructions operate on a file, they require a file control word shown in Fig. lOe. The structure of such file control words is shown in more detail in Fig. 12. The structure is comprised of one or two words as determined by the first two bits of the first word and the same two bits determine in which of two modes, complete or distributed complete, the file is to be operated upon. In the complete mode ~0 the file control word is a transfer number which indicates the number of words to be operated upon in the indicated file or files. Each time the macroinstruction is executed, the arithmetic or logic operation is sequentially performed on the number of words in the file indicated by this number. In con-trast, the distributed complete mode of operation requires a ratenumber in addition to the transfer number, and each time the macroinstruction is executed, only the number of words indicated by the rate number are operated upon. This continues until the total numbsr of words indicated by the transfer number are operated upon. This distributed complete mode of operation on a data file enables the operations to be distributed over a number ;'7S

of scans so that the control program scan time is not excessive when an operation on a large data file is made.
Referring particularly to Fig. 13, for each timer and counter required by the control program there exists a three-word data structure in the timer or counter sections of the data table stored in memory module 2. This structure includes a control word which indicates the status of the timer or counter, a preset value word, and an accumulated value word. The accumulated value word stores the number of counts or time increments which have taken place and the preset value word stores the total with which the accumulated value is compared.

TABLE A
MACROINSTRUCTIOM SET

1. Rung Control Instructions STRT Transparent "start of rung" instruction which includes a program counter offset to the first conditional or branch output instruction in the rung. It sets the condition of the rung to the state of the master control relay (MCR) and it provides the information needed to skip instruc-tions that need not be executed.

STMC Same as STRT, but it sets the rung condition true irrespective of the MCR or ZCL state.

BST Defines the start of a branch in a rung and in-cludes a program counter offset to the next NXB
instruction to allow skipping of instructions in a false branch.

NXB Defines the start of another branch and includes a program counter offset to the next NXB or BND
instruction to allow skipping of instructions in a false branch.

BND Defines the end of one or more branches and checks to determine if any of the branches are true. If not, it includes the program counter offset to the output instruction to enable skipping of unneces-sary instructions.

STOB Defines the start of output branches each contain-ing an output instruction. It contains the pro-gram counter offset to the first output instruc-tion to enable s~ipping of further test instruc-tions when the rung or output branch tests false.

NXOB Defines start of additional output branches and contains the program counter offset to the output instruction in the branch it defines.

~7~ 5 2. Program Control Instructions MCR Defines a master control relay that is included as an output instruction in a rung. When set false, all rungs which follow are set false by STRT
instructions, thus enabling the MCR to control entire blocks of output devices. Rungs which start with an STMC instruction are not affected by the state of the MCR.
LBL Creates a table containing the absolute memory address of targets for JMP and JSR instructions.
See U.S. Patent No. 4,115,853.
JMP A conditional jump to its corresponding LBL
instruction. The jump is made if the rung in which it appears is true.
JSR A call to a subroutine identified by the cor-responding LBL instruction. The return program counter value is saved and the call occurs only if the rung containing the JSR instruction is true.
RET Signals the end of a subroutine and returns to the instruction following the JSR instruction which called the subroutine.
ZCL Defines the start and end of a block of instruc-tions which are to be skipped when the rung con-taining the first ZCL instruction is false.
HALT Unconditional emergency stop of the programmable controller processor with a fault indication.
END Unconditional end of program which resets the watchdog timer and restarts the execution of the control program at its beginning. The END
instruction also defines the set time of the watchdog timer enabling the user to control the maximum allowable scan time.
3. Test ~it Instructions XIC Test the status of a bit in the I/O image XOE table. The rung conditlon remains true if the bit is on (1) and is set false if the bit is off (O).
The instruction includes the address of the I/O
image table word and a bit pointer which identi-fies the particular bit in that word.
XIO Same as XIC and XOE except rung condition is XOD set false when the tested bit is on (1) and remains unchanged when the bit is off (O).
4. Control ~it Instructions OTE If the rung condition is true and the master control relay (MCR) is inactive this instruction sets an indicated bit in the I,~O image tabl~ on (1). Otherwise, the bit is set off (O).
OTL Same as OTE except that the indicated '~it is not set off (O), but is instead left unchanged.

~ ~5~75 OTU If the rung condition is true and the master control relay (MCR) is inactive, tnis instruction resets a bit in the I/O image table to off tO).
Otherwise, no action occurs.
5. Timer/Counter Instructions CTU If the rung condition becomes true and the master control relay (MCR) is inactive, the indicated counter is incremented one count.
CTD Same as CTU but the indicated counter is decre-mented one count.
RTO This retentive timer instruction sets a "done bit"
to on (1) at a preset time interval after the rung condition becomes true. If the rung condition becomes false during the time interval, timing stops but the accumulated time is retained.
RES This instruction resets the accumulated count in an indicated counter or it resets the accumulated time in a retentive timer.
TON This timer instruction sets a "done bit" to on (1) at a preset time interval after the rung condition becomes true. If the rung condition becomes false the done bit is reset to off (O) and the accumu-lated time is reset.
TOF This timer instruction resets a "done bit" to off (O) at a preset time interval after the rung condition becomes false. If the rung condition becomes true, the done bit is set to on (1) and the accumulated time is reset.
6. Arithmetic and Logical Instructions ADD This instruction adds two source operands together and stores the sum in the indicated destination.
The appropriate status register bits (result zero, carry, overflow and sign) are set.
SUB This instruction subtracts the second source operand from the first source operand and stores the difference in the indicated destination. The appropriate status register bits are set.
MULT This instruction multiplies the two source operands together and stores the product in the indicated destination. The appropriate status register bits are set.
DIV This instruction divides the first source operand by the second source operand and stores the quotient at the indicated destination. The appro-priate status register bits are se:.
NEG This instruction subtracts the first source operand from zero and stores the result in the indicated destination. The appropriate status register bits are set.

-~3-SQRT This instruction takes the square root of the first source operand and stores the result at the indicated destination. The appropriate status register bits are set.
MOVE This instruction moves the data at the first source operand to the indicated destination and sets the appropriate status register bits. Data is automatically converted when the source and destination are different data type sections of the data table 623.
CMP This instruction subtracts the second source operand from the first source operand and sets the rung condition false if the comparison fails. The particular comparison to be made is indicated by the destination operand and includes:
Equal Not Equal Greater Than Less Than Greater Than Or Equal To Less Than Or Equal To LIMIT TEST This instruction sets the rung condition false if the first source operand is not between the second source operand and the destination operand.
AND This instruction performs a logical AND on each bit of the first source operand with the cor-responding bits of the second source operand. The results are stored in the destination operand and the appropriate status register bits are set.
OR Same as the AND instruction except a logical OR is performed on each bit.
XOR Same as the AND instruction except an exclusive OR
function is performed on each bit.
NOT This instruction takes the complement of each bit in the first source operand and stores the result in the destination. The appropriate status register bits are set.
7. Transparent Instructions SKIP This instruction is employed to set off portions of the control program which contains nonexe-cutable data. Such data may be, for example, comments which are to be displayed on the terminal 8.

It is an important feature of the present invention that the arithmetic and logic macroinstructions may operate upon data of different types in the data table 623. For example, a binary integer stored in section 5 of the data table 623 may be added ~ ~55~5 (ADD) to a BCD integer stored in section 7, and the result stored as a floating point number in sPction 6. The necessary data conversions are performed automatically and are completely trans-parent to the user.
Referring particularly to Fig. 17, all arithmetic and logic instructions are executed using a set of common routines. The microcode for such an instruction includes microinstructions indicated by process block 805 which set a Q register in the ALU
26 to indicate the "native" data type for the particular opera-tion being performed as well as the source/destination pattern.
The native data type is the type employed by the central proces-sor 2~ to perform the arithmetic or logic operation. In the preferred embodiment, for example, all arithmetic operations are performed with signed, binary integers (SI). The source/
destination pattern is determined by the operation being per-formed. For example, an ADD macroinstruction is accompanied by two source addresses and a destination address (SSD), whereas a square root macroinstruction (SQRT) is accompanied by a single source address and a destination address (SD).
A subroutine is then called to read the indicated source data and convert it to the native data type. As indicated by process block 806, if a file is operated on, FILESTART is called, otherwise, WORDSTART is called. Referring to Fig. 18, the WORDSTART microsubroutine includes instructions indicated by decision block 807 which determine if the rung in which the macroinstruction is located is true. If not, the microroutine is exited and the next macroinstructiGn is executed. Otherwise, the Q register is tested at decision block 808 to determine if a single or double source of data is required Subroutines indicated by process blocks 809 and 810 are called to read the source address(es) from the control program and calculate the memory address(es) of the source data and their data table ~;~7~75 section number. A subroutine indicated by process blocks 811 and 812 is then called to read the source data and convert it to the native data type. The converted source data is stored in ALU
registers S6 and S7 and registers S9 and S10 prior to returning to the calling routine.
Referring again to Fig. 17, the arithmetic or logic function is then performed on this converted source data as indicated at process block 813. The result is stored in ALU registers S9 and SlO and a subroutine indicated by 814 is then executed to convert the result and write it to the destination address. A FILEFINISH
subroutine is called when a file is being operated upon, other-wise a WORDFINISH subroutine is called.
Referring to Fig. 19, the WORDFINISH subroutine calls the ADDRESSIT subroutine as indicated by process block 815 to cal-culate the memory address and data table section number of the destination address contained in the macroinstruction. A
subroutine (STOREIT) indicated at 816 is then called to perform the necessary data conversion on the result in registers S9 and S10 and to write the converted data to the calculated memory address. The system then jumps to a routine for reading the neY.t macroinstruction and mapping to its associated microprogram.
The microcode for many of these subroutines is listed in Appendix B.
Referring particularly to Fig. 20, the transparent data conversions which are made during the execution of arithmetic and logic macroinstructions assume that the operands are stored in the appropriate data table sections. As will be explained in more detail below, the I/O modules 6 and 7 operate to input data of various types from the I/O racks 16 and store such data in the input image table 820. Similarly, the I,/O modules 6 and 7 output data from the output image table 821 directly to the I~O racks 16. The user must transfer the data from the input image table ;7~

820 to the proper section in the data table 623 using the "MOVE"
macroinstruction in the control program. Similarly, altered data in the data table 623 must be transferred to the output image table 821 by a MOVE macroinstruction in order to output it to the proper I/O rack 16. The MOVE macroinstruction is unique in that it does not perform a data conversion when it is transferring data from the input image table 820 or to the output image table 821.
In the example illustrated in Fig. 20, the user's control program may contain macroinstructions which perform the following functions:

MOVE type n data word from input image table to type n data table section;

MOVE type m data word from input image table to type m data table section;

ADD type n data word to type m data word and store result as type o data word;

MOVE type o word to output image table address corresponding to desired I/O rack.
20 It should be apparent that other macroinstructions can be employed to implement any desired control algorithm. Also, regardless of the complexity of this algorithm, the user need not be concerned about data conversions. Input and output circuits of various types may thus be employed in the I/O racks 16 to interface with the many commercially available sensing devices and operating devices used in industrial environments.
The sections of the data table 623 are divided into files.
A file includes one or more data words and it is the smallest data structure supported by the system. Any data word within a file can be separately addressed and it can be either read from the memory module 2 when identified as a source operand, or written to the memory module 2 when identified as a destination operand. When the control program is comprised of macroinstruc-tions which identify single memory words as operands, the 7~

execution time of each separate macroinstruction is relatively short and does not significantly effect the overall scan time of the programmable controller.
The pro~rammable controller of the present invention will perform operations on entire files containing more than one memory word, and the effect of such macroinstructions on the scan time can ~e very significant. For example, and ADD macroinstruc-tion which identifies files as its data sources will sequentially add each word in one source file to each corresponding word in the second source file and store the result in the destination file. If the files are large, the time resuired to execute such a macroinstruction may extend the control program scan time beyond acceptable limits.
This problem is solved by enabling operations to be per-formed on files in a distributed mode of operation. When a fileoperation is performed using the distributed mode, only a portion of each file is operated upon during a single scan through the control program. That is, rather than operating on the entire file each time the macroinstruction is executed, only a few words in the file are operated upon. Because the programmable con-troller repeatedly scans the control program, it performs the operation on additional words in the file during each scan until the entire file is completed. The rate at which the distributed file operation is performed determines the number of file words operated upon during each scan through the control program, and thus the total number of scans required to complete the file operation.
Referring particularly to Fig. 12, when an arithmetic or logic operation is performed on a file, the macroinstruction includes a file control word which indicates the manner in which the file operation is to be executed. The file control word takes one of four possible forms indicated at 825, 826, 827 or 828 in Fig. 12. The control word structures 825 and 827 are single words, whereas the structures 826 and 828 are double word structures which enable expanded addressing capability. The second bit in the first control word indicates if a single word (o) or double word (1) structure is defined. The first bit in the control word indicates if the distributed mode (1) of file operation is defined or not (o). The control word structures 827 and 828 relate to the distributed mode of file operation and they are distinguished by a rate number which indicates the number of file words to be operated upon during each scan through the control program. The contro~ word structures 825 and 826 on the other hand, are distinguished by a mode number which indicates one of three modes in which the file operation can be performed.
All four control word structures 825-828 include a counter pointer which designates a counter structure stored in section 4 of the data table 820. The designated counter is employed as an index register which is added to the source or destination operand address to calculate the absolute memory address of each file word.
There are thus four distinct modes in which file operations can be performed: DISTRIBUTED; ALL; INCREMENTAL; and NONE. For the DISTRIBUTED mode of operation, the operation to be performed on the file will start upon a false to true transition of the rung decision and it wili continue until the entire file is processed. During any single scan through the control program, however, only the number of words indicated by the rate number will be operated upon. An enable bit is set during the file operation to indicate that the operation has started, but is not complete. Upon completion of the entire file, a file done bit is set and when the rung decision then goes false, the counter, file done bit and enable bit are all reset.

~75`575 The ALL mode of operation is similar to the DISTRIBUTED mode of operation, but the entire file is operated upon during the program scan in which the rung decision goes true. Although the file operation is thus performed faster, if the file is large, this mode of operation can significantly increase the control program scan time, and hence degradate the response time of the programmable controller.
The INCREMENTAL mode of operation is similar to the DIS-TRIBUTED mode in that one file word is operated upon during each scan through the control program (i.e. the rate = 1). A sig-nificant difference however, is that each individual operation requires a false to true transition of the rung decision.
The NONE mode of operation performs the indicated function on the file word pointed to by the counter. The counter is not incremented and the operation is performed once during each scan through the control program as long as the rung decision remains true.
The file operations are implemented by employing two distinct microroutines during the execution of macroinstructions.
These are labeled FILESTART and FILEFINISH and they are listed in Appendix C. These microroutines employ a pointer table 825 which is stored in the processor read/write memory 12 and which is illustrated in Fig. 23. The pointer table 825 is initialized at the start of each file operation and it is employed to store the base address of each source file and the destination file as well as the address of the counter which is used as an index into those files. The pointer table 825 also stores a rate number and other data which is employed ~y the FILESTART and FILEFINIS~
microroutines.
Referring particularly to Fig. 1~, the counter structure associated with each file operation includes a control word, preset value word and accumulated value word. The control word ~ 7~S

stores a done bit (D) and an enable bit (E) which are employed to control file operations as will now be explained.
Referring particularly to Fig. 21, the FILESTART micro-routine is called when an operation is to be performed on a file.
As indicated by process block 836 it includes microinstructions which read the file control word portion of the macroinstruction and initialize the pointer table 825 with the indicated data. A
series of tests indicated by decision blocks 827-829 are then performed to determine the mode in which the file operation is to be performed. If in the distributed mode, the rate number from the file control word is loaded into the pointer table 825 as indicated by process block 830. On the other hand, if in the "ALL" mode, the total number of file words is loaded into the pointer table 825, as is indicated by process block 831. In lS either case, if the DONE bit is not set, as indicated at decision block 832, the file operation is performed on the addressed source words as indicated by process block 833.
If the file operation is in the "NONE" mode or the "INCREMENTAL" mode, the indicated logic or arithmetic operation is performed on single file words. If the INCREMENTAL mode is indicated and the DONE bit is not set, as determined at decision block 834, an operation is performed on the addressed file word(s) if the rung decision is true at 835 and the enable bit is reset as indicated at 836. If in the "NONE" mode, the same result occurs if the rung decision is true as indicated at 837 and the enable bit is set. The enable bit is reset at 838 each time the rung decision goes false when in the INCREMENTAL mode, and hence an operation on a single file word(s) is performed after each f~lse-tG-true transitio;l of the rung status. Similar tests of the done and enable bits and the rung decision bit are made in all modes of operation. These tests are indicated by the remaining decision and process blocks in Fig. 21.

When the system returns from the FILESTART microroutine, the logical or arithmetic operation is performed on the file word(s) indicated by the pointer table 825 and the associated counter structure. Following this, a call to the EILEFINISH microroutine is made to determine if the operation is completed or if further file words are to be processed during the current scan through the control program.
Referring particuiarly to Fig. 22, when the FILEFINISH
microroutine is entered the "STOREIT" microroutine is called as indicated at 839 to write the result of the logic or arithmetic operation to the destination address in the data table 623. As explained previously, this microroutine also performs any neces-sary data conversions. If the NONE mode is active as determined at decision block 840 the system returns to fetch and execute the next macroinstruction, otherwise, the counter preset and accumu-lated values are chec~ed at 841 to determine if the file has been completely operated upon. If so, the DONE bit is set at 842 and the next macroinstruction is fetched and executed. If the file has not been completely operated upon, t~e rate counter in the pointer table is decremented at 843 and tested at decision bloc~
844 to determine if further file words are to be operated upon during this program scan. If not, the next macroinstruction is executed, otherwise, the next source file word, or words, are read from the data table 623 and the next destination address is calculated as indicated at 845. The system then returns to the microroutine from which it was called to perform another opera-tion on the addressed file words.
System I~O Scanner Module The system I/O scanner 7 is a single board mi_roproceC.sor based module which directly interfaces the system backplane bus l with from one to four serial I~O buses which each connect to one ~ 5 ~'t S

or more I/O racks 16. The module 7 will also support communica-tions with the front panel interface 11, and 'hrough a connector on the front panel interface 11, the system I/O scanner module 7 will also support the terminal 8. Indeed, although the system I/O scanner module 7 may be employed along with the other system modules as shown in Fig. 1, it is contemplated that the module 7 may also be configured as the sole means for performing I/O
functions on small systems containing only a CPU module 3, a memory module 2 and a front panel interface 11.
Referring particularly to Figs. 1 and 7, the system I/O
scanner module 7 is structured about a sixteen-bit data bus 400 and a sixteen-~it address bus 401 which are controlied by a microprocessor circuit 402. The buses 400 and 401 are coupled to the system backplane bus 1 through a backplane interface circuit 403 and when data is to be transferred to or from the system backplane bus 1, the backplane interface circuit 403 makes a request to a DMA circuit 404 through a BPR~Q control line 405.
The DMA circuit 404 acknowledges the request through a BPACK
control line 408 when the backplane interface circuit 403 can have access to the buses 400 and 401 to perform its data transfer.
The DMA circuit 404 responds not only to requests from the backplane interface circuit 403, but also to similar requests received from two serial input/output circuits (SIOs) 406 and 407. The two SIOs 406 and 407 provide an interface to four serial I/O buses 409, 410, 411 and 412 which connect to I/O racks 16. The two channels in each SIO 406 a~d 407 are driven ~y clock lines 413 which connect to a clock circuit 414. When the SIOs 406 or 407 ~re ready to transmit a message or have received a message from a serial port 409-412, they generate a request signal to the DMA circuit 404 through a bus 415. The DMA circuit 404 generates a DMA request to the microprocessor 402 through a ~175~75 request line 416, and when the microprocessor 402 completes execution of its current instruction, it grants the DMA request through a line 417. The DMA circuit 404 then takes control of both the buses and the SIOs 406 and 407 to perform the message data transfer. When an end-of-message character is received by an SIO 406 or 407, it generates an interrupt request on control line INT to the microprocessor 402. As will be explained below, the microprocessor 402 responds to the interrupt by transferring the incoming message to the proper module in the system and by sending a message to one of the I/O racks 16.
Referring particularly to Fig. 7, a third SIO 418 also connects to the module data bus 400 and is driven through a palr of the clock lines 413. The SIO 418 forms part of an optional circuit 419 which interfaces the module 7 to the front panel 11 through a pair of serial ports 4~0 and 421. Both serial ports 420 and 421 connect to lines in the system backplane bus 1 which in turn connect to the ribbon connector leading to the front panel. Serial port 420 exchanges data at 4800 baud with the processor in the front panel circuit 11 and the serial port 421 exchanges data through an RS 232C connector which is mounted on the front panel. The SIO 418 is interrupt driven and when data is received, the microprocessor 402 is interrupted and vectored to the proper interrupt service routine.
The microprocessor 402 operates in response to instructions which are stored in a read-only memory (PROM) 425. These include interrupt service routines which are executed in response to interrupt requests on the INT control line, programs 'or execut-ing tasks and communicating through the system backplane 1 with other modules in the system, and programs for configuring and driving the SIOs 406, 407 and 418.
The primary function of the system I/O scanner module 7 is to couple input/output data between the I~O image and data table ll ~ ss~s 12 in the CPU module 3 and the I/0 racks 16 which connect to the scanner module 7. The speed with which the scanner module 7 performs this function is an important factor in the operation of the programmable controller system and the preferred embodiment of the invention provides a unique structure to accomplish this.
More specifically, a random access memory (RAM) 426 connects to the module buses 400 and 401, and in addition to providing work space for the microprocessor 402, it stores a copy of the output portion of the CPU module's I/0 image table memory 12. The microprocessor 402 continuously updates the image table in the RAM 426 by reading output status data from the CPU module 3 and reading input status data from the I/0 racks 16. The micro-processor 402 also continuously writes its output image table data to the I/0 racks 16 and writes its input status data to the CPU module 3. This continuous updating, or "refreshing", of the I/0 devices and associated I/0 image tables is done at a relatively low priority and it is performed regardless of whether or not changes are occurring in the status of input/output devices.
Superimposed on this I/0 refresh process is a high speed I/0 update process which couples data indicative of changes in input/output status data. When data is written to the image table in the RAM 426 by the CPU module 3 (via the backplane interface 403) a change detect circuit 427 is enabled and stores an indication of which line in the RAM image table 426 was changed. The microprocessor 402 operates to repeatedly test the change detect circuit for such changes in I/0 status data, and when a change is detected, to rapidly relay the detected change on to the I/0 rack 16. In this manner, changes in status data are rapidly processed while the continuous I/0 refresh process of all I/0 points is carried on in the background.

1`175~75 The sys'em I/O scanner module 7 is thus structured to quickly relay any changes in output points dictated by the CPU
module 3 on to the proper I/O rack 16 and to relay any changes in input points detected by the I/O racks 16 on to the CPU module 3.
Secondarily, the I/O scanner module 7 may be employed to inter-face with the terminal 8 and the front panel 11 and it may be employed to initialize the memory module 2 during power-up. For a more detailed description of its structure, reference is made to co-pending U.S. Patent application Serial No. 313,365 filed on October 21, 1981 and entitled "Modular Programmable Controller."
Referring particularly to Figs. 1, 7, and 14A, the I/O
scanner module 7 is responsible for initializing the programmable controller system during power-up, and for performing tasks associated with its six serial ports and its backplane interface.
These functions are coordinated by a scheduler program 650 which is entered from any of four interrupt service routines 651-654 or from any of eight task programs 655-662. The scheduler 650 determines which of the tasks 555-662 should be executed by examining a linked list of task control blocks which are stored in the RAM 426 and indicated at 663. If more than one task is to be executed, the scheduler selects that task having the highest priority. That is, the scheduler examines the task control blocks 663 to determine if the I/O scan task 655 is to be executed, then it determines if the block transfer task 656 is to be executed, followed by the front panel serial driver 657, the backplane driver 658 and the timer utility 659. One of the three tasks 660, 661 or 662 is then given pr.ority and the cycle repeats.
The task contrsl blocks 663 store bits of data which indi-cate those tasks that are ready to be executed. These bits may be set by any of the tasks or by one of the interr~pt service ~175~75 routines 651-654. For example, when the real time clock inter-rupts every one millisecond, the interrupt service routine 651 is executed to make an entry into the task control block 663 which indicates that the timer utility task 659 is to be executed. The scheduled 650 is then entered, and if no other tasks are ready to run, or if the timer utility 659 has priority, the task 659 will then be executed. An interrupt from the front panel 11 or the serial port on the front panel 11 is serviced by the routine 654 which sets a bit in the task control block 663 for either the front panel task 661 or serial port task 662. When these tasks 661 or 662 are then executed, they interpret commands and may in turn set a bit in the task control block for the front panel driver task 657 which transmits data back to the front panel 11.
When an interrupt occurs as a result of data received from one of the I/O racks 16, the service routine 653 is executed.
This I/O rack interrupt service routine 653 not only determines which I/O rack 16 requires service, but it also determines if a block transfer of data from the I/O rack 16 has occurred. If so, the block transfer task 656 is enabled; otherwise, the I/O scan task 655 is enabled. The block transfer function is described in more detail in U.S. Patent No. 4,413,319 which issued on November 1, 1983 and which is entitled "Programmable Controller for Executing Block Transfer With Remote I/O Interface Racks".
The I/O scan task 655 will now be described in connection with a power-up routine 664.
Referring particularly to Figs. 1, 7 and 14B, the power-up routine in the I/O scanner module 7 is responsible for initializing the programmable controller system during power up.
As indicated by process block 700, the first task, however, of the I/O scanner module processor 402 is to execute instructions which initialize the I/O scanner module 7 itself. This includes initialization of the SIOs 406, 407 and 419, the clock circuit 7~

414, the change detect circuit 427 and the RAM 426. The proces-sor 402 then executes instructions indicated by process block 701 to read from each backplane bus module slot to determine what modules are present in the system and which 256K address space S they occupy. Instructions indicated by decision blocX 702 are then executed to determine if an operable programmable controller is configured. If not, the system shuts down.
The I/0 scanner module 7 then initializes the sections 620-623 of the memory module 2. More specifically, it creates access control blocks 621 for each module connected to the backplane bus 1 as indicated by process block 703 and it sets up the module status areas 622 as indicated by process block 704.
The I/0 scanner module 7 also sets the system status counter 606 to the number of modules which require initialization and i-t sets the I/0 prescan counter 610 to the number of I/0 scanner modules and I/0 bus interface modules present in the system. The power-up routine is then exited and the I/0 scan task 655 is entered to complete system initialization.
Referring particularly to Fig. 14C, the I/0 scan task 655 is entered initially from the power-up program 664. As indicated by process block 705, its first function is to perform an I/0 pre-scan of the I/0 racks 16 which are connected to the I/0 scanner module 7. More specifically, the adaptors 17 on each I/0 rack 16 are interrogated to determine the number and nature of each I/0 circuit in the rack 16. Initialization messages are then created and stored in a message queue in the RAM 426 and the module 7 then checks to determine if it can begin the I/0 prescan, as indicated by decision block 706.
The I/0 scanner module 7 then enters a loop in ~.hich messages are output to all I/0 racks 16. These initial messages turn all output devices off, and in response, messages are received from each I/0 rack 16 which contain data concernin~ the ~7~ 5 state of all input devices. When this I/0 prescan is compLete as determined at decision block 707, the I/0 scanner module 7 decrements the I/0 prescan counter 610 in the memory module 2 to notify the CPU module 3 that initialization is complete.
Referring particularly to Figs. 14A and 14C, each time the I/0 scanner module 7 receives a message from an I/0 rack 16, an interrupt is generated and the I/0 rack interrupt routine 653 is executed to queue up the I/0 scan task 655. When the I/0 scan tas~ is subsequently entered, a check is made at decision block 711 to determine if input data was received. If it was, this data is written into a message queue for the backplane driver task 658 and that task is enabled to write the data to the I/0 image table in the CPU module RAM 12 as indicated at process block 712. After the input data has been processed, the I/0 scanner module 7 sends output messages to the I/0 racks 16. As indicated by process block 716, the message queue for the I/0 scan task is examined to determine the next I/0 rack 16 to receive refresh output data from the I/0 scanner module's output image table. In addition, the change detect RAM 475 is examined to determine if any outputs involving the same I/0 rack 16 have been changed. This is accomplished by instructions indicated by decision block 717, and when "change" data is found, it is loaded into the output message queue as indicated by process block 718.
As indicated by process block 719, the refresh data is loaded into the output message queue, and it, along with any change data, is sent to the proper I/0 rack 16. A test is made at decislon block 720 to determine if this is part of the I/0 prescan process, and if not, the I/0 scanner module 7 returns to the scheduler to perform other tasXs.
It should be apparent that in the preferred embodiment of the invention described herein ~he I~0 scanner module 7 performs a substantial portion of the system initialization during power ~ ~L7~i7~

up. It is also possible to program the peripheral processor module 5, the system I/0 bus interface module 6, or the CPU
module 3 to perform the system initialization functions. It is necessary, however, that one system module initialize the memory S module data structures, since it is these data structures which enable the various sy~tem modules to operate in a coordinated manner as a programmable controller.
Svstem Communications Referring particularly to Figs. 1, 9C and 16, communication between the modules on the backplane bus l is established using the module status blocks 622 stored in the memory module 2. The CPU module 3, the system I/0 interface module 6, the peripheral processor module 5, the system I/0 scanner module 7 or the com-munications network module 4 may originate, or send, a message o~er the backplane bus 1 and any of these same modules may be the designated destination, or receiving, module. As described above with respect to the system I/0 scanner module 7, these modules may perform more than one task, and hence the message may origi-nate from a part cular task within one module and be received by a particular task in another module. The proper transmission and receipt of messages is carried out by a message handler task on each module which will ~ow be described in more detail.
Referring particularly to Figs. 9C and 16, when a sending module 800 wishes to send a message to another module, 802, its message handler creates a parameter block 801 and writes the address of that block 801 into the status block 622 for the receiving module 802. More specifically, the sending module message handler loads the parameter block address into the "message address" portion of the module status ~lock 622 at the location indicated by its "next-in pointer". The sending module message handler then increments the next-in pointer number and -h~-generates the interrupt address of the receiving module 802 on the system backplane bus 1.
The receiving module 802 includes a backplane message inter-rupt routine which is executed when the receiving module's interrupt address appears on the backplane bus 1. This routine examines its module status block 622 stored in the memory module 2 to obtain the backplane address indicated by the "next-out pointer". Using this address the receiving module 802 reads the parameter block 801 from the sending module's memory, writes a copy 803 in its own memory, and updates the next-out pointer.
The task in the receiving module for which the message is intended is notified of the message, and when that task is subsequently executed, it responds to the message. One response is to reply to the message by altering the receiving module parameter block 803, placing the address of the modified block 803 in the sending module's message block 622, and generating the sending module's interrupt address on the system backplane bus 1.
The sending module services this interrupt by copying the receiv-ing module parameter block 803 back to its own memory at 801 where the appropriate sending module task can operate on it. Two way communications is thus established and is "transparent" to the tasks on each module.

ComPonent Appendix - Central Processor Reference No. Description 54, 89, 189 Quadruple D-type flip-flops 74LS175 manufactured by Texas Instruments, Inc.

1~L75S'75 33 Microprogram Controller AM2910 manufactured by Advanced Micro Devices, Inc.

42 2Kx4 PROM 82S185 manufactured by Signetics, Inc.

31, 41 2Kx8 PROM 82Sl91 manufactured by Signetics, Inc.

32, 47, 58, 116, 117, 130 Octal D-type transparent 131, 132, 139, 73 flip-flops 74LS374 manufactured by Texas Instruments, Inc.

39 Octal D-type flip-flop 74LS273 manufactured by Texas Instruments, Inc.

46, 48, 80, 161, 112 Octal buffers & line drivers 74LS244 manufactured by Texas Instruments, Inc.

43 Two 32x8 PROMS 82S123 manufactured by Signetics, Inc.

26 Four 4-bit bipolar microprocessor slices AM2903 manufactured by Advanced Micro Devices, Inc.

51 Data selector/Multiplexer 74LS151 manufactured by Texas Instruments, Inc.

~3L7S57S

109, 113, 138 Octal D-type transparent Latch 74LS373 manufactured by Texas Instruments, Inc.

140, 63, 76 Four synchronous 4-bit counters 74 LS163 manufactured by Texas Instruments, Inc.

67 Dual 4-bit binary counters 74LS393 and Dual 4-bit decode counters 74LS390 manufactured by Texas Instruments, Inc.

83-88 Dual D-type positive edge triggered flip-flops 74S74 manufactured by Texas Instruments, Inc.

102 8-bit addressable latch 74LS259 manufactured by Texas Instruments, Inc.

91 8-line-to-3-line priority encoder 74LS148 manufactured by Texas Instruments, Inc.

105 Two 32x8 PROMs 82S123 manufactured by Signetics, Inc.

150 Two 4-bit magnitude comparators 74S85 manufactured by Texas Instruments, Inc.

1;~7~ii575 184, 185 Four-bit shift registers 74S194 manufactured by Texas Instruments, Inc.

196 Synchronous 4-bit counter 74LS163 manufactured by Texas Instruments, Inc.

Appendix A

Microfield Definition Mnemonic Control Lines & Device DescriPtion JUMP3 microsequencer 33 If register counter is not zero and condition is false, load PC from stack. When register counter is zero and condition is false, load PC
from bus 44. If condition is true, increment PC.
CONT microsequencer 33 Increment PC.
LOOP microsequencer 33 If condition is true, increment PC. Otherwise put stack in PC.
LOAD microsequencer 33 Load register counter from bus 44.
RET microsequencer 33 Pop stack and load in PC.
. AGAIN microsequencer 33 Loop until register counter is zero then load PC from bus 44.
BACK microsequencer 33 Same, but load PC from stack.

1iL755~S

JUMP2 microsequencer 33 If condition true, load PC
from bus 44. Otherwise, load PC from register counter.
VECT microsequencer 33 Input microaddress from bus 44.
CALL2 microsequencer 33 Same as JUMP2, but save PC on stack.
PUSH microsequencer 33 Load register counter from bus 44, push PC on stack.
JUMP microsequencer 33 Input microaddress from bus 44.
MAP microsequencer 33 Input microaddress from bus 44.
CALL microsequencer 33 Push address to stack, get target from bus 44.
RESET microsequencer 33 Force PC to zero, clear stack pointer.

PIPE data selector 45 Select data from bus 44.
ALV16 data selector 45 Select data from bus 44 and bus 40 and put on bus 44.
MACRO data selector 45 Select data from bus 44 and ALU port 30.
IVECT Interrupt interface 52 Enable microaddress on to bus 44.
ALU Gates 56 Couple microaddress from ALU
26 to bus 44.
MAP MAP ROM 41 Enable microaddress on to bus 44.

VECT VECTOR ROM 42 Enable microaddress on to bus 44.

_ INSTR Gates 46 Couple macroinstruction to ALU
port 27 DATA Gates 48 Couple data from bus 22 to ALU
port 27.
RAM Gates 48 Couple data from bus 22 to ALU
port 27.
BFLOP Swap high and low bytes in ALU
registers.
TIME control line 75 Read real time clock latch 73.
TIME control line 81 Read scan coun.er gates 80.
FLAGS Read status of flags saved in register.

ADDR address latch 47 Store address data in latch 47.
BACKL control line 135 Store LSB of address in latch 131.
FETHI control line 144 Store MSB of address in latch 139.
BACKH control line 136 Store MSB of adcress in latch 132.
FETC~ control line 141 Load address in macro counter 140.

DATA data latch 58 Store data in latch 58.

BACKD control line 133 Store data in latch 130.
IRES control line 108 Enable decoder 107 to reset interrupt SYST Control backplane lines.

TIME control line 77 Store time in scan counter 76.

IMASK control line 103 Enable addressable latch 102.

ILOAD control line 123 Load prefetched macro in register 39 _ IMM Gates 57 Couple macroinstruction data to ALU port 28.

MASK Bit Pointer ROM 43 Generate bit pointer mask to ALU port 28.

NMASK Pit Pointer ROM 43 Generate inverted bit pointer mask.

HOLD control line 185 Activate backplane HOLD line 175.

1~75575 BWH control lines 185 Activate backplane write and 187 line and hold it.

BRH control lines 185 Activate backplane read and 186 line and hold it.

WRITE control line 164 Write data on CPU bus 22.

READ control line 166 Read data on CPU bus 22.

BACKW control line 187 Write data on backplane bus 1.

BACKR control line 186 ~ead data on backplane bus 1.

_ ZER Set carry to zero.

ONE Set carry to one.

ZFL Set carry to ALU zero flag state.

CAR Set carry to carryout of previous ALU operation.

_ ~7~i~75 TRUE STATUS MUX 51 Was the result true?

FALSE STATUS MUX 51 Was the result false?

INTER STATUS MUX 51 Is an interrupt request present?

PARITY STATUS MUX 51 I s a parity error indicated?

CARRY STATUS MUX 51 Was there a carry?

NCARR STATUS MUX 51 Was there no carry?

OVER STATUS MUX 51 Was there an overflow?

MOVER STATUS MUX 51 Was there no overflow?

MINUS STATUS MUX 51 Was the result minus?

PLUS STATUS MUX 51 Was the result not minus?

ZERO STATUS MUX 51 Was the result zero?

NZERO STATUS MUX 51 Was the result not zero?

5~ii75 APpendix B

Micro~rograms for Selected Macroinstructions Label Definitions FETCH Microroutine for fetching next macroinstruction.
FLUSH-PIPE Throw away prefetched macroinstructions.
DUMP -PIPE Skip long macroinstructions.
SAVE67 Save ALU registers 6 and 7.
RESTR67 Restore ALU registers 6 and 7.

OUTPUT Start of output image table.
INPUT Start of input image table.
SCANNERMAP Map of I/O scanners.
JUMPTABLE Table of target addresses for jumps.
SUBRLABELS Table of target addresses for JSRs.

ENOUGHTIMES Initial program scan counter.
FIRSTTIME Flag set to one during first scan.
TIMEBASE Type of timer code storage.
FETCHISAVE Most significant bits of fetch counter.
FETCHI-FLSE Most significant bits of fetch counter.
WORDRWFLG Flag.
MSFCSUBCTR Counter for 1 millisecond interrupt.
DTXPOINT Table pointers for active data.
PGADDR Active program counter.
SCRATCH General purpose scratch pad.
STCKSTRT Stack used by branch control instructions.

l~f~5s7s SYSPARFLG Parity bit in system status register.
SYSDOGFLG Watchdog bit in system status register.
SYSBPLELG Backplane error bit in system status register.
SYS-STATSH System status register in address bytes.
CPU-OPER Flag indicating CPU is executing control program.

117~S75 Rung Control Macroinstructions ;BRANCH START (BST) ;THIS INSTRUCTION HAS THE OFFSET FROM THE NEXT INSTRUCTION TO THE
;NEXT NXB/BND INSTRUCTION. T~ ADDRESS OF THE NEXT CONDITIONAL
;INSTRUCTION IS SAVED ON A LIFO STACK ("PUSHED"). THE ADDRESS
;OF-THE NEXT NXB/BND IS CALCULATED AND SAVED. THE OR ACCUMULATOR
;IS INITIALIZED FALSE (0). NO ADX IS POSSIBLE FOR THIS
;INSTRUCTION.
;REGISTER USAGE:
; SO-PROGRAM COUNTER
; Sl-ADDRESS OF NEXT CONDITIONAL OR NXOB
; INSTRUCTION
; S4-OR ACCUMULATOR
; S12-9 OPERAND BITS CALCULATED DURING
; INSTRUCTION FETCH.
; S13-LIFO STACK POINTER
BST-MAP
DATA N=Sl ;SAVE OUTPUT ADDRESS ON STACK
ADDR S13-S13-#1 Sl-S12 AND #OFF WRITE ;Sl=8 DISPLACEMENT BITS
;WRITE OUTPUT ADDRESS ON STACK
Sl-S01S1 ;CALCULATE AND SAVE ADDR. OF
;NEXT NXB/BND INSTRUCTION
;BY ADDING THE DISPLACEMENT
;TO THE PROGRAM COUNTER.
S4=0, JUMP FETCH ;SET OR ACCUMULATOR FALSE.
;GO GET THE NEXT INSTRUCTION.

;NEXT BRANCH (NXB) ;THIS INSTRUCTION EXAMINES THE RUNG CONDITION FROM THE PREVIOUS
;BRANCH. IF TRUE, THE PROGRAM COUNTER IS SET TO THE ADDRESS
;OF THE NEXT NXB/BND. IF FALSE, IT IS SET TRUE FOR THE NEXT
;BRANCH, THE OR ACCUMULATOR IS LEFT FALSE, AND THE "PROGRAM
;COUNTER IF FALSE" REGISTER IS SET TO THE ADDRESS OF THE NEXT
;NXB/BND. THE DISPLACEMENT IN THIS INSTRUCTION IS FROM THE NEXT
;INSTRUCTION TO THE NXB/BND.
;REGISTER USAGE:
; S0-PROGRAM COUNTER
; S1-ADDRESS OF NEXT NXB/BND
; S3-RUNG DECISION (0=FALSE, FFFF=TRUE) ; S4-OR ACCUMULATOR (O=FALSE, FFFF=TRUE) ; S12-9 OPERAND ADDRESS BITS CALCULATED DURING
; INSTRUCTION FETCH.
NXB-MAP
Sl=S12 AN~ #OFF ;S1-DISPLACEMENT
Sl=SO+Sl jCALCULATE ADDRESS OE NEXT
;NXB/BND IN S1.
S4=S4 OR S3, LOAD FLUSH-PIPE ;OR ACCUM=OR ACCUM OR RUNG DEC.
;SETUP FOR 2-WAY JUMP.
S3=HIGH, JUMP2 FETCH ZERO ;SET RUNG DECISION TRUE. GET
;NEXT INSTRUCTION IF OR ACCUM.
-. ;IS ST.LL FALSE. OTHERWISE
;GO DIRECTLY TO THE NEXT
;NXB/BND INSTRUCTION BY
jJUMPING TO FLUSH-PIPE.
_ 117~57~

;BRANCH END (BND) ;THIS INSTRUCTION EIRST CHECKS THE STACK POINTER AND, IF 'ln~
;STACK IS EMPTY, FORCES A FALSE RUNG DECISION. OTHERWISE THE
;STACK IS POPPED TO RESTORE ln~ ADDRESS OF THE NEXT CONDITIONAL
;INSTRUCTION AND THE RUNG DECISION IS MADE EQUAL TO THE RUNG
;DECISION OF THE LAST RUNG OR'ED WITH THE RESULTS OF THE
;PREVIOUS BRANCHES (THE OR ACCUMULATOR). IF THE BRANCH RESULT
;IS TRUE (FFFF), THE NEXT INSTRUCTION IS EXAMINED. OTHERWISE
;THE NEXT CONDITIONAL INSTRUCTION IS FETCHED.
;A LIFO POP IS DONE BY READING FROM THE MEMORY ADDRESSED BY T~E
;STACK POINTER, AND THEN INCREMENTING THE STACK POINTER.
;ON INPUT, S3 IS THE DECISION OF THE LAST BRANCH. ON OUTPUT, IT
;IS THE RESULT OF THE ENTIRE BRANCH.
;REGISTER USAGE:
; SO-PROGRAM COUNTER
; Sl-ADDRESS OF NEXT CONDITIONAL INSTRUCTION
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) ; S4=OR ACCUMULATOR (O=FALSE, FFFF=TRUE) ; S13=LIFO STACK POINTER
BND-MAP
N=S13=#STCKSTRT ;IF STACK EMPTY, FORCE A
;FALSE RUNG DECISION
ADDR N=S13, JUMP FORCE-FALSE ;BY JUMPING TO FORCE-FALSE.
CARRY
Sl=RAM READ ;RESTORE ADDRESS OF OUTPUT
;INSTRUCTION FROM STACK.
S3=S3 OR S4, LOAD
FLUSH-PIPE ;RUNG DEC=RUNG DEC OR OR ACC.
;SETUP FOR 2-WAY JUMP.
S13=S13+1, JUMP 2 FETCH NZERO ;INC STACK POINTER TO FINISH
;POP OPERATION.
;FETCH NEXT INST. IF RUNG IS
;STILL TRUE. OTHERWISE
;GO DIRECTLY TO THE NEXT
;CONDITIONAL INSTRUCTION BY
;JUMPING TO FLUSH-PIPE.
FORCE-FALSE
S3=0, JUMP FLUSH-PIPE ;FORCE RUNG DECISION FALSE.
;FETCH THE NEXT CONDITIONAL
;INSTRUCTION BY JUMPING TO
;FLUSH-PIPE.

;START OUTPUT BRANCH (STOB) jTHIS INSTRUCTION HAS THE OFFSET FROM THE NEXT INSTRUCTION TO
;THE FIRST OUTPUT INSTRUCTION. AN NXOB OR OBND OF RUNG MUST
;IMMEDIATELY FOLLOW THE OUTPUT INSTRUCTION. THE STOB PUSHES THE
;RUNG DECISION ON THE STACK FOR THE FOLLOWING NXOB'S. IF THE
;RUNG DECISION IS FALSE THE PC IS SET TO THE OUTPUT, OTHERWISE
;THE NEXT INSTRUCTION IS EXECUTED.
;REGISTER USAGE:
; SO-PROGRAM COUNTER
; Sl-ADDRESS OF OUTPUT INSTRUCTION
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) ; S12-9 OPERAND ADDRESS BIT~ CALCULATED DURING
; INSTRUCTION FETCH
; S13-LIFO STACK POINTER

1~7~;575 STOB-MAP
Sl=S12 AND #OFF ;Sl=DISPLACEMENT
DATA N=S3 ;SET UP STACK DATA
ADDR S13=S13-1 jSET UP STACK ~DDRESS
LOAD FLUSH-PIPE WRITE ;WRITE RUNG DECISION ON STACK.
;SETUP FOR 2-WAY JUMP.
Sl=SO+Sl, JUMP2 FETCH
NZERO ;CALCULATE ADDRESS OF
;OUTPUT IN Sl BY ADDING THE
;OFFSET TO THE PC.
;FETCH NEXT INSTRUCTION IF
;RUNG DECISION IS TRUE.
;OTHERWISE GO DIRECTLY TO
;Tn~ NEXT CONDITIONAL INST.
;BY JUMPING TO FLUSH-PIPE.

;OUTPUT BRANCH END ~OBND) ;THIS INSTRUCTION REMOVES THE RUNG DECISION SAVED BY 1~ STOB
;FROM THE STACK. THIS RECALLS THE DECISION OF A HIGHER LEVEL IN
;NEXTED OUTPUT BRANCHES
;REGISTER USAGE:
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) ; S13-LIFO STACK USED BY BRANCH INSTRUCTIONS
DBND-MAP
ADDR N=S13 ;SET UP FOR STACK POP
S3-RAM READ ;READ SAVED RUNG DECISION
S13=S13+1, JUMP FETCH ;POP STACK, GET NEXT
;INSTRUCTION
_ Program Control Instructions ;MASTER CONTROL RELAY (MCR) ;THIS IS THE OUTPUT INSTRUCTION THAT GENERATES THE VALUE OF Tn:
;MCR REGISTER (=FFFF TRUE, =OOOO FALSE). THIS INSTRUCTION IS
;EXECUTED UNCONDITIONALLY EACH TIME IT IS ENCOUNTERED. THE
;INSTRUCTION COPIES THE PRESENT STATE OF THE RUNG DECISION INTO
;THE MCR DECISION REGISTER.
;REGISTER USAGE
; S3-RUNG DECISION (OOOO=FALSE, FFFF=TRUE) ; S8-STATE OF MCR (OOOO=FALSE, FFFF=TRUE) MCR-MAP
S8-S3, JUMP FETCH ;COPY RUNG DECISION TO MCR
STATE
_ _ ;JUMP TO TARGET (JMP) jTHIS INSTRUCTION EXECUTES A CONDITIONAL JUMP TO THE ADDRESS
;SPECIFIED BY THE VALUE OF THE TARGET
JUMP-MAP
JUMP FETCH

1~755'75 ..
;CALL SUBROUTINE AT TARGET (CALL) ;THIS INSTRUCTION EXECUTES A CALL TO THE SUBROUTINE AT THE
;ADDRESS SPECIFIED BY ln~ VALUE OF THE TARGET
CALL-MAP
JUMP FETCH
_ Bit Instructions ;XIC ON IMATE TABLE (XIC) ;BIT TEST, THE RUNG DECISION REMAINS TRUE (FFFF) IF THE BIT IS ON
;AND IS SET FALSE (O) IF THE BIT IS OFF.
;REGISTER USAGE:
; SO-PROGRAM COUNTER
; Sl-ADDRESS OF OUTPUT INSTRUCTION.
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) XIC-MPA
N=RAM AND MASK READ ;TEST BIT FROM IMAGE
N=Sl-SO, JUMP FETCH NZERO ;JUMP IF RUNG STAYS TRUE
S3=0, JUMP FETCH ZERO ;SET RUNG COND FALSE, ;JUMP IF FETCH NEXT INST
N=Sl-SO-l ;TEST FOR SKIP ONE INST
EXAMINE
ILOAD SO=SO+l, JUMP FETCH ZERO ;SET PC TO SKIP ONE, DO A
;DUMMY ILOAD, FETCH OUTPUT
N=Sl-SO
FETCH SO=Sl, JUMP FETCH PLUS ;SET FETCH COUNTER TO OUTPUT
ADDR N=#FETCHISAVE ;HIGH COUNT MUST ALSO BE
;CHANGED
FETHI N=RAM, JUMP FETCH READ ;SET HIGH FETCH COUNT GOTO
;FETCH
_ ;OUTPUT ENERGIZE (OTE) ;IF THE RUNG DECISION IS TRUE, THE BIT ADDRESSED IS SET TO A 1, ;OTHERWISE IT IS RESET TO A O. THIS INSTRUCTION HAS NO EFFECT ON
;THE RUNG DECISION. THE DATA TABLE LOCATION IS ONLY UPDATED IF
;THERE IS A CHANGE IN THE ADDRESSED BIT. NOTIFICATION OE OUTPUT
;CHANGES IS DONE BY SAVING ALL CXANGES FOR A SLOT AND THEN DUMPING
;THE CHANGES FOR THAT SLOT TO Tn~ SCANNER WHEN THE NEXT OUTPUT
;INSTRUCTION REFERENCES A DIFFERENT SLOT.
;OTL ENTERS AT SET. OTU ENTERS AT RESET.
;REGISTER USAGE:
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) ; S6-~OLDS PREVIOUS SLOT NUMBER
; S7-HOLDS PREVIOUS SLOT DATA
; S12-9 OPERAND ADDRESS BITS CALCULATED DURING
; INSTRUCTION FETCH.
; Q-SCRATCH REGISTER.
OTE-MAP
N=S3 ;TEST RUNG CONDITION
S14=RAM, JUMP SET NZERO
- READ ;GET DATA, SET ON IF RUNG
;TRUE

~75~75 RESET ;TURN BIT OFF
DATA Q=S14 AND NMASK, JUMP OTE-COMMON
SET ;TURN BIT ON
DATA Q=Sl4 OR MASK
OTE-COMMON
N=S6 WRITE ;TEST FOR PREVIOUS CHANGE
;WRITE I/O IMAGE TO CPU RAM
SET-FLAG
N=S14 XOR Z, JUMP TEST
PLUS ;JUMP IF PREVIOUS CHANGE
;CHECK EOR CURRENT CHANGE
S6=HIGH, 3UMP FETCH ZERO ;SET FLAG TO NO CHANGE
;JUMP IF NO CHANGE
S6-S12, JUMP FETCH ;SETCHANGE DETECTED FLAG
;JUMP TO EETCH
;HANDLE PREVIOUS CHANGE
TEST
BACKD N=S7 ;SET LAST SLOT DATA IN BPLANE
;LATCH
N=S6 XOR S12 ;CHECK FOR SAME SLOT AS LAST
;CHANGE
S=7Q, JUMP FETCH ZERO ;JUMP IF SAME SLOT AS LAST
;SAVE PRESENT SLOT DATA
LL6=S6 + O100 ;FIND INDEX TO SCANNER LOOKUP
;TABLE
ADDR S6=S6-#1 ;SET ADDRESS IN LOOKUP TABLE
BACKH N=RAM READ ;GET AND SET HIGH ADDRESS OF
;SCANNER
ADDR N=S6 + 1, JUMP TESTl ZERO ;JUMP IF NO SCANNER ASSIGNED
;TO SLOT
BACKL N=RAM READ ;GET AND SET LOW ADDRESS OF
;SCANNER
CONT BACKW ;WRITE DATA TO SCANNER
TESTl N=S14 XOR Q, JUMP
SET-FLAG ;TEST FOR CURRENT CHANGE
;SET UP FLAGS FOR NEXT RUNG

;OUTPUT LATCH (OTL) ;THIS IS THE BIT LATCH INSTRUCTION. IF THE RUNG DECISION IS
;TRUE, EXECUTION CONTINUES IN THE OT3 MICROROUTINE. OTHERWISE, ;NO ACTION OCCURS, AND THE NEXT INSTRUCTION IS EXECUTED. THIS
;INSTRUCTION HAS NO EFFECT ON THE RUNG DECISION.
;REGISTER USAGE:
; SAME AS OTE MICROROUTINE
OTL-MAP
N=S3, LOAD SET ;SETUP FOR 2 WAY JUMP.
S14-RAM, JUMP2 FETCH
ZERO READ ;READ THE OUTPUT IMAGE
;FROM RAM INTO S14.
;IF RUNG IS FALSE, GET
;NEXT INSTRUCTION
;ELSE TURN THE OUTPUT
;ON BY JUMPING TO SET
;IN THE OTE MICRO-;ROUTINE

1~7SS75 ;OUTPUT UNLATCH (OTU) ;THIS IS THE BIT UNLATCH INSTRUCTION, IF THE RUNG DECISION
;IS TRUE, EXECUTION CONTINUES IN THE OTE MICROROUTINE TO
;RESET 1~ ADDRESSED BIT TO A 0. OTHERWISE, NO ACTION OCCURS, ;AND THE NEXT INSTRUCTION IS EXECUTED. THIS INSTRUCTION HAS
;NO EFFECT ON THE RUNG DECISION
;REGISTER USAGE:
; SAME AS OTE MICROROUTINE
OTU-MAP
N=S3, LOAD RESET ;SETUP FOR 2 WAY JUMP.
jTEST RUNG DECISION.
S14=RAM, JUMP2 FETCH
ZERO READ ;READ THE OUTPUT IMAGE
;EROM RAM INTO S14.
;IF RUNG IS FALSE, GET
;NEXT INSTRUCTION
;ELSE TURN THE OUTPUT
;OFF BY JUMPING TO RESET
;IN THE OTE MICRO-;ROUTINE.
_ _ TIMER/COUNTER INSTRUCTIONS
;COUNTER EQUATES AND MASKS.
CU = 08000 ;COUNTER UP ENABLED BIT OF
;COUNTER CONTROL WORD.
CD = 04000 ;COUNTER DOWN ENABLED BIT OF
;COUNTER CONTROL WORD.
OF = 01000 ;OVERFLOW BIT OF COUNTER
;CONTROL WORD.
UF = 0800 ;UNDERFLOW BIT OF COUNTER
;CONTROL WORD.
DN = S2000 ;COUNTER DONE BIT OF COUNTER
;CONTROL WORD.
NOTDN = ODFFF ;MASK TO RESET DN BIT.
OFUF = 01800 ;MASK FOR OVERFLOW AND
;UNDERFLOW BITS
CTU _ INC = 00001 ;COUNTER UP INCREMENT.
CTD INC = OFFFF ;COUNTER DOWN INCREMENT.
RES = CNTRL = OClFF ;MASK TO RESET THE DN, OV, UF, ;EN, ZR COUNTER CONTROL BITS.

;COUNTER UP ~CTU) ;TXIS INSTRUCTION INCREMENTS THE ADDRESSED LOCATION EACH TIME THE
;RUNG DECISION BECOMES TRUE. IT S~TS THE CONTROL BITS AS PRE-;VIOUSLY DESCRIBED. CTU _ MAP IS ENTERED DIRECTLY FROM THE
;CTU INSTRUCTION. CTU _ VECT IS ENTERED WHEN A CTU INSTRUCTION
;IS EXPANDED BY AN ADX.
;

;REGISTER USAGE:
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) ; S5-ACCUMULATED VALUE
; S6-PRESET VALUE (SAVED ON MACRO STACK) 1~7~S7~

; S7-ACCUMULATED VALUE (SAVED ON MACRO STACK) ; S8-STATE OF NCR.
; S9-ADDRESS IN CPU RAM OF THE BASE ADDRESS OF
COUNTER AREA IN MAIN MEMORY.
; S10=-1 FOR COUNTER UP, O FOR COUNTER DOWN.
; S12-MISCELLANEOUS SCRATCH.
; S15,S14-ADDRESS OF COUNTER STRUCTURE
; Q-SCRATC~
;

CTU _ MAP
S10=HIGH, JUMP LCNTR _ CMN ;FLAG AS COUNTER UP.
;GO TO COMMON STUFF.

;COUNTER DOWN (CTD) ;THIS INSTRUCTION DECREMENTS THE ADDRESSED LOCATION EAC~ TIME THE
;RUNG DECISION BECOMES TRUE. IT SETS THE CONTROL BITS AS PRE-;VIOUSLY DESCRIBED. CTD _ MAP IS ENTERED DIRECTLY EROM THE CTD
;INSTRUCTION. CTD _ VECT IS ENTERED WHEN A CTD INSTRUCTION IS
;EXPANDED BY AN ADX.
;

;REGISTER USAGE:
; S3-RUNG DECISION (O=FALSE, FFFF=TRUE) ; S5-ACCWIULATED VALUE
; S6-PRESET VALUE (SAVED ON MACRO STACK) ; S7-ACCUMULATED VALUE (SAVED ON MACRO STACK) ; S8-STATE OF MCR, ; S9-ADDRESS IN CPU RAM OF THE BASE A~DRESS OF THE
COUNTER SECTION OE MAIN MEMORY.
; S10=-1 IF COUNTER UP, O IF COUNTER DOWN.
; S12-MISCELLANEOUS SCRATCH.
; S15,S14-ADDRESS OF COUNTER STRUCTURE.
; Q-SCRATCH
CTD _ MAP
S10=0, JUMP LCNTR _ CMN ;ELAG AS COUNTER DOWN.
;GO DO COMMON STUFF.

;CTUCODE SUBROUTINE
;THIS SUBROUTINE HANDLES THE COUNTER UP (CTU) ~NSTRUCTION.
;

;REGISTER USAGE:
; S3=RUNG DECISION
; S5=T/C ELAGS
; S6=PRESET VALUE
; S8=STATE OF MCR.
; S9=INCREMENT (1) EOR COUNTER UP.
; S7=ACCUMULATED VALUE
; S10=BIT LOCATION OF OF.
; S12=BIT LOCATION OF UF.
; Q=MASK FOR COUNT UP (CU).
;

CTUCODE
Q=#CU ;Q=BIT LOCATION OF CU
S9=#CTU _ INC

70_ 1~ 7~

S10=OF ;S10=BIT LOCATION OF OF
S12=UF ;Sll=BIT LOCATION OF UF
N=S3 AND S8, JUMP COUNT _ COM
;CHECK RUNG DECISION.
;GO CONTINUE IN COMMON SECTION
&S2 ;

;CTDCODE SUBROUTINE
;THIS SUBROUTINE HANDLES THE COUNTER DOWN (CTD) INSTRUCTION.
;

;REGISTER USAGE:
; S3=RUNG DECISION
; S5=T/C FLAGS
; S6=PRESET VALUE
; S7=ACCUMULATED VALUE
; S8=STATE OF MCR, ; S9=INCREMENT (-1) FOR COUNTER DOWN.
; S10=BIT LOCATION OF UF, ; S12=BIT LOCATION OF OF.
; Q=MASK FOR COUNT DOWN (CD).
;

CTDCODE
Q=#CD ;Q=BIT LOCATION OF CD
S10=#UF ;S10=BIT LOCATION OF UF
S12=#OF ;S12=BIT LOCATION OF OF
S9=#CTD _ INC ;S9=INCREMENT FOR CTD.
N=S3 AND S8, JUMP COUNT _ COM
;CHECK RUNG DECISION.
;GO CONTINUE IN COMMON SECTION.
;COUNT _ COM SUBROUTINE.
;THIS SUBROUTINE HANDLES THE COUNTER UP AND COUNTER DOWN
;INSTRUCTIONS BASED ON PARAMETERS PASSED TO IT IN REGISTERS
;S9,SlO,S12, AND Q.
;

;REGISTER USAGE:
; S5=T/C FLAGS
; S6=PRESET VALUE
; S7=ACCUMULATED VALUE
; S9=INCREMENT FOR COUNTER.
; S10=BIT LOCATION OF OVERFLOW~UNDERFLOW BIT
; S12=BIT LOCATION OF UNDERFLOW/OVERFLOW BIT
; Q=BIT LOCATION OF OF/UF BIT
;

COUNT _ COM
N=S5 AND Q, JUMP RUNGOFF ZERO ;CHECK EIRST TIME RUNG
;IS TRUE.
;IF RUNG FALSE, JUMP.
N=S7~S9, JUMP ENER NZERO ;CHECK COUNTER
;OVERFLOW/UNDERFLOW.
;IF NOT lST TIME, DON'T
;INC./DEC. ACCUM. VALUE.

~l~S~i'75 S7=S7+S9, JUMP OVERUNDER OVER ;UPDATE ACCUM. VALUE.
;IF OVERFLOW/UNDERFLOW, JUMP
ENER
N=S5 AND ~OFUF ;PREVIOUS OVERFLOW OR
;UNDERFLOW?
CALL DOCMP ZERO ;IF NOT, TEST ACCUM. AGAINST
;PRESET IN DOCMP SUBROUTINE.
S5=S5 OR Q, RET ;SET CU/CD 8IT
OVERUNDER
N=S5 AND S12 ;PREVIOUS UNDERFLOW/OVERFLOW?
JUMP NOTUNOV ZERO ;NO, SET OE/UF BIT.
S5=NOT S12 AND S5, CALL DOCMP ;RESET UF/OF BIT
;TEST ACCUM. AGAINST
;PRESET IN DOCMP SUBROUTINE.
XIT
S5=S5 OR Q, RET ;SET CU/CD BIT
NOTUNOV
S5=S5 OR S10, JUMP XIT ;SET OF/UF BIT
RUNGOFF
N-S5 AND #OFUF ;PREVIOUS OVERFLOW OR UNDERFLOW?
Q=NOT Q, CALL DOCMP ZERO ;IF NOT, TEST ACCUM.
;AGAINST PRESET IN DOCMP
;SUBROUTINE.
S5-S5 AND Q, RET ;RESET CU/CD
;DOCMP SUBROUTINE
;THIS SUBROUTINE COMPARES THE ACCUMULATED VALUE WITH THE PRESET
;VALUE. IT SETS OR RESETS THE DN BIT.
,REGISTER USAGE:
; S5=T/C FLAGS
; S6=PRESET VALUE
; S7=ACCUMULATED VALUE
; S12=SCRATCH
;

DOCMP
S12=#DN ;SETUP S12 WITH MASK.
N=S6 XOR S7 ;CHECK SIGN BITS.
N=S7-S6, JUMP DIFFSIGN MINUS ;COMPARE ACC. TO PRESET.
;IF NUMBERS ARE OF
;DIFFERENT SIGN, GO
;HANDLE.
RESDN
S5=NOT S12 AND S5, RET NCARR ;IF NO CARRY ACCUM. PRESET.
;RESET DN BIT AND RETURN.
SETDN
S5=S5 OR S12, RET ;OTHERWISE SET DN.
DIEFSIGN
N-S7, LOAD RESDN ;IF ACCUMULATED IS POSITIVE, ;SET THE DN BIT. OTHERWISE
;RESET IT.

117S~75 N=O, JUMP2 SETDN PLUS ;INSURE NCARR CONDITION SO
;ROUTINE WILL RETURN AT RESDN.
DOCMP
S12=#DN ;SETUP S12 WITH MASK.
N=S6 XOR S7 ;CHECK SIGN BITS.
N=S7-S6, JUMP DIFFSIGN MINUS ;COMPARE ACC, TO PRESET.
;IF NUMBERS ARE OF
;DIFFERENT SIGN, GO
;HANDLE.
RESND
S5=NOT Sl2 AND SS, RET NCARR ;IF NO CARRY ACCUM. PRESET.
;RESET DN BIT AND RETURN.
SETDN
S5=S5 OR Sl2, RET ;OTHERWISE SET DN.
DIFFSIGN
N=S7, LOAD RESDN ;IF ACCUMULATED IS POSITIVE, ;SET THE DN BIT. OTHERWISE
;RESET IT.
N=O, JUMP2 SETDN PLUS ;INSURE NCARR CONDITION SO
;ROUTINE WILL RETURN AT RESDN.
_ 1175~75 Arithmetic and Logical Instruction ,LOGICAL INSTRUCTIONS
;WORD AND ("AND" WORD AT SOUROE 1 WITH WORD AT SOUROE 2) AND MAP
Q-#NC SSD
CALL WORDSTART
S10~S10 AND S7 S9-S9 AND S6, JUMP CWORDFINIS~ LATCH

;FILE AND
ANDF MAP
Q-$NC SSD
CALL FILESTART
AND NEXT

S9=S9 AND S6, CALL CFILEFINISH LATCH
JUMP AND NEXT

;WORD OR ("OR" WORD AT SOURCE 1 WITH WORD AT SO~RCE 2) OR MAP
Q-#NC SSD
CALL WORDSTART
S10=S10 OR S7 S9~S9 OR S6, JUMP CWORDFINISH LATCH

;FILE OR
ORF MAP
Q-#NC SSD
CALL FILESTART
OR NEXT
S10~S10 OR S7 S9~S9 OR S6, CALL CFILEFINISH LATCH
JUMP OR NEXT

;WORD MOVE (MOVE WORD FROM SOUROE TO DESTINATION) MOV MAP
Q=#NC SD
CALL WORDSTART
S9=S9, JUMP CWORDFINISH LATCH

;FILE MOVE
MOVE MAP
Q=#NC SD
CALL FILESTART
MOV_NEXT
S9=S9, CALL CFILEFINISH LATCH
JUMP MOV NEXT
_ ~75~t75 ;LIMIT TEST
LIM SI MAP
Q-#SI SSD
CALL WORDSTART
N'S6-S9-1 J~MP SETFLSE CARRY

S7-S10, CALL ADDRESSIT
CALL LOADIT

N~S7-S10-C
S3=~IG~, JUMP STOP NCARR
S3-LOW, JUMP STOP
SETFLSE
S35LOW, JUMP STOP

,WORD & FILE ARIT~METIC INSTRUCTIONS
;ARIT~METIC ADDITION
;

;WORD ADD SIGNED IN`TE OE R
ADD SI MAP
Q~#SI SSD
CALL WORDSTART
CALL ADD SI
JUMP WORDFINISH

;WORD ADD FLOATING POINT
ADD FP MAP
Q~#FP SSD
CALL WORDSTART
CALL ADD FP
J~MP WORDFTNIS~

;FILE ADD SIGNED INTEGER
ADDF S~ M~P
Q-#SI SSD
CA~T FILESTART
ADD NEXT
CALL ADD SI
CAIL FILEFINIS~
JUMP ADD NEXT

~ 175575 ,ARITHMETIC SUBTRACTION
;WORD S~BTRACT SIGNED INTEGER
SUB_SI MAP
Q=#SI SSD
CALL WORDSTART
CALL SUB SI
JUMP WORDFINISH
_ ,ARITHMETIC MULTIPLICATION
;WORD NULTIPLY SIGNED INTE OE R
MUL SI MAP
Q=$SI SSD
CALL WORDSTART
CALL MUL SI
JUMP WO~DFINISH

,ARITHMETIC DIVISION
;WORD DIVIDE SIG~ED INTE OE R
DIV SI MAP
Q=#SI SSD
CALL WORDSTART
CALL DIV SI
JUMP WORDFINISH

;WORD DIVTDE FLOATING POINT

;FILE DIVIDE FLOATING POINT
DIVE S I MAP
-- -- QS#s I SSD
CALL FILESTART
DI~ NEXT
C~LL DI~ SI
CALL FILEFINISH
JUMP DI~ NEXT
_ ,ARITHMETIC SQUARE ROOT
;WORD SQUARE ROOT SIGNED INTEGER
;SQR SI MAP
Q=~SI_ SD
CALL WORDST~RT
CALL SQR SI
JUMP WORDFINISH

~7~575 ;FILE SQUARE ROOT S I~NED INTE OE R
;SQRF SI MAP
Q-#SI SD
CALL FILESTART
SQR NEXT
CALL SQR SI
CALL FILEFINISH
JUMP SQR NEXT
._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Routines EmPloved bv Arithmetic & Loqic Instructions ;WORD START
;ROUTINE TO HANDLE rHE SETUP FOR WORD INSTRUCTIONS, ALSO
TESTS RUNG DECISION
;IF THE RUNG IS FALSE THE INSTRUCTION IS EXITED, IF TRUE, NEXT SO IS COMPUTED
;ONE OR TWO SOURCES ARE ADDRESSED, DATA IS LOADED AND A
RETURN IS EXEC~TED.
WORD START

JMPOP DUMP PIPE ZERO ;JUMP IF R~NG IS FALSE
CALL NEXT S0 ;GET NEXT S0 SAVE S13 ADDR N-#WORDRWCTRL WRITE ;NEXT VAL OE O~ PC
DATA Sll-Q
N~Sll AND #SD WRITE ;READ WRITE CONTROL
JUMP ONEWSRC NZERO ;JUMP IF ONE SOUROE
TWOWSRC
CALL SAVE67 ;SAVE REGISTERS 6 AND 7 CALL ADDRESSIT ;SET ADDRESS
CALL LOAD ;LOAD DATA
S6-S9 ;SAVE DATA

ONEWSRC
CALL ADDRESSIT ;SET ADDRESS
JUMP LOAD ;LOAD DATA
;RETURN IS DONE FROM LOAD
_ ;~OUTINE TO HANDLE WORD INSTRUCTIONS FINISHING, GOES DIRECTLY
TO FETC~
;SAVES T~E DATA, ADDRESSES THE DESTINATION, READS THE DATA
BACR FROM RAN, ;STORES THE DATA AT THE PROPER MAIN MEMORY ADDRESS, RESTORES
REGISTERS Ç ~ 7 ;IF NECESSARY, THEN JUMPS TO FETCH.
WORDFINISH
ADDR N=S13-#5 DATA N=S10 ADDR N=S13-#6 WRITE ;DATA HIGH
DATA N=S9 CALL ADDRESSIT WRITE ;DATA LOW
CALL REFRAM
CALL STOREIT ;WRITE DATA

~75575 ADDR N~WORDRWCTRL
N~RAN AND #SD READ ;READ-WRITE CONTROL
WORD
CALL RESTR67 ZERO ;CALL IF 6&7 SAVED
JMPOP FETCH ;GO TO NEXT INSTRUCTION
_ ;THIS ROUTINE ~Q-ADS DATA WHO'S ADDRESS IS POINTED TO BY THE
; REGISTER POINTER'S CURRENT DATA BLOCX A~DDRESS
; N-l DATA TABLE SECTION
; N-2 INCREMENT VALUE
; N-3 ADDRESS HIGH
; N-4 ADDRESS LOW
; N-5 DATA HIGH
; N-6 DATA LOW
LOAD
ADDR N-S13-#4 BACXL S14~RAM READ ;ADDRESS LOW
ADDR N-S13-#3 BAC~H S15-RAN READ ;ADDRESS HIGH
LOAD COM
J~MP LOADFROMCPU PLUS
ADDR N-S13-#1 BRU ;DATA
S9-DATA, HOLD
S2=RAM-#6 READ DA ;SECTION N~MBER
S10-LOW, JUMP NOT6L NZERO HOLD ;JUMP IF NOT SECT 6 BAC~L N=S14+1 HOLD
BACg~ N=S15+C HOLD
CONT BACXR DA;DATA 2ND WORD
S10~DATA, CALL INTER IVECT DA
S~IPIT
ADDR N=#WO~DRWCTRL 8ACXR ;DUMMY READ
NzRAM AND #SICOWV Æ AD ;RWCONTROL
CALL CONVERTFR N ZERQ ;CONVERT IF NECESSARY
SRIP CONVE~
ADDR N=S13-#5 DATA S10=S10 ADDR N=S13-#6 WRITE ;DATA ~IG~
DATA S9=S9 RET WRITE ;DATA LOW
S LOAD
BACKL S14=S9 BAC~H S15=S10, JUMP LOAD COM
LOADFROMCPU
ADDR S9zS14 DATA S9SRAM READ ;DATA LOW
S10~LOW, JUMP SKIP CONVER ;DATA HIGH = O

N=S2-#6 JUMP SKIPIT NZERO ;JUMP IF NOT SECT12 ~7~S75 ADDRN-#WORDRWCTRL
N-RA~ AND #CONV READ ;READ WRITE CONTROL
JUMP SRIPIT NZERO
ADDRN=$POIN$ERFLG
S2= -RAM READ ;POINTER FLAG
S2=S2+1, JUMP LSECTION ZERO
JUMP LFILE ZERO
BACRL N=S14+1 8ACR~ N-S15+C
S10=LOW BACRR DA;2ND DATA WORD
S9-DATA AND #WORDMASR DA
RET
LSECTION
LL9=BFLOP
LL9=S9 LL9=S9 S9=S9 AND #SECTIONMASK
RET
LFILE
S9=S9 AND #FILEMASK
RET
_ STOREIT
ADDR N=~WORDRWCTRL
N=R~M AND #S$CONV READ ;RWCONTROL
CALL CONVERTTO NZERO
STORENC
ADDR NSS13-#4 BACRL S14-RAM READ ;ADDRESS LOW
ADDR N=S13-#3 BACR~ S15zRAM R~AD ;ADDRESS HIGH
STOREA
BACRD N=S9, JUMP STOREINCPU PLUS ;DATA LOW
ADDR N-S13-#1 S2=R~M-#6 READ ;SECTION #
JUMP NOTS6 NZERO ;JUMP IF NOT SECTION 6 CONT BWH
BACX~ N=S14+1 HOLD
BAC~X N=SlS+C HOLD
BACXD N=S10 HOLD jDATA 2ND WORD
RET BACXW ;DATA 2ND WORD
S-STORE
BACKL S14=S9 BACXH S15=S10, CALL REFRAM
S15=S15, JUMP STOREA
STOREINCPU
ADDR N=S14 DATA N=Sg ADDR N=#SlFOFLG WRITE ;DATA TO CPU RAM
NOTIFY
S14=RAM READ ;TEST FOR OUTPUT IMAGE
TABLE
RL2=S14, RET ZERO ;RETURN IF IN INPUT TABLE
;NOTIFICATION OF SCANNER
;ROUTINE FOR THIS
RACK/SLOT

~75S75 S2=S2 AND #0LFE
ADDR S2-S2+#0200 ;INDEX INTO SCANNER MAP
S5=RAN READ ;SCANNER ADDRESS HIG~
ADDR N=S2+1, RET ZERO ;RETURN IF NO SCANNER
S14-S14 AND #07 BACRL N=RAM~S14 READ ;SCANNER ADDRESS LOW
BACgH N=S5+C
RET 8ACKW ;NOTIFY SCANNER

N=S2-#6 ADDR N=#SlFOFLG
~UMP NOTIFY BACKW ;DATA, WRITE IF NOT

;NOTIFY SCANNER IF IN
OUTPUT IMA OE

ADDR N-#WORDRWCTRL
N RAN AND #CONV READ ;RW CONTROL

RET BACKW ;NO SPECIAL CASE WRITE
DATA

ADDR N=~POINTERFLG
S2--RAM READ ;POINT~R FLAG
S2=S2+1, J~NP SECTION ZERO BR8 ;READ DATA IN SECTION

;JUMP IF MODIFY OF
SECTION #
JUMP FILE ZE~O HOLD ;JUMP IF MODIFY OF
FILE~
WORD
BACKL N=S14+1 BACR~ ~-S15+C
S9=S9 AND #WORDMASR BRH DA;SECOND WORD
;MARE SURE WORD # FITS
S2-DATA AND #NWORDMASK DA ;MASK OFF WORD
BACRD N=S2 OR S9 RET BACKW ;NEW WORD POINTER
FILE
S9=S9 AND #FILEMASK HOLD ;MAKE SURE IT FITS
S2=DATA AND #NFILEMASK HOLD ;MASX OFF FILE #
BACKD N=S2 OR S9 HOLD ;PUT IN FILE #
RET BACKW ;NEW FILE POINTER
SEI::TION
S2=DATA HOLD
LL9=BFLOP HOLD ;PUT SECTION # INTO MSBS
LL9=S9 HOLD

LL9=S9 HOLD
S9=S9 AND #SECTIONMASK HOLD ;MARE SURE IT FITS
S2-S2 AND #NSECTIONMASK
HOLD ;MASR OFF SECTION #
BACKD N=S2 OR S9 HOLD ;PUT IN SECTION #
RET BACXW ;NEW SECTION POINTER
_ ~7~;5~5 ;ENTRANOE POINT FOR CONVERSION FROM T~E DATA TABLE TYPE
CONVERTER
ADDR N-S13-#1 N=RAM . READ

;ENTR~N OE POINT FOR CONVERSION TO THE DAT~ TABLE TYPE
CONVERTTO
ADDR N-S13-#1 N=RAM READ

&A16 TYPESFR
RET ;SECTION 0 RET ;SECTION 1 RET ;SECTION 2 JUMP BIN SI ;SECTION 3 JUMP SI16 SI32 ;SECTION 4 JUMP SI16 SI32 ;SECTION S
JUMP FLOAT SI ;SECTION 6 J~MP BCD sr ;SECTION 7 JUMP 8IN-SI ;SECTION 8 JUMP BIN-SI ;SECTION 9 JUMP BIN SI ;SECTION 10 RET ;SECTION 11 JUMP BIN SI ;SECTION 12 RET ;SECTION 13 RET ;SECTION 14 R~T :SECTION 15 TYPESTO
RET ;SECTION 0 RET ;SECTION 1 RET ;SECTION 2 JUMP SI BIN ;SECTION 3 JUMP SI~2 SI16 ;SECTION 4 JUMP SI32 SI16 ;SECTION 5 JUMP SI FLOAT ;SECTION 6 JUMP SI BCD ;SECTION 7 JUMP SI BIN ;SECTION 8 JUMP SI BIN ;SECTION 9 JUMP SI BIN ;SECTION 10 RET ;SECTION 11 JUMP SI BIN ;SECTION 12 RET ;SECTION 13 RET ;SECTION 14 RET ;SECTION 15 _ ;ROUTINES FOR CONVERSION TO AND FROM DOUBLE PRECISION SIGNED
I~TE OE R

S9=S9 S10=LOW, RET PLUS
S10=HIGH, RET

S132 SIl~
S10=S10 N=S10 + 1, JUMP PSI32JMP ZERO
S9=S9, JUMP MSI32JMP ZERO
JUMP CONV ABORT

1175~75 N=S9 RET PLUS
J~Mæ CONV ABOR$

RET MINUS
JUMP CONV ABQRT
_. _ _ _ ;<<CONVERT BCD TO SIGNED INTEGER (RANGE O TO 999g)>>
PCD SI
Q-S9 ;SAVE DATA
S9zLOW ;CLEAR WORKING REGISTERS
S10=LOW, LOAD 3 RCDA SI
LL9Q-S9, AGAIN BCDA SI ;GET MSD INTO Sg RCD8 SI ;S9 HOLDS RUNNING
ANSWER
PUSH 2 ;3 MORE ~IGITS TO DO
S10-LOW ;RESET S10 LLlOQ-S10 ;GET NEXT 4 BITS IN S10 LLlOQ=S10 LLlOQ~S10 LLlOQ=S10 S9=69+S9 ;MULTIPLY PREVIOUS
RUNNING
S14~S9 ; ANSWER BY 10 S14-S14+S14 S14=S14+S14 ;S14 HOLD 8 TIMES
PREVIOUS
S9=S14+S9 ;S9 HOLDS TWICE PREVIOUS
S9=S9+S10, BACR ;PREVIOUS X10 PLUS NEXT
DIGIT
GOBACK
S10=LOW RET ;DONE RETURNS POSITIVE
VALUE
;<~CONVERT SIGNED INTEGER TO 8CD (RAN OE O TO 9999)>>
SI BCD
S14=S9 ;COPY SIGNED INTEGER

Q=LOW, JUMP BCD ABORT MINUS ;JUMP IF TOO BIG/SMALL
N=S14-#10000 ;TEST FOR GREATER

S9=lOW, JUMP BCD A30RT P.LUS ;CLEAR S9HOLDS RESULTANT
S5=#4 ;SET DIGIT COUNTET TO 4 S15=~1000 ;INITIALIZE TO THOUSANDS
SI BCDA PLACE
S14=S14-S15 ;DETERMINE DIGIT IN
THIS PLACE
S9-S9+1 JUMP SI BCDA PLUS ;REPEAT TILL DONE
S14=S14+S15, LOAD 3 ;ADJUST FOR EXTRA
SUBTRACT
S9=S9-#1 S5=S5-#1 ;DECREMENT & TEST COUNT
SlOzLOW, RET ZERO ; FOR DONE
ROTRES
LL9Q=S9, AGAIN ROTRES ;SHIFT RESULT LEFT 4 1~75S75 N=S5-$1 S15=Q+1, J~JMP SI BCDA ZE~O ;JI~ IF l'S DIGIT NEXT
S15--#10 ;SET TO 10 'S DIGIT
N--S 5- ~ 2 Q--LOW, JUMP SI BCDA ZE~O ;JIJMP IF 10'S DIGIT NEXT
S15=$100 ;SET TO 100 'S DIGIT
Q=LOW, Jl~MP SI BCDA ;31JMP 100 'S DIGIT NEXT
BCD ABORT
N=S10 JUMP SM ABORT MINUS
Jl~MP BIG ABORT
_ ~ ~75575 APPENDIX C
Micropro~rams for Filest~rt and Filefinish Routines FILESTA~T
CALL NEXT SO ;GET
ADDR N=#FIRSTTIME ;TEST FOR PRESCAN
N=RAN READ ;FIRSTTIME
JUMP STOP NZERO ;STOP IF IN PRESCAN
ADDR N=#WORDRMCTRL
DATA N=Q
ILOAD S0=S0+1 WRITE ;REA~WRITE CONTROL
Q=LOW, CALL INTER IVECT ;GET FILE CONTROL WORD
N=INSTR AND #04000 S9=INSTR, JUMP ONELONG ZERO ;JUMP IF FILE CONTROL

TWOLONG ;WORD
ILOAD so=sa+l ;LOAD 2ND WORD OF FILE
CALL INTER IVECT ;CONTROL
S15-INSTR AND ~07FFF ;COUNTER # INTO S15 S14-S9 and #03FFF ;RATE/MODE INTO S14 JUMP HAVE EM
ONELONG
S15=S9 AND #03FF ;COUNTER #
RL9=BFLOP
RL14Q-S9 AND #OOlE ;MOVE RATE/MODE TO LSBITS
HAVE E~ ;COMPUTE COUNTER ADDRESS
;ON ENTRY SlS COUNTER#
CALL S COMP CTR ADR ; S14-RATE
BAC~L N-S2+1 BACKH ~aS5+C
CONT BAC~R DA;READ PRESET VALUE
Q-DATA, CALL INTER I~ECT DA
BACKL N-S2+#2 BAC~H N-S5+C
CONT BACXR DA;READ ACCU~ULATED V~LUE
Q=Q-DATA, CALL INTER IVECT DA;CALC~LATE WORDS
REMAINING
BACKL S2-S2 ;IN FILE
BACRX S5=S5 N=S9 AND #08000 BACKR DA;READ CONTROL WORD
S15-DATA, JUMP TOBEORNOT NZERO
DA ;JUMP IF DISTRIBUTED
;MODE
SPECIAL
514=~S14 S14=S14+1 S14=S14+1, JUMP INST_ABORT PLUS;JUMæ IF MODE NOT ALLOWED
S14=S14+1, JUMP COMPLETE ZERO ;JUMP IF COMPLETE MODE
S14=S14+1, JUMP NOINCREMENT ZERO
;JUMP IF "NONE" MODE
INCREMENTAL ;OT~ERWISE INCREMENTAL
N=S15 AND #FILEDONEBIT ;MODE
N=S3 and S8, JUMP DBSET
NZERO ;JUMP IF DONE BIT SET

1~L75~75 DATA S14-S14+1 JUNP INCT NZERO ;SET RATE - 1 ;JUMP IF ~UNG TRUE
INCF ;RUNG FALSE
BACKD N=S15 AND $RES_EN
JUMP STOP BACXW ;RESET ENABLED 3IT
INCT ;RUNG TRUE
N=S15 AND #FILEENABIT
JUMP STOP NZERO ;JUNP IF ENABLED
ADDR NSS13-#3 JUMP SETENABIT WRITE;RATE
;SET ENABLE AND DO IT
COMPLETE
S14=Q, JUMP RATELTTODO ;RATE = TODO FOR COMPLETE
;JUMP
NONINCREMENT
ADDR N=$WORDRWCTRL
DATA N-RAM OR #NOINCBIT READ ;RW CONTROL
N~S3 and S8, LOAD SETENABIT
S14=S14+1, JUMP2 STOP ZERO
WRITE ;RW CONTROL, NO INC
BIT SET
;SET RATE - 1 ;J~MP IF RUNG FALSE
;OTHERWISE JUMP TO
TOBEORNOT ;SETUPDONE
N=Q-S14 JUMP RATFLTTO~O PLUS;IF TODO RATE<THEN
S14=Q ;SET R~TE-TODO
RATELTTODO
DATA S14=S14 ADDR N=S13-$3 N=SlS AND #FILEDONEBIT WRITE ;PUSH RATE
N~S3 AND S8, JUMP DBSET NZE~O;JUMP IF DONE BIT SET
JUMP SETENABIT NZERO;JUMP IF RUNG TRUE
N=S15 AND #FILEEN~BIT
JUMP SETUPDONE NZERO;JUMP IF ALREADY STARTED
JUMP STOP ;DONT DO ANY THING
DBSET ;DONE BIT SET
JUMP DBSETT NZERO ;JUMP IF RUNG TRUE
DBSETF
BACXD N=S15 AND #RES_DN_FD EN
CONT BACXW ;RESET DONE AND ENABLE
BITS
BACXL N=S2+#2 BACK~ N=S5+C
BACXD N=LOW ;CLEAR ACCUMULATED
JUMP STOP BACXW ;JUMP
DBSETT ;DONE BIT SET, RUNG TR OE
N=S15 AND #FILEENABIT
BACXD N=LOW, JUMP STOP NZERO ;STOP IF ENABLE BIT SET
BACKT. N=S2+#2 ;CONTINUE IF NOT SET
BACKH N=S5+C
CONT BACKW ;RESET COUNTER AC-CUMULATED
BACKH N=S5 BACKL N=S2 ~'7~'75 N-S15 AND #RES DN EN ;RESET DONE BIT
SETENABIT
BACRD S15=S15 OR #FILEENABIT ;SET FILE ENABLE BIT
CONT 3ACXW ;FILE CONTROL WORD
SETUPDONE
CALL INTER I~ECT
N=S14 JUMP STOP ZERO
S13=S13-#3 ADDR N=#WORDRWCTRL
N=RAM AND #S OR SD READ ;READWRITE CONTROL FLAGS
J~MP ONESRC NZERO
TWOSRC
CALL SAVE67 ;SAVE S6 and S7 CALL ADDRESSIT ;SET UP ADDRESS
CALL MODIFY ;CHANGE IF NE OESSARY
CALL LOAD ;LOAD SOURCE DATA
S6=S9 ;SAVE DATA
S7=Sl0 Sl3=Sl3-#6 ;C~ANGE STACX POINTER
ONESRC
CALL ADDRESSIT ;SET UP ADDRESS
CAL~ MODIFY ;CHANGE IF NECESSARY
ADDR N=#WORDRWCTRL
N=RAM AND #SS R~AD ;READWRITE CONTROL WORD

N-RAM AND #S READ
J~MP READYORNOT NZERO
S13=S13-#6 DESTINATION
CALL ADDRESSIT ;SET UP ADDRESS
CALL MODIFY ;CHAN OE IF NECESSARY
S13=S13+#6 CALL LOADIT ;LOAD SOUROE DATA
READYORNOT
Sl3=S13-$6 Q=Q
RET
_ ;T~IS ROUTINE HANDLES THE FINISHING OF A FILE INSTRUCTION AND
;THE DECISION TO JUMP TO FETCH OR TO RETURN TO COMPLETE
;ANOTHER PASS THROUGH THE INSTRUCTION
FILEFINISH
CALL STOREIT
ADDR N=#WORDRWCTRL
N=RAM AND #NOINCBIT READ ;RW CONTROL WORD
JUMP STOP NZERO
a FDONE
ADDR S13=#OLDS13 ;SET UP S13 POINTER
S13=RAM READ ;OLD VALUE OF â 13 ADDR N=S13-#1 Sl5aRAM READ ;COUNTER ADDRESS HIGH
ADDR N=S13-#2 BACXL S14=RAM+l READ ;COUNTER ADDRESS LOW
BACXH S15=S15+C
CONT BACXR DA;READ COUNTER PRESET

~175575 DA
BACXL S14~S14+1 BACRH S 15-S15+C
CONT BACRR DA;READ COUNTER AC-CUMULATED
BACRD S5=DATA+1 DA ;INCREMENT ACC~MULATED
N-S5-S2 BACKW ;UPDATED COUNTER ACCUM.
J~MP SETDONEBIT CARRY
DA ;JUMP IF PRE = ACU
ADDR S 13=S13- #3 DATA N=RAM_#1 READ ;DECREMENT RATE COUNT
JUMP STOP ZERO WRITE ;JUMP IF DONE
CALL REFRESHIT ;REFRESH S1 ADDR N-#WORDRWCTRL
N=R~N AND $SD READ ;READ WRITE CONTROL
JUMP REFRDEST NZERO
S13_S13_$6 56~S9 S7=S10, CALL REFRESHIT ;REFRESH S2 REF~DEST
S13-S13-#6 ;REFRESH DESTINATION
ADDR
ADDR N-S13-#2 S9=RAM READ ;INCREMENT VALUE
JUMP REFRDEST1 ZERO ;JUMP IF ADDR NOT
C~ANGING
CALL MOD ADDR1 ;MODIFY ADDRESS
REFRDESTl S13=S13+#6 ;POINT TO SOURCE 2 DATA
ADDR N-S13-#5 ;POINT TO HIG~ DATA
S10~RAM RE~D ;LOAD HIGH DATA
ADDR S13=S13-#6 ;POINT TO LOW DATA AND
;POINT S 13 TO DESTI-NATION
S9=RAM, RET READ ;LOAD LOW DATA, RETURN
SETDONEBIT
BACXL S14=S14-#2 BAC~H S 15-S15-#0-C
CONT BRH ;CONTROL WORD
BACXD ~-DATA OR #FILEDONEBIT ~OLD
JUMP STOP BACKW ;CONT~OL WORD

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A programmable controller which comprises:
a data table for storing data of different types in respective data table sections;
memory means for storing a control program which includes arithmetic instructions that operate on data in different data table sections; and a processor for sequentially reading the control program instructions from the memory and operating upon data stored in the data table, the processor including:
(a) means responsive to a source operand address associated with an arithmetic instruction read from the memory means, for reading data from an indicated data table section and converting it to a native data type;
(b) means responsive to the last named means and to an operation code associated with an arithmetic instruction read from the memory means, for performing the indicated arithmetic function on source data which has been converted to the native data type; and (c) means responsive to the last named means, and to a destination operand address associated with an arithmetic instruction read from the memory means, for converting the data which results from the arithmetic operation from the native data type to the data type of the data table section indicated by the destination operand address and for writing the converged data to the indicated data table section.

2. The programmable controller as recited in claim 1 which includes:
an image table for storing data of various data types which is input from sensing devices connected to the program-mable controller;
means coupled to the image table for inputting data from the sensing devices and storing it in the image table;
and in which the processor further includes:
(d) means responsive to a control program instruc-tion read from the memory means for reading addressed data from the image table and writing it to the data table section which stores its data type.

3. The programmable controller as recited in claim 2 in which the processor further includes:
(e) means responsive to a control program instruc-tion read from the memory means for reading addressed data from the data table and writing it to the image table.

4. In a programmable controller which inputs data of various types from sensing devices connected to it and performs operations on such data in response to instructions in a stored control program, the improvement therein compris-ing:
a data table having a plurality of sections, each of which stores data of a particular type;

means responsive to instructions in the control program for storing the input data from sensing devices in the data table section which stores the same data type;
means for executing instructions in the control program which includes means for converting source data read from a data table section to a native data type, means for performing opera-tions on the converted source data, and means for converting the data resulting from an operation to the data type of a destina-tion data table section.

5. The programmable controller as recited in claim 4 in which the operation performed is indicated by an operation code in the instruction being executed, the source data table section is selected by a source operand address in the instruction being executed, and the destination data table section is selected by a destination operand address in the instruction being executed.

6. The programmable controller as recited in claim 4 in which the means for storing input data in the data table includes:
an image table for storing input data at locations associ-ated with each of the sensing devices;
scanner means for continuously inputting data from the sensing devices and storing the data in the associated image table location; and means responsive to instructions in the control program for moving input data from selected locations in the image table to selected data table sections.

7. The programmable controller as recited in claim 4 in which operating devices connect to the programmable controller, and the programmable controller includes means responsive to instructions in the control program for outputting data from selected data table sections to operating devices which employ the same data type.

8. In a programmable controller having a processor which continuously and repeatedly scans and executes instructions in a stored control program to input data from sensing devices, per-form logical operations on such data, and output the data which results from such logical operations to operating devices, the improvement therein comprising:
means forming part of the processor for executing file instructions which form part of the control program and which require operation on data files comprised of a plurality of separately addressable data elements including:
(a) detector means for detecting the presence of a code in a file instruction read from the control program which indicates that the file operation is to be carried out in a distributed mode;
(b) rate means coupled to the detector means for detecting the presence of another code in the file instruction which indicates the number of file data elements to be operated upon during each scan through the control program;
(c) counter means for storing an indication of the file data elements which have been operated upon;
(d) operation means coupled to the counter means and the rate means for performing an operation on an indicated number of file data elements which have not been operated upon; and (e) means coupled to the counter means and the opera-tion means for detecting when all file data elements have been operated upon;
wherein operations on data files may be performed over a plurality of scans through the control program to thereby distribute their execution time.

9. In a programmable controller having a processor which reads instructions from a control program and executes them to examine the state of input devices and control the state of output devices, the improvement which comprises:
memory means connected to the processor for storing a data table having a plurality of sections, each section storing a specific data type;
wherein said processor includes means for addressing sections of said data table and means for reading data from and writing data to addressed sections of the data table and means for converting the data type read from one section into the data type of other sections such that processing of data in the data table is accomplished with automatic conversion of data types.

10. In a programmable controller which stores a control program comprised of a series of control instructions that direct a processor to examine the state of input devices and operate output devices, and in which the processor repeatedly and con-tinuously scans the control program to provide prompt responses to changes in the states of input devices, the improvement com-prising:
addressable storage means coupled to the processor for storing a data file comprised of a plurality of separately addressable lines; and means associated with said processor for executing a file control instruction in said control program that directs a func-tion to be performed on said data file, said executing means comprising:
(a) means for reading a rate number in said file control instruction;
(b) means for storing said rate number;
(c) means for performing the function indicated by said file control instruction during each scan through the control program on successive portions of said data file, and wherein the number of lines in each portion is deter-mined by the stored rate number.