US3622702A - Tape reader and control system - Google Patents

Abstract

A system providing for improved local and remote control over operation of a tape reader. The controls being operative to selectively initiate and automatically terminate both the reading and omission of data, with the omission operations being effected at a higher rate than the reading operations. These controls also being operative to automatically inhibit reading operations for various time intervals when the unit is supplying a teleprinter and particular mechanical commands are being executed by the teleprinter.

Description

United States Patent [72] Inventors John J. Larew;

Paul J. Moran, both of Waynesboro, Va. [21 Appl. No. 789,841 [22] Filed Jan. 8, 1969 [45} Patented Nov. 23, 1971 [73] Assignee General Electric Company [54] TAPE READER AND CONTROL SYSTEM 28 Claims, 12 Drawing Figs.

[52] 11.8. CI 178/17 R, 197/20 [51] lnt.C1 1-1041l7/l2 [50] Field of Search 178/17, 17 A, 17 B, 23, 23.1, 79, 80, 81, 17.5; 197/20; 3401174.] A, 174.1 K

[56] References Cited UNITED STATES PATENTS 3,414,103 12/1968 Knudsen et a1. 197/20 3,333,668 8/1967 Sausele 197/20 3,291,277 12/1966 Borrelli et a1. 197/20 3,280,256 10/1966 Clark et al. 178/179 3,219,165 11/1965 Greene et al. 197/20 RUN STOP STOP RAPID ADVANCE READER CONTROLS 2,905,299 9/ 1 959 Hildebrandt 197/20 2,905,298 9/1959 Blodgett et al 197/20 2,894,614 7/1959 Lambert et al. 197/20 2,865,487 12/1958 Hildebrandt 197/20 2,700,446 l/l955 Blodgett 197/20 3,417,202 12/1968 Kolpek 178/31 3,403,225 9/1968 Mislan et al. 179/2 3,353,744 11/1967 Becking et al. 197/20 Primary Examinerl(athleen H. Claffy Assistant Examiner-Tom DAmico Anorneys- Lawrence G, Norris, Michael Masnik, Frank L.

Neuhauser and Oscar B. Waddell TAPE READER TELEPRINTER ADVANCE AND READ GATES DATA GATES |-24 PUNCH DECODER SHORT DELAY COMPA R.

LONG DELAY COMPAR.

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JOHN J. LAREW .PAUL J. MORAN THEIR ATTORNEY PATENTEnuuv 23 Ian 3.622.702

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JOHN J. LAREW PAUL' J. MORAN THEIR ATTORNEY PATENTEUuuv 2a IHTI SHEET 7 [IF 7 INVENTOR. JOHN J. LAREW PAUL J. MORAN THEIR ATTORNEY @Ww NE? FEE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to readers for stored ,data; more particularly, it concerns a system that provides automatic control of a reader and permits both automatic and manual control of the storage medium editing functions.

The rapidly expanding field of communications relies more and more upon automatic data-handling equipment. Such equipment must be capable of accurate and extremely fast transmission and reception of data. By the elimination of manual operations, it has been found that not only speed but also reliability can be increased. Oftentimes, data-handling systems include the use of either magnetic or punched recording media. The recording medium is run through reading equipment in order to interpret its contents and control operation of suitable transmitting or utilization equipment.

2. Description of the Prior Art Both magnetic and punched tape recording systems utilize binary codes to record information. According to such usage, the presence or absence of a magnetic bit or a hole" is representative of a logic 1 or logic 0. A large number of code systems have been developed using discrete permutations of a particular number of bits to represent specific numeric, alphabetic, and command characters. The system adopted for a particular use depends upon the requirements peculiar to that use. It may also be stated that generally, the selection of magnetic or punched recording media is also dependent upon the peculiarities of each use. In many cases, the media are direct equivalents of one another.

At the present time, recorded data is used extensively in telecommunications, machine tool control, accounting, and computing. In addition, it is being used with increasing success in the office equipment field. Teleprinters and typewriters are now used to convert data from coded tapes to conventional language texts. n the other hand, data is sometimes transmitted in its original form to remote locations where it is simply reproduced.

The great advantages of high-speed operation have resulted in the development of equipment that responds to data much more rapidly than can be physically monitored by human operators. Thus, parity check techniques have been developed which permit automatic testing for errors and which also provide the means for initiating steps to remove these errors. Nevertheless, it is still necessary and desirable to provide means for the override of automatic operation by a human operator in order to effect editing operations that cannot be stored for automatic implementation.

Two presently used data-handling systems may be considered in order to appreciate the types of problems the subject invention is intended to solve.

The first system involves telecommunication wherein a tape controls the data presented to a teleprinter from a tape reader. The control tape may contain too much data, undesired repetitive data, or erroneous data. The presentation of such data to the teleprinter is undesirable. Accordingly, means must be provided for detecting its presence and selectively omitting it. Existing equipment in some instances offers this capability; however, undue complications and excessive time are involved in accomplishing the desired functions. The control tape may also contain original data that is to be replaced with new data. In this case, means must be provided for detecting the time of presentation of the original data and then efiecting its replacement. Here too, existing equipment offers highly unsatisfactory means for accomplishing the desired functions.

Similar problems occur in the ofi'rce equipment field wherein automatically operated typewriters are controlled by tapes developed during the typing of a draft. In this type of system, the final copy of a text is developed by permitting the tape to control the typewriter only when approved passages are being typed. When a portion of the original draft is to be modified, a human operator may override the tape control and manually insert new matter.

SUMMARY OF THE INVENTION The present invention contains a number of features of particular value in the systems mentioned above. Although the illustrative embodiment refers to the use of a particular type of punched tape, it will be apparent that otherrecording systems can be used, such as magnetic recording, or systems where signals representing characters are recorded in a given sequence along a line. For purposes of description, it has been assumed that thetape reader is associated with a teleprinter which is responding to the data that is read. Obviously, this specific combination of equipment is also not necessarily germane to the invention and other equipment may be used in conjunction with the novel elements of the tape reader system and controls.

Since the embodiment of the invention described hereinafter functions with a teleprinter, the ASCII code system has been adopted. It is contemplated that a punched tape having nine columnsis employed. Seven of these columns represent bits of a binary code; the eighth column is the parity check bit; and the ninth column contains sprocket holes. For purposes of simplicity, when reference is made to a character, it will beunderstood that this means a printable character such as an alpha-numeric symbol or nonprintable character such as line feed, which is represented by a particular pennutation of binary indications on the tape. A word" is an assembly of printable characters generally set off from the adjacent text by a nonprintable character such as the code SP" (space), or horizontal tab, carriage return or a printable character suchas a period. A ?line is a collection of printable characters set off at each end by a nonprintable character such as the code CR" (carriage return) or a printable character such as a period, etc. .It is important when responding to a tape reader, particularly with a teleprinter, that the tape reader provide adequate timing for thevarious mechanical functions that may be required by the teleprinter. For example, if the teleprinter is commanded to backspace, this is a mechanical operation that requires a. discrete time. In order to avoid forwarding characters to the teleprinter at a time when it cannot respond, the tape reader must accordingly be delayed for an appropriate interval. The same situation is true with respect to other commands such as carriage return and ribbon change.

An object of this invention is to provide an improved.arrangement for-reading and editing characters stored along a path in a recording medium.

An object of the invention is to provide an improved character reader (i.e., either printable or nonprintable) control systemv including means for detecting particular charactersprior to the forwarding thereof to subsequent equipment.

Another object of the invention is to provide an improved character readercontrol system including means for automatically initiating specific reader operations upon detection of particular characters.

It will be appreciated that some commands, such as line feed, carriage return, etc., require a longer period of time to execute thanl others. In view of this fact, it is desirable to provide variable delays in accordance with the particular command detected and furthermore, in accordance with the nature of the next character or characters. In the past, it has been the practice to follow commands such as line feed LP by a series of nonprintable characters on the tape in order to provide the necessary time delay. With'the present invention, the tape reader equipment automatically responds to detection of a line feed code and consequently, it is not necessaryto precode a tape to provide the necessary time delay.

Another object of the invention is to detect particular commands such as mechanical commands of line feed, etc., and effect delays in the transmission of subsequent printable characters until such commands can be responded to by the receiving equipment.

ll) IOIISO Yet another object of the invention is to provide for detection of commands and to provide variable delays in the transmission of subsequent data depending upon the nature of the subsequent data and the nature of the command itself.

It is also of value to be able to detect particular characters other than the aforementioned printer control characters and initiate special reader operation in response thereto. For example, a delete (DEL) character is presented on tape by activating all possible bits. This character is commonly used to erase an erroneously entered character or, in some cases, it is used to provide a time delay for operation of external equipment. It is advantageous to have the option of skipping such characters if desired. It may also be desired to skip whole paragraphs in certain texts. Thus, means foz'filetecting the commands for normal paragraph indentation and implementing such skipping are of value. Still further, any such skipping should preferably be carried out at a high rate of speed.

Another object of the invention is to provide an improved tape reader control system wherein the detection of certain characters will automatically initiate high speed operation of reader until detection of some other particular character or characters.

When a tape is being read in order to either generate a new tape or to transmit only selected information thereon, it is extremely important to be able to stop the printer on particular characters, words, or lines. This permits selective editing. Since normal high-speed reading precludes operator intervention, in effecting this type of editing, it is necessary to determine a target area for the editing by reading specific portions of the tape at a slow enough speed to ascertain their content. Subsequent to this determination, it becomes necessary to provide means for omitting the desired portions of the tape and/or for possibly inserting other matter in place thereof.

Another object of the present invention is to provide an improved character reader control system including means for slowing down the reader and selectively investigating either the next character, word, or line prior to forwarding this data to the connected equipment.

Another object of the invention is to provide an improved character reader control system having means for selectively and automatically omitting characters, words, or lines.

A further object of the invention is to effect omission of any desired portion of the data on the recording medium at a greater speed than the normal transmission rate.

Modern telecommunications provide means for requesting the receiving equipment to respond as to whether or not remote parity checking has established that the received data is accurate. Thus, the receiving equipment will send to the transmitting station either a NAK" (not acknowledged) or an ACK" (acknowledged) code if the received data does not satisfy parity requirements, or if it does satisfy parity requirements, respectively. In response to these acknowledgement signals, the transmitting station either repeats the preceding block of data, or proceeds with the transmission. At the remote location, the receiving unit records the acknowledgement signal on the tape that is being generated. Thus, where a block of data is transmitted which does not satisfy parity requirements, this block of data will appear on the recording tape followed by NAK." Where the block of data does satisfy parity requirements, it will be followed by ACK." During the reproduction of the tape, it is, of course, desirable not to reproduce the portions which are inaccurate as indicated by the NAK" symbol. In order to eliminate these portions, the tape may be run through the reader in a reverse direction and as soon as the NAK" symbol is discovered, the portion of the tape between it and the preceding ACK" symbol will be deleted.

It is an object of the present invention to provide means for recognizing NAK" characters and for subsequently running the reader at a high speed until an ACI(" character is detected.

Another important factor in the reading of tapes relates to what would appear to be a very simple matter. This concerns the detection of the end of the tape. In the past, this detection has been accomplished by mechanical means.

It is another object of the present invention to provide electronic means for detecting the end of tape and to thereafter automatically terminate operation of the equipment.

Another object of the invention is to provide means responsive to either remote electronic or manual stimulus to reverse the tape within a reader at any desired time.

Further objects and features of the invention will become apparent from the following description, which is taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a functional block diagram generally illustrating the functions carried out by the tape reader and data utilization device, such as a printer, of the present invention and showing the relationship between various fundamental functions;

FIGS. 2-9 are individual portions of a logic diagram setting forth an illustrative embodiment of the invention;

FIG. 2 comprises the elements operative to initiate reader operation, control generation of reverse stepping pulses, and respond to teleprinter control during transmission;

FIG. 3 comprises the elements for establishing different delay conditions in response to line feed commands, and the elements for detecting the tape-out condition;-

FIG. 4A comprises the gates for developing the Advance and Read signal for the tape reader and the elements responsive to the synchronizing signal from the teleprinter;

FIG. 48 comprises the elements for initiating and indicating the READ NEXT, OMIT NEXT, and BACKSPACE modes of tape reader operation;

FIG. 5 comprises the elements for initiating the selection of character, word, or line discrimination in the READ NEXT and OMIT NEXT modes;

FIG. 6 illustrates typical elements for providing the outputs from each channel of the tape reader to the control system and to the associated equipment;

FIGS. 7A-7C illustrate several typical decoding circuits responsive to the characters appearing under the head of the tape reader to produce control signals;

FIG. 8 comprises the elements for developing forward stepping pulses for the tape reader, for performing PARITY EDIT operations, and for performing SKIP DELETES operation; and

FIG. 9 comprises elements operative to permit teleprinter control over the tape reader in the event that it receives incorrect data.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Description FIG. 1 is presented to illustrate the basic functions that can be performed by the tape-reading system of the present invention. In this figure, various functions are denoted by blocks and the relationship between the blocks is also depicted. It should be understood that not all of the functions that can be performed by the equipment appear in FIG. 1. In order to appreciate the full capability of the system, the reader is directed to the more detailed circuit description made hereinafter in conjunction with the logic diagrams of a particular embodiment.

In the illustrated embodiment, use is made of a punched tape reader that is responsive to pulses to advance or backspace by one step with each pulse. Each step places the bits representative of a single character in the reading posi tion. Thus, the character can be determined and the reader controlled in response thereto. If the character should not be forwarded to connected equipment, the control system will make suitable provisions. It has been assumed that recording tape provides nine output indications. These may be developed in the conventional manner with photoelectric means which detect the presence or absence of the punched holes in the tape, as well as the sprocket holes. The presence or absence of a hole is indicated on a respective output lead. When a hole is present, the corresponding output lead provides a signal which will be considered in the following control logic as being a logic 1 signal.

The tape reader system of the invention can function in four discrete operating modes. These modes are: RUN, READ NEXT, OMIT NEXT, and BACKSPACE. Pushbuttons are provided to establish each mode of operation and the particular circuit functioning will be described and made clear in connection with the following detailed description of the invention. FIG. 1 relates fonned in the various operating modes.

The Tape Reader 1-10 appears in the upper central portion of FIG. 1. The output of Tape Reader 1-10 which consists of the aforementioned nine signal leads is applied to a Decoder 1-23 and Data Gate l-24. Decoder 1-23 produces binary signals on individual leads. These signals are employed by the control system to initiate and terminate the various operations of the tape reader. The decoder monitors each character as it appears in the reading position on the tape reader.

When it is desired to start operations, Run/Stop circuitry 1- 13 is activated and provides a start impulse via Reader Controls 1-12 to Tape Reader 1-10. When this occurs, the Reader will read the character appearing in the read position and advance one step. A Teleprinter l-ll is illustrated in conjunction with the reader control system. The Teleprinter 1-11 is responsive to the information presented thereto via Data Gates l-24 and after it has completely digested the information, it returns a synchronizing signal to Advance And Read Gates 1-25 which indicates to the Tape Reader control system that a further reading cycle should be initiated. It should be noted that the first operation of the tape reader requires a start impulse from Run/Stop circuitry l-l3. Thereafter, the Teleprinter, or similar equipment, produces the necessary synchronizing signals for continuously advancing the Tape Reader.

In most situations, the synchronizing signals from Teleprinter 1-11 will successively initiate the reading cycles. However, special Delay means 1-27 and 1-28 are provided for delaying the synchronizing signal when a preceding character has commanded teleprinter mechanical operations. For example, these delay means .operate when the commands call for a backspace, carriage return, achange in ribbon color, or a line feed. As a general rule, following any of these four commands, Decoder 1-23 activates a Long Delay circuit l-27 which inhibits operation of Advance And Read Gates 1-25 for the amount of time required to effect the called-for mechanical action of the Teleprinter 1-11. After this time has elapsed, the previously received synchronizing signal from Teleprinter l- 11 is effective via Gates l-25 to generate the Advance And Read signal.

It will be appreciated that sometimes the character following the line feed command will not be a printable character such as a hell, or a second line feed command. Where this is the case, it is not necessary to delay the reading of this character because the character will not require the teleprinter to effect a printing operation. Accordingly, the Decoder 1-23 determines whether or not the succeeding character is a printable character. In the ASCII code system, printable characters have either bit-6, or bit-7, or both b'its present in their code. Thus, the presence of either of these bits can be easily detected. If a printable character does not occur following an LP, the next line feed or non-printable character command causes Short Delay l-28 to inhibit the generation of the next Advance And Read signal in response to the synchronizing pulse from Teleprinter 1-11. Thus, it is seen that in order to completely minimize the delays required by line feed, carriage return, etc., two distinct delay circuits are provided in the present invention.

In connection with the editing aspects of the invention, attention is directed to the left-hand portion of FIG. 1. The control system makes it possible to review the data on the tape before it is forwarded to subsequent equipment. In most instances this capability is used in conjunction with the high speed omission features of the invention. However, with minor generally to the functions that are permodifications, this capability can also be utilized in conjunction with data addition means.

When it is desired to read the information appearing on the tape in order to perform possible editing operation, Read Next circuitry 1-16. is activated. Following this, the operator selects circuitry 1-17, 1-18, or 1-1-9, depending upon whether it is the next Character, Word or "Line," which is of interest. When the selection is-made, the equipment automatically functions to slow down and read only the desired next character, word, or line. Assuming that it is the next character which is of interest, the Character Selection circuitry 1-17 initiates start of the Reader via Advance And Read Gates 1-25 and Reader Controls 1-12. The Tape Reader 1-10 operates to advance and read the next character. As soon as Decoder l-23 detects a sprocket signal, Comparator means 1-20 is activated to stop the Reader so that only one character will be read. A similar arrangement is provided for reading the next word or line. The distinction in operation comes about as a result of having to stop Tape Reader 1-10 upon detection of something other than sprocket holes. Thus, when one wishes to read the next word, a start Reader signal is generated and the Reader 1-10 will continue operation in response to synchronizing signals until the Decoder 1-23 detects the presence of a character denoting the end of a word. Some of these characters are space," horizontal tab," carriage return, and line feed." On the other hand, when one is interested in reading the entire next line, the Comparison means 1-19 will permit operation of the Tape Reader 1-10 until a carriage return or line feed signal is detected by Decoder 1-23.

Having selectively moved the Tape Reader 1-10 in order to consider the character, word, or line presented thereby, it becomes possible to effect automatic omission of these characters rather than forwarding them to connected equipment. When it is desired to omit a character, word, or line. Omit Next circuit l-.15 is activated. In this operating mode, the Character, Word, or.l..ine circuitry 1-17, 1-18, 1-19, is effective to function until appropriate codes are detected by the Decoder and used to terminate the particular function being performed. A specific unique feature of the invention relates to the provision of Rapid Advance means l-26 which is operative in the event of Omit Next operation with Rapid Advance means l-26, rapid advance signals are applied to Tape Reader 1-10 during omission of data so that is is not necessary to await the usual slower occurring synchronizing signals from Teleprinter 1-11, In this way, a minimum amount of time is lost and high-speed handling of the data is effected.

This high-speed operation is also called into play when Parity Edit or Skipping Functions are being performed.

In order to understand the functioning of the Parity Edit features of the invention, it will be recalled that when tape is initially prepared, it is common to insert the characters NAK and ACK at the end of blocks of data in accordance with whether or not the preceding material satisfies parity conditions. When using the Parity Edit feature of the invention, the tape is inserted in a reverse direction and the Reader l-l0 is started. When the Decoder 1-23 reads a NAK" character, the Parity Edit circuitry 1-29 immediately enables Rapid Advance means l-26 and the tape advances at a rapid rate without the reading of data until and ACK" signal is detected by Decoder 1-23. At this time, the Reader 1-10 is slowed to its normal operating speed and goes through the normal reading cycles in response to each synchronizing signal received.

The high-speedoperation of the Tape Reader, without forwarding data to other equipment, is also advantageous in implementing the skipping of undesired portions of data. Such skipping is implemented by Skip circuitry l-31 which is enabled when a character is detected by Decoder 1-23 that signals the start of such undesired portions. The following logic schematics illustrate the use of this skipping feature to skip delete characters. This is of particular value since such characters are generally entered on the tape simply to obliterate errors or create time delays, not required in the advanced equipment IUIUIOB] contemplated herein. On the other hand, the skipping circuitry can also be activated by indented material, tables of figures, and any other desired material that can be detected by the presence of distinctive characters.

CIRCUIT SYMBOLOGY The logic diagrams of FIGS. 2 through 9 are composed primarily of flip-flops and NOR logic gates. For convenience in understanding the functions of the various components, the flip-flops are designated with a two-part designation. In this designation, the numerical prefix represents the figure in which the element appears and the alphabetical suffix is generally a word or acronym descriptive of function performed by the flip-flop. For example, flip-flop 2-RUN appears in the left central portion of FIG. 2 and is placed in a set state in order to initiate the RUN operating mode. Similarly, flip-flop 2-SRV appears in FIG. 2 and is placed in a set state to Start Reverse operation of the Reader. The leads and other elements also bear numerical prefixes indicative of the figure in which they originate; however, numerical suffixes are used in order to difierentiate between the various elements in each figure.

As a further aid in understanding circuit operation and recognizing the leads over which important control signals are applied, functional lead descriptions are sometimes used in addition to the numerical designations. These functional descriptions are associated with the appropriate leads by means of small arrows. For example, lead 9-18 on the left edge of FIG. 2 is designated "Trigger Start Reverse." This indicates that the signal for triggering the start of reader reverse drive is transmitted by this lead. The bar placed over this functional lead description indicates that the operative signal is a logic 0. The absence of such a bar indicates that the operative signal is a logic I.

The NOR logic gates used in the circuitry are of conventional design. The logic function NOR in Boolean Algebra is well known and can be defined as follows for a two input gate: If one or both inputs have a logic I applied thereto, the output will assume a logic state. Stated another way, if neither one input nor the other input has a logic I applied thereto, the output will assume a logic I state. Two types of symbols have been used for illustrating the NOR gates. One of these symbols (e.g., see gate 2-16 on the left of FIG. 2) has small circles on the input leads. This symbol is used where the desired operative output is a logic I. The other symbol (e.g., see gate 2-20 on the left of FIG. 2) has a small circle on the output lead. This symbol is used where the desired operative output is a logic 0. Although the symbols are different, the gates may be physically the same and they both perform the same NOR operation.

The standard flipflop used in the circuit diagram has five input terminals and two output terminals. The specific function of each terminal has been included in the illustration of typical flip-flop 2-R, appearing in the center of FIG. 2. The application of logic l to the set input will place the flip-flop in a set" state. The application of a logic 1 to the reset input will place the flip-flop in a reset" state. When "set" the flip-flop provides a logic I at its set output and a logic 0 at its reset output. The reverse is true of the reset" state.

Generally, a flip-flop is operated by the application of trigger pulses to the trigger input. A trigger pulse is one which goes to a logic I condition. Frequently these pulses are provided in a uniform train from a clock pulse generator. In response to a trigger pulse, a flip-flop assumes the state dictated by the signals on its set steering and reset steering inputs. The application of a logic 0 to either steering lead will be effective to switch the flip-flop so that the corresponding output provides a logic 1 upon occurrence of the trigger pulse. If the corresponding output of the flip-flop is already at logic I, no change of state will occur. It will be noted that the steering leads have small circles thereon. This is consistent with the previously noted convention that such circles indicate that the operative signals applied to these leads must be logic 0. Often, the steering leads are shown connected to a circle enclosing a negative sign, or to a ground" symbol. The former connection denotes a logic 1 source, and the latter, a logic 0 source.

In keeping with other symbol conventions, the output leads of the flip-flop can be identified by the source. Thus, the lead associated with the set output of flip-flop 2-R may be designated 2-R and the lead associated with the reset output may be designated 2-R.

Consideration will now be given to the detailed logic schematic drawings set forth in FIGS. 2 through 9. Since the illustrative embodiment of the control system is described in conjunction with a tape reader interconnected to a teleprinter, the tape reader and teleprinter are represented by dashed line boxes at the top of FIG. 2. Each box shows the pertinent input and output signals associated with typical equipment of this type.

RUN MODE OF OPERATION Since the teleprinter provides synchronizing signals for the initiation of tape reading cycles, it is necessary to provide a start read pulse only at the at the beginning of the RUN operating mode. Thereafter, the tape reader will receive through the control system, FORWARD STEP signals that are initiated by the teleprinter. On the drawings, the synchronizing signal is labeled RNC (Read Next Character).

Assuming that power has been supplied, the tape reader system is placed in a RUN mode by depressing the Run/Stop button appearing at the upper left comer of FIG. 2. This removes the logic 1 from the set-steering input of flip-flop 2- RUl. Accordingly, on occurrence of the next CPl clock pulse from Clock Pulse Generator 2-CPGI, flip-flop 2RU1 assumes a set condition and a logic 0 appears at the reset output thereof. This logic 0 is applied over lead 2-10 to the set-steering input of flip-flop 2-RU2. Thus, upon the next appearing CPl clock pulse, flip-flop 2-RU2 assumes a set state and provides a logic 1 at its set output. The latter signal is applied via diode 2-1] as a trigger pulse to the Run flip-flop 2-RUN which is connected to be self-steering, i.e., its set output and reset output are interconnected to the set-steering and reset-steering steering leads, respectively. Accordingly, the effect of the logic 1 signal applied via diode 2-11 is to always switch the state of flip-flop 2-RUN. The state of flip-flop 2-RUN indicates whether or not the equipment is to either begin operation or cease operation.

Flip-flops 2-RU1 and 2-RU2 are provided simply in order to prevent any momentary switch contact bounce of the Run/Stop pushbutton from effecting the repetitive operation of flip-flop Z-RUN. Obviously, other means could be provided for effecting this operation. As soon as the pushbutton is released, it connects a logic 1 to the reset terminals of both flip-flops and they return to the reset condition.

Clock Pulse Generator Z-CPGI provides synchronizing pulses for the entire control system. In the particular implementation of the invention described hereinafter, the signal provided by the clock pulse generator was a 20 microsecond logic 1 pulse that was applied at a repetition rate of approximately l 20 per second.

The four operating modes of the control system are controlled by the condition of Run flip-flop 2-RUN, Read Next flip-flop 4-RN, Omit Next flip-flop 4-ON, and the Backspace flip-flop 4-BS. Circuitry is provided, as described subsequently in connection with FIG. 4, to initially place each of the four flip-flops in the reset condition. During subsequent operation of the circuitry, only one of these flip-flops will be permitted to remain in a set condition at any time. Thus the flip-flop that is set will establish the mode in which the circuit is operating.

Having set Run flip-flop 2-RUN, it is necessary to generate the start pulse for presentation to the tape reader so that the first read cycle may begin. This start pulse is generated by the Start Reader flip-flop 2-SR appearing in the lower left quadrant of FIG. 2. When Run flip-flop 2-RUN is set, a logic l triggering pulse is delivered over lead 2-12 to the trigger input of Ran flip-flop 2-RA. The set-steering input of Ran flip-flop 2-RA has a logic provided thereto; thus, upon appearance of the trigger pulse, flip-flop 2-RA switches to a set state. The switching of flip-flop 2-RA is effective via NOR gate 2-13 to apply a logic 0 to the set-steering input of Start Reader flipflop 2-SR. Since the Start Reader flip-flop is thereby steered to a set condition, the next triggering impulse applied thereto from Clock Pulse Generator 2-CPG II, will set it.

Clock Pulse Generator Z-CPG II provides a signal that assumes a logic I state at intervals of l2 microseconds and has a duration of approximately l.5 microseconds. Obviously, both clock pulse generators can be designed in any suitable fashion.

The setting of Start Reader flip-flop 2-SR, supplies a logic I signal via lead 2-14 to the reset terminal of flip-flop 2-RA, and consequently places it in a reset condition. The reset output of flip-flop Z-SR is connected to its reset-steering input. Thus, upon the next occurring 2-CP2 clock pulse the Start Reader flip-flop itself will be reset. Thus, during its set condition, the set output of flip-flop 2-SR provides a 12 microsecond wide logic 1 signal.

Reference is made to FIG. 8. The logic 1 generated at the set output of Start Reader flip-flop 2-SR, is applied via NOR gates 8-10, 8-11, and 8-12 to the set-steering input of the Step flip-flop 8-STEP appearing at the center of FIG. 8. As a result of the inversions in each of the NOR gates, this set-steering signal is of the appropriate logic 0 state. Thus, upon occurrence of the next CP2 clock pulse on the trigger input of step flip-flop S-STEP, this flip-flop will be set. The setting of flipflop 8-step is effective through gates 8-13, 8-14, 8-15, and 8- 16 to provide a very narrow Forward Step pulse at the output of NOR gate 8116. The development of this pulse includes the use of the differentiating circuit 8-18 connected between gates 8-14 and 8-15. The pulse is applied to the tape reader and will cause the tape to be advanced by one character. As mentioned previously, this is the only start pulse that needs to be generated by the control system. All subsequent synchronizing pulses will be supplied by the teleprinter when it is ready to receive the next character.

It will be noted that a number of additional inputs are illustrated for the various gates thus far encountered. Where necessary, the application of signals to these inputs will be described in detail hereinafter. Where the specific mention of these inputs is not made, the source of the signals is made obvious by the lead designations. An understanding of circuit operation in response to such signals will be possible since the functioning of the circuit elements is easily appreciated. It is believed that the specific recitation of the signal paths followed and the component operation in response to each signal, would unnecessarily burden the discussion of this illustrative embodiment of the invention.

READER SIGNAL HANDLING AND DECODING Having noted the manner in which the Forward Step signal is generated and presented to the Tape Reader, it is worthwhile to consider the nature and handling of outputs from the Tape Reader. For this purpose, attention is directed to FIG. 6. The circuits illustrated in FIG. 6 represent the nine outputs from the Tape Reader. Circuits 1 through 7 provide the 7 coded bits of each character and circuit 8 provides the parity check bit. The ninth circuit provides the sprocket signal. The first seven channels from the Tape Reader are applied to transistors 6-11 through 6-17. The outputs of the transistors are applied to a series of gates 6-21 through 6-27 which inhibit transfer of information to the teleprinter or similar equipment until an enabling signal 8-STEP is provided. This enabling signal is generated at the reset output of Step flip-flop 8-STEP when the flip-flop is in a set state.

The equipment is designed to read the character resting in the reader first, and then advance the tape by one step to the next character position. In order to assure a correct signal being transferred to the teleprinter, it is necessary to provide a strobe pulse which will be delayed sufficiently after the 5- STEP pulse has opened the gates. This strobe is provided to the teleprinter by a Reader Strobe flip-flop 8-RS appearing in the upper central portion of FIG. 8. The setting of Step flipflop 8-STEP provides the necessary logic 0 steering signal to Reader Strobe flip-flop 8-RS. Consequently, upon occurrence of the next CP2 triggering signal, Reader Strobe flip-flop 8-RS is set and provides a logic 1 output at its set terminal. This Reader Strobe signal is supplied to the Teleprinter to indicate that the data presented from the Tape Reader may be accepted. Upon receipt of all information from the Reader, the teleprinter in any known manner will return a signal labeled Strobe In. The Strobe In signal is supplied to the reset terminals of the Step and Reader Strobe flip-flops S-STEP and 8- R8 in order to reset them. At a somewhat later time, after the teleprinter has digested and completed its read-in functions, it will provide the necessary RNC synchronizing signal to reinitiate the read and .advance cycle previously described.

Before proceeding with a description of the circuit operating during normal response to the various possible commands, reference is made to FIGS. 7A through 7C. These figures illustrate typical decoding circuits which operate to provide discrete signals in accordance with the detection of certain important characters in the reading position at the TAPE Reader. Referring to FIG. 7A, it will be seen that there are seven diodes. The input to each of these diodes is designated by a number from 1 to 7 which is either barred or plain. These input indications represent the signal bit of the various channels on the tape for a particular character. Recalling that we have assumed use of the ASCII code system, it will be seen that a discrete output is provided from this particular decoding circuitwhen. a logic 1 appears at the terminal labeled sprocket," and with the character I l l l l l l appearing on the tape. This isthe delete character in which all possible holes arepunched. Under this condition a logic I signal will be provided on the lead marked EL" and a logic 0 will be provided on the lead marked DEL."

Other typical decoding circuits are shown in FIG. 7B and FIG. 7C. In the case of FIG. 78, when the character that is read has the binary code 0l0l000, a logic 1 will appear on the lead labeled LF." This indicates that the character is a Line Feed command in accordance with the ASCII code designations. Similarly, when' the character is 01 10000, a logic I will appear on the ACI(" lead. This indicates that an acknowledgement signal has been obtained from monitoring equipment and that the previously printed data block satisfies all parity conditions. Similar decoding gates are provided for developing positive signals for any particular character that will be used in conjunction with the initiation or implementation of operations by the tape reader control system.

READER DELAY OPERATIONS As previously mentioned, depending upon the character stored in the tape, various actions must be taken by the control circuitry. For example, it is necessary to halt the flow of charactersfrom the Tape Reader to the Teleprinter, momentarily after delivering a Carriage Return" signal code, in order to permit the mechanical carriage return action to be carried out. The delay is effected by preventing immediate response to the synchronizing RNC pulse from the Teleprinter and thereby delaying the generation of .the Forward Step pulse that is normally supplied to the Reader. The Read Next Character flip-flop 4-RNCS appearing in the upper portion of FIG. 4A, in cooperation with gates 4-12 through 4-21 provide modifying circuitry which will either permit immediate response to the synchronizing pulse or delay the response.

In the lower right quadrant of FIG. 3, there is a timing circuit made up of resistor and capacitor-timing elements and gates 3-10 and 3-11. This timing circuit is activated by the output of gate 4-14 in FIG. 4 and the output of gate 3-12 in the left center portion of FIG. 3. Long delay flip-flops 3-LD1, 3- LD2, and 3-LD3 function in cooperation with the timing circuit.

In essence, gate 4-14 operates to provide a logic whenever the Decoding circuitry detects a change ribbon (ECS), a backspace (BS"), or a carriage return (CR) code. This is illustrated on the drawings by the logic notation ESC+BS+CR. The logic 0 signal is applied to the set-steering lead of long Delay flip-flop 3-LD1. The RNC synchronizing pulse from the Teleprinter is applied as the trigger to this flip-flop; accordingly, when the RNC pulse is provided, it will set flip-flop 3-LD1. The logic l appearing at the output of flip-flop 3-LD1 is applied via gate 3-12 to the set-steering input of flip-flop 3- LDZ. Upon occurrence of the next CP2 clock pulse. flip-flop 3-LD2 will be set. The resulting logic 0 signal at the reset output of flip-flop 3-LD2 is applied to the set-steering lead of flipflop 3-LD3, and upon occurrence of the next CPI clock pulse, flip-flop 3-LD3 is set.

The setting of flip-flop 3-LD3 provides a logic 1 signal which resets flip-flop 3-LD1 via lead 3-13. This signal is also applied to the reset input of 3-LD2 via lead 3-14. The resetting of the latter mentioned flip-flop removes the set-steering from flip-flop 3-LD3. The reset output of flip-flop 3-LD3 is connected to its reset-steering input and it is therefore reset upon appearance of the next CPl clock pulse.

While it is set, the logic I appearing at the set output of flipflop 3-LD3 is applied to one input of the gate 3-11. This forces the output of gate 3-11 to go to a logic 0 for the period of the triggering of clock signal CPI. The logic 0 signal is applied to capacitor 3-15 in order to discharge it and reset the timer in the event that it was previously in the middle of a timing cycle. At the same time, the logic 0 output on the reset output of 3- LD3 discharges capacitor 3-16.

When the next appearing CPl clock pulse resets flip-flop 3- LD3 the negative going output on the reset output lead is differentiated by capacitor 3-16 and resistor 3-17 and applied to one input of gate 3-10. This forces the output of gate 3-10 to logic 0 and this is applied to one input of gate 3-11. Since the reset of flip-flop 3-LD3 places a logic 0 on the other input, gate 3-11 provides a logic 1 signal on lead 3-40. This marks the beginning of the timing cycle. The logic l signal is applied via a timing circuit comprising capacitor 3-15 and adjustable resistor 3-19 to an input of gate 3-10. This closed loop arrangement maintains a logic l at the output of gate 3-11 for the duration of the time interval set by the adjustable resistor 3-19.

Reconsidering again the instant of time at which flip-flop 3- LD3 is set, it will be noted that the set output thereof is applied to gate 4-12 in FIG. 4A. This lead will be at logic I and accordingly a logic 0 output will be provided from gate 4-12 to one of the inputs of gate 4-15. The other input of gate 4-15 is the 3-LD signal from the output of gate 3-11. It will be recalled that at this time, the 3-LD signal is in a logic 0 state as a result of the resetting of the timer which occurs upon setting flip-flop 3-LD3. Thus, a logic I is presented at the output of gate 4-15 and is applied to gate 4-20 which in turn presents a logic 0 to an input of gate 4-21. As will be explained hereinafter, the Omit Next signal 4-ON and the Start Up Reset signal will both be at logic 0 at this time. Therefore, the logic 0 output from gate 4-20 will result in the generation of logic I at the output of ga3e 4-21. This is the Advance And Read signal that is applied to gate 8-10 to develop a Forward Step signal for the Tape Reader. In response thereto, the Reader forwards the ESC, BS, or CR command character to the Teleprinter. It is now necessary to determine whether or not the succeeding character on the tape is a printable character. If so, the control system will have to delay the Reader operation in response to the next RNC synchronizing signal.

The RNC pulse is received from the Teleprinter at the trigger input of Read Next Character flip-flop 4-RNCS. This flip-flop is permanently steered so that upon receipt of the RNC synchronizing signal, it will be set. As illustrated in the figure, the reset input of flip-flop 4-RNCS receives the Strobe In signal from the Teleprinter. It is this signal that indicates the Teleprinter has completed all action in response to the preceding character. Thus, flip-flop 4-RNCS is automatically set in response to the RNC signal and reset in response to the Strobe In signal.

Gates 4-10 and 4-11 function to determine whether or not a character is printable. Since printable characters in the ASCII code system have either bit-6, bit-7, or both present in their codes, gate 4-10 has input signals from channels 6 and 7 of the reader. The operation of gate 4-10 results in the presentation of a logic 0 output when either bit-6 or 7 is a logic I. The only time this logic 0 output is ambiguous is when the character is delete. In order to eliminate this ambiguity, the Decoder provides the DEL" signal as one input of gate 4-11. Thus, the output of gate 4-11 will only be at logic I when there is a printable character that is not a Delete, and an RNC signal has previously set flip-flop 4-RNCS. The logic 1 output from gate 4-11 is used to drive the trigger input of Printable Character flip-flop 4-PC. The reset steering input of flip-flop 4-PC is permanently held at logic 1 whereas the set steering input is provided with a signal that will be at logic 0 when the character being read is not a space (SP"). Thus, flip-flop 4-PC is set when there is a printable character resting in the read position of the Tape Reader.

When the timing circuit comprising elements 3-15 and 3-19, in the lower right portion of FIG. 3, has timed out, signal 3-LD at the output of gate 3-1 1 will assume a logic 0 state. This logic 0 is applied to one input of gate 4-18. The other input of gate 4-18 is connected to the reset output of Printable Character flip-flop 4-PC. Accordingly, if flip-flop 4-PC is in a set condition indicating that a printable character is ready to be read and that the RNC-synchronizing pulse has been received, the flip-flop will provide a logic 0 to the second input of gate 4-18. The output of this gate then goes to logic I and the application of the logic 1 signal through gates 4-20 and 4-21 results in the generation of a logic 1 Advance And Read signal.

It will be recalled that the time delay operation just described in response to the detection of a Carriage Return (CR") signal by the decoder circuitry. A similar delay is required in the event of a command for either Backspace or Ribbon Change. Where these characters are detected, logic I signals are applied to gate 4-14 and this is effective to initiate the timing cycle just described.

Somewhat different considerations are applicable in the event that the character Line Feed (LF") is detected. In this case, it is necessary to delay reading of any subsequent printable character; however, as previously mentioned, the delay I need not be as long as the one previously described, if the character or characters between the first and second line feeds are not printable characters. Thus, if a printable character follows the LF character, it is necessary to start the longer timer just described. On the other hand, if a nonprintable character (e.g., another LF") follows the LF character, a shorter timer may be initiated, thereby permitting the Teleprinter to rapidly make repeated Line Feeds.

The signal on the set output of flip-flop 4-PC is applied to the set input of flip-flop 3-PCLF in the right center portion of FIG. 3. The reset-steering input of flip-flop 3-PCLF is at a logic 0 when a Line Feed character is detected by the Decoder. Thus, flip-flop 3-PCLF is set if there has been a printable character detected since the last Line Feed command, otherwise it is reset. Flip-flop 3-CLF has its set-steering input at logic 0 when there is a Line Feed character in the printer. This flip-flop is triggered by the set output of the Read Next character flip-flop 4-RNCS. Thus, when the character is a Line Feed character, upon occurrence of an RNC signal from the Teleprinter, flip-flop 3-CLF will be set. When both flip-flop 3-PCLF and flip-flop 3-CLF are set, a logic 1 is presented at the output of gate 3-27 which is effective via gate 3-12 to set steer Long Delay flip-flop 3-LD2. The next occurring CP2 clock pulse sets flip-flop 3-LD2 and thereby initiates operation of the Long Delay Timer as previously described.

If no printable character has been detected since the last Line Feed command, it is desired that a shorter time be taken prior to reading of the next character. The shorter timing is effected by the timing circuit shown in the upper portion of FIG. 3. The timer consists of flip-flops 3-SD1 and 3-SD2, and includes timing circuitry comprising capacitor 3-25 and adjustable resistor 3-26.

The conditions for setting the Short Time Delay are established by connecting the reset output of flip-flop 3-CLF and the set output of flip-flop 3-PCLF to the inputs of gate 3- 20. When both inputs of gate 3-20 are at logic 0, it supplies a logic I trigger pulse to flip-flop 3-SD1. The permanent set steering of this flip-flop causes it to set in response to the trigger pulse, and this in turn set steers flip-flop 3-SD2. Flipflop 3-SD2 is set by the next occurring CP2 clock pulse. The setting of flip-flop 3-SD2 produces a logic at the output of gate 3-24 which is effective to initially reset the timing circuit comprising capacitor 3-25 and adjustable resistor 3-26. As was the case of flip-flop 3-LD3, flip-flop 3-SD2 is self-steered to reset and therefore resets upon occurrence of the next CPZ pulse. This starts the timing cycle. In a reset condition, flipflop 3-.SD2 set steers flip-flop 3-SD3 and when the timing cycle has been completed flip-flop 3-SD3 will be triggered to the set state and produce a logic 1 signal at its set output. The logic I signal at the set outputof flip-flop 3-SD3 is applied to gate 4-12 in the same manner that the output of flip-flop 3- LD3 was applied thereto. As a result, an Advance And Read signal will be produced via gates 4-12, 4-15, 4-20, and 4-21 after the shortened time has elapsed.

In the event that the longer delay timer is activated prior to initiation of the shorter delay, the longer timer will override the shorter timer as a result of the action of the 3-LD input to gate 4-15.

All other nonprinting characters that may appear in the tape being read are effective without delay to generate Advance And Read pulses at the output of gate 4-21. The circuitry for implementing this generation of pulses includes gates 4-13, 4- 16, 4-19, 4-20, and 4-21. If the character is nonprintable and not LF, gate 4-13 provides a logic I to gate 4-16. Gate 4-16 produces a logic 0 output when the character is either a Delete or nonprintable or LF." Recall that gate 4-14 produces a logic I only if the character is not ESC," BS," or CR." This being true, inverting the output of gate 4-14 with gate 4- 17 provides a logic 0 when the character does not require a Change Ribbon, Backspace, or Carriage Return. The outputs of gates 4-16 and 4-17 are applied along with the reset output of flip-flop 4-RNCS to gate 4-19 and will generate a logic 1 output therefrom when nonprinting characters other than the three specified, are read. This output will produce the Advance And Read signal via gates 4-20 and 4-21.

TAPE OUT CONDITION It is desirable to stop the Tape Reader when it runs out of tape. Preferably this should be done electronically and not by a mechanical sensing means. In accordance with the present invention this condition is sensed by noting that repeated forward or reverse step pulses are applied to the Tape Reader without receiving the corresponding sprocket hole signals which are normally produced when the sprocket hole sensor sees paper and holes alternately.

The impulses commanding forward or reverse steps are not only sent to the Tape Reader, they are also applied via gates 3- 31 and 3-32 to the trigger input of Step flip-flop 3-ST appearing in the lower left quadrant of FIG. 3. Flip-flops 3-ST and 3- T0 are connected as a two-stage binary counter. When a tape is in place, the step impulses will register a count and the sprocket signal will reset the counter. The resetting is effected through a plurality of gates 3-33 through 3-37. Gates 3-33, 3- 34, and 3-35 insure that the equipment is in one of its operating modes. Gate 3-36 provides a logic 0 output if the equipment is in one of the operating modes, a Startup Reset signal is applied, or there is a sprocket signal, A count of two will result in the setting of Tape Out flip-flop 3-TO. When this occurs the set output of flip-flop 3-TO is efiective via gates 4-22 through 4-25 in FIG. 48 to reset flip-flops 2-RUN, 4-RN, 4-ON and 4- B8. In other words, the control system is placed in a stop mode.

14 READ NEXT OPERATION Thus far, the circuit operation in response to general operating conditions following a start impulse has been described. Attention will now be directed to the specific editing functions which the present reader control system is capable of performing. The first of these functions involves the controlled .slowing of the Reader in order to determine the next character, word, or line. This is an essential operation preparatory to either accepting the information that is to be presented or modifying it in order to correct it. At the bottom of FIG. 48 three flip-flops are illustrated. These flip-flops control the operating modes: Read Next, Omit Next, and Backspace, respectively.

The Read Next operation is initiated by closure of the Read Next pushbutton appearing in the lower left corner of FIG. 4B. This supplies a logic 1 signal to the set input of Read Next flipflop 4-RN, placing it in a set state. The logic I l signal applied to the set terminal of flip-flop4-RN upon depression of the Read Next pushbutton is also applied via diode 4-28 and lead 4-30 to the trigger input of flip-flop 4-ON and 4-BS. The result of this application to the-latter flip-flops guarantees that they are switched to a reset state in the event that they were previously set. It will be noted that the set-steering input of each of the flip-flops is permanently at. logic 1, whereas the resetsteering terminals are permanently at logic 0.

If it is desired to read only the next character on the tape, and then stop-the reader, this is accomplished by depressing the character pushbutton appearing in FIG. 5. The set-steering inputs of each of the flip-flops S-CHAR, S-WORD, and 5- LINE are all connected to the output of gate 5-13. The inputs to this gate are the 4-RN signal and the 4-ON signal generated at the set output of the corresponding flip-flop in FIG. 4. Thus, when either the Read Next or Omit Next flip-flops are energized, a logic 1 will be presented to the input of gate 4-13 and the output thereof will be logic 0, thereby set steering the associated flip-flops. Thus, operation of the character pushbutton applies a trigger pulse to flip-flop S-CHAR and it is set. The consequent logic I signal appearing at the set output of flip-flop S-CHAR causes a logic 0 signal to be produced at the output ofgate 5-14. The inversion in connected gate 5-15 supplied a trigger pulse to flip-flop 5-OMIT appearing on the extreme right of FIG. 5. Flip-flop S-OMIT is permanently steered to a set condition Accordingly, when it is set, a logic 0 is produced at its reset output and in the absence of an Omit Next signal (4-ON), a logic I CWL start signal will be provided at the output of attached gate 5-16. This latter signal derives its name from the acronym for Character-Word- Line" start operation.

Referring to FIG. 2, it will be seen that the CWL start signal is applied via gate 2-13 to the set steering lead of the Start Reader flip-flop 2-SR. Consequently, upon appearance of the next trigger impulse CP2, a Start Reader signal will be provided at the set output of flip-flop 2-SR and the read cycle previously described will take place.

Flip-flop S-OMIT has the tape out reset signal appearing on lead 3-38 applied as a reset input thereto. It will be recalled that these tape out reset signals are generally developed by the sprocket holes as the tape is read, and appear at the output of gate 3-37 in the lower portion of FIG. 3. After the tape has advanced one character position, flip-flop S-OMIT is therefore reset. The state of flip-flops S-CWLR and S-OMIT are compared at gate 8-]? in the left portion of FIG. 8. When flip-flop 5-OMIT is reset, gate 8-17 provides a logic I which resets Stop Strobe flip-flop 8-58. The resetting of flip-flop 8-SS blocks the incoming Advance And Read signal that is being applied via gates 8-10, 8-11, and 8-12 to the set-steering input of Step flipflop 8-STEP and thereby prevents generation of the Forward Step Signal. This blocking action is efi'ected by the application of the logic 0 from the set output of 8-88 to one input of gate 8-19. In order to generate the Forward Step impulse it is essential that one of the inputs to gate 8-19 be in a logic I state. The other input at this time is at logic 0 state because Run flipll0l056 flop 2-RUN is in a reset state. The logic 0 from flip-flop 8-SS makes the output of gate 8-19 a logic I and this prevents the set steering of flip-flop 8-STEP. The blocking action is very fast and will occur before the operator removes his finger from the character pushbutton. When the button is released its back contacts apply a trigger pulse to flip-flop S-CWLR via gates 5-11 and 5-12. The setting of flip-flop S-CWLR results in the application of a logic 1 signal to the reset inputs of each of the Character, Word, and Line flip-flops placing them in a reset condition.

In recapitulation it will be seen that, as a result of depressing the Read pushbutton and the Character pushbutton, a single Forward Step signal activated the Reader and the subsequently developed Advance And Read signal was blocked so that no further Forward Step signals were generated.

Consider next the operation of the circuitry when it is desired to read the next Word. In this instance, after first depressing the Read Next pushbutton in FIG. 4, the operator depresses the Word pushbutton in FIG. 5. Depression of the Word pushbutton results in the application of a triggering impulse to Word flip-flop S-WORD. Once again, it will be noted that this flip-flop is set-steered and therefore it will switch to a set condition. In the present instance, since it is desired than an entire word be read and because more than one character may makeup a word, it is necessary to permit more than one character to be read. Thus the signal to stop the Reader (i.e., block and Advance And Read signal by resetting flip-flop 8- 88) must be derived not from the sprocket signal as in the previous case, but from the decoding of one of the nonprinting characters which normally signal the end of a word. Typically, some of these characters are Space," Horizontal Tab, Carriage Return," and "Line Feed." Other such characters of signals will be obvious to the reader and decoding circuits for detecting the presence of such characters may easily be developed following the teachings of the circuitry shown in FIGS. 7A through 7C.

Gates 8-20 through 8-24 associated with the reset-steering input of the Stop Strobe flip-flop 8-SS provide the necessary control for resetting this flip-flop under the desired conditions. It will be apparent that these gates are arranged in order to insure that the flip-flop 8-SS has a logic 0 signal applied to its reset-steering input when either the Word or Line flip-flop 5- WORD and S-LINE are energized, and there is a Carriage Return, a Space, a Horizontal Tabulation, or an Off signal read from the tape. Under these conditions, the subsequently appearing Forward Step signal from the output of gate 8-47 will be applied as a trigger pulse to reset Stop Strobe flip-flop 8-SS. In the event that the Line pushbutton is pressed, there is a similar action in order to permit an entire line to be read. In this instance, only the presence of a Carriage Return signal can be operative to block further reading. This is effected by means of the gates 8-20, 8-21, and 8-22 associated with the reset-steering input of the Stop Strobe flip-flop 8-SS. Thus, the gate 8-20 will apply a logic 0 to one input of gate 8-21 when either the Line or Word pushbutton is pressed; in addition, the decoding of a C .irriage Return signal will result in a logic 0 applied to the other input. Accordingly, gate 8-21 produces a logic I at the output thereof which causes the logic 0 at the output of attached gate 8-22 to reset steer flip-flop 8-SS.

OMIT NEXT OPERATION Another aspect of tape-editing operations that can be extremely important is the facility for omitting either the next character, word, or line in a previously prepared tape. With the present invention, this is accomplished by first pressing the Omit Next pushbutton appearing at the lower central portion of FIG. 4. This provides a logic 1 set signal which switches the Omit Next flip-flop 4-ON to a set condition. It simultaneously insures, via suitably oriented diode 4-31 and lead 4-30, that companion flip-flops 4-RN and 4-88 are placed in a reset state. The logic 1 signal appearing at the set output of flip-flop 4-ON is immediately applied to one of the inputs of gate 5-16 in order to prevent the previously described reading action which would be initiated through gate 2-13 in FIG. 2.

The amount of material to be omitted is then selected by operating either the Character, Word, or Line pushbuttons in FIG. 5. The operation of the circuitry in response to the subsequently applied signals is substantially similar to that which occurred when reading was involved. Thus, first flip-flop 5- OMIT is set. Upon setting, the logic 1 signal appearing at the output of flip-flop 5-OMIT is applied to the set input of Hipflop 8-SS switching it to a set condition. Gate 8-25 is connected to the reset output of flip-flop 8-SS and it receives a full complement of logic 0 inputs upon the next occurring CPI clock pulse. It may be noted that during Read Next operation; the appearance of the 4-RN signal on one of the inputs to gate 8-25 blocked its operation. The logic I provided at the output of gate 8-25 is operative through gates 8-13, 8-14, 8-I5, and 8- 47 to produce Forward Step pulses for application to the reader.

In contrast with the previously described usual operations, in this mode of operation the forward step pulses are repetitively generated at a high frequency, without reliance upon synchronizing signals RNC from the Teleprinter. These pulses recur at the repetition frequency of the Clock Pulse Generator Z-CPG I. The Tape Reader stepping action will continue until flip-flop 8-SS is reset. The resetting of the latter flip-flop is accomplished in the manner aforedescribed and depends upon whether or not the Character, Word, or Line pushbutton is actuatcd.

SKIP DELETES There are times, as previously explained, when the Delete" character is used to obliterate other characters which were originally inserted into the tape in error. In these cases, it is advantageous not to read the Delete since time is wasted. Instead, it is preferable to omit them in a manner similar to the omission operation just described. In order to effect this type of omission, a Skip/Deletes switch is provided. This switch is shown in the upper right portion of FIG. 8. As arranged in this embodiment of the invention, when it is desired to skip/delete characters, the switch is opened. When system is in either the Run or Read Next operating modes, a logic 0 will be presented through gate 8-26 to one of the inputs of gate 8-27. Another logic 0 is provided to the input of gate 8-27 as a result of the connection through resistor 8-29. When the Decoding circuitry detects the presence of a Delete character as the reader, the third input of gate 8-27 receives a logic 0 thereon and this results in a logic I being presented at the output. Gates 8-28 and 8-30 are responsive to this logic I to provide a logic 1 setting pulse to the Delete flip-flop 8-DEL.

The setting of flip-flop 8-DEL presents a logic 0 to one of the inputs of gate 8-34. Another input of gate 8-34 is supplied via gates 8-3], 8-32, and 8-33. When a Delete character is detected these gates provide a logic 0 enabling signal to gate 8- 34 and it thereafter passes CPI clock pulses as long as flip-flop 8-DEL remains set. The resulting logic I pulses on lead 8-35 are applied to one of the inputs of gate 8-13 and initiate generation of Forward Step pulses at the repetition rate of Clock Pulse Generator 2-CPG 1.

After the institution of this Skip/Deletes operation, when a character other than Delete is presented at the Tape Reader. flip-flop 8-DF is set steered due to the removal of the logic I that the Delete signal applied to the input of gate 8-31. At this time, the output of gate 8-31 is a logic 1. The presentation of this logic 1 to the input of gate 8-32 results in the generation of a logic 0 at its output which is applied to the set-steering lead of the Delete Finish flip-flop 8-DF. Since Delete flip-flop 8- DEL. is in a set condition, it presents a logic 0 to one input of gate 8-36. The subsequently occurring CPI clock pulse therefore passes through gate 8-36 and triggers the Delete Finish flip-flop 8-DF to a set state. Upon setting, flip-flop S-DF resets flip-flop 8-DEL via lead 8-37. This prevents the passage of further clock pulses via gate 8-34 and lead 8-35. When flip- PARlTY EDIT OPERATION When a tape is developed in response to received data, it conventionally includes parity codes indicating whether or not the preceding block of data satisfies a parity check. If the block of data is correct, an ACK" code will be inserted. If the data is incorrect, a NAK" code will be inserted. When the tape is being edited, it may be submitted to the TApe Reader in reverse order so that the status character (ACK or NAK) will be read before the associated block of data. The present invention provides means for selectively omitting blocks of characters which are preceded by a NAK code.

In FIG. 8, the Parity Edit switch appears in the lower left quadrant. When this switch is open, the control system will omit data preceded by NAK characters. The decoding of a NAK character results in gate 3-38 having logic at both inputs; consequently, a logic 1 appears at the output thereof and this is inverted by gate 3-39 and applied as the set steering input of Omit Next Block flip-flop 8-ONB. Flip-flop 8-ONB is set upon the application of the Strobe ln signal from the Teleprinter. It will be recalled that the appearance of this signal indicates that the auxiliary device has received and digested the previous character. This triggering pulse provides a convenient timing pulse to assure that the NAK" signal has reached equilibrium prior to switching flip-flop 8-ONB. When flip-flop 8-ONB is set, the logic I at its set output is applied to gate 8-31. As in the case of the detection of a Delete signal from the Decoding circuitry, this results in the delivery of pulses at the repetition rate of Clock Pulse Generator CPl over lead 8-35 to gate 8-13. Accordingly, Forward Step pulses are supplied at this rapid rate to the Tape Reader. The high-speed skipping action will continue until the Omit Next Block flipflop 8-ONB is reset.

The resetting action is initiated by detecting the presence of an ACK" code in the tape. This code sets flip-flop 8-ACKS by placing a logic 0 on the set steering input thereto. The logic 0 is applied via gates 8-43 and 8-44. It will be seen that gate 8- 43 has both inputs at logic 0 when flip-flop 8-0NB is in a set state and the ACI(" signal is detected by the Decoding circuitry. When flip-flop S-ACKS is set upon occurrence of the next Forward Step pulse, it presents a logic 0 to the input of gate 8-45. The other input to gate 845 is a logic 0 when the presence of an ETB" or ETX" code is detected. By. intemational standards, the latter codes are positioned next to the ACK" code and will accordingly in this instance follow the ACK." Thus, a logic l signal is generatedat the output of gate 8-45 which sets search for NAK flip-flop 8-SFN and resets Omit: Next Block flip-flop 8-ONB. The setting of flipflop B-SFN restores the Reader to normal operating conditions by applying a logic I tothe set input of the Start Reader flip-flop Z-SR, thereby initiating generation of the Start Reader signal.

REMOTE CONTROL OPERATION It will be appreciated that there are times when the Teleprinter is being used to transmit data to a remote unit. At these times the data may be checked for errors at the remote site and the coded ACK" or fNAK" signals returned to the Teleprinter to indicate satisfactory or unsatisfactory transmission respectively. When transmitting from the Tape Reader, it must be stopped until the check for errors has occurred and then resume upon receipt of ACK." If the check shows an error and NAK is returned to the sender, the Reader must be reversedand the previous block of data reread and retransmitted.

If the Teleprinter is employing error detection, it will provide a logic 1 signal labeled 9-BCCF to gate 4-22 in FIG. 48 at the time the Reader is to be stopped. This stops the Reader in the same manner as the Tape Out condition previously described.

It will be appreciated that when the Teleprinter is being operated in this fashion, the control system will be either in a -Run or a Read Next mode. FIG. 9 contains the principal logic elements for effecting the desired controls in the particular situation envisaged. As shown in this figure, flip-flop 9-BCCR is set when the control system is in a Run mode and flip-flop 9- BCCRN is set when the system is in a Read Next mode. This is established by set steering the flip-flops with signals from the set outputs of the Run flip-flop 2-Run and the Read Next flipflop 4-RN, respectively. The BCCF signal from the Teleprinter is used as a trigger signal for these flip-flops.

1f the Teleprinter determines that it is advisable to repeat a block of data, it provides a reverse signal (REV) which is applied to the input of gate 9-15. Gates 9-13 and 9-14 are appropriately interconnected to the outputs of flip-flop 9-BCCR and 9-BCCRN so that at least one of these flip-flops must be set in order to provide a logic 0 output on gate 9-14. Gates 9- l4 and 9-15 both supply the input to gage 9-16. When both inputs are at logic 0, gate 9-16 provides a logic 1 output which is inverted in gate 9-17 to provide a Trigger Start Reverse signal on lead 9-18 which will initiate reverse stepping of the Reader. This signal is applied to gates 2-16, 2-19 and 2-21 appearing along the left-hand edge of FIG. 2.

1n order to prevent an endless cycle of read-error-reverse, a binary counter is provided in the form of flip-flops 2-A and 2- B illustrated in the lower center portion of FIG. 2. F lip-flop 2- A is set on the-first repeat of data; flip-flop 2-B is set on the second repeat of data. The outputs of these flip-flops are applied to ates2-16 and 2-20 in order to control the effect of the Trigger Start Reverse signal on the Tape Reader.

Assuming that the first repeat of data is requested and therefore the counter has not achieved its maximum count, gate 2-20 will set steer theStart Reverse flip-flop Z-SREV. When the Start Reverse flip-flop Z-SREV is thus set steered, the Trigger Start Reverse signal will be applied through inverter gate 2-19 to trigger the flip-flop into a set condition. The resulting logic 1 signal on the set output of the Start Reverse flip-flop Z-SREV is transmitted via lead 2-30 to the setinput of Reverse flip-flop 2-R. The logic I appearing at the set outputof. reverse flip-flop 2-R is then applied to gate 2-31 which also receives an input from the set output of Back Step flip-flopZ-BSF. The resulting logic 0 at the output of gate 2-31 is applied to the input of gate 2-32 and is effective to enable this gate topass CPI clock pulses as Reverse Step pulses to the Tape Reader. .When the-tape Reader is run in reverse, it will continueto do so until the Reverse Step pulses stop. This occurs when an-SOH" or STX" character code is detected in the tape. Those familiar with the ASCII code will recognize that these character codes indicate the start of a block of data.

When one of these codes, or the reader tape out condition occurs, the output of gate 2-33 becomes a logic 0 and reset steers Reverse flip-flop Z-R. Flip-flop Z-R is triggered by CP2 clock pulses and thus resumes the reset condition upon the next occurring CP2 pulse. Upon resetting, the reset output of flip-flop 2-R is applied as a trigger to set Start Run flip-flop 2- SRU. The set steering of the latter flip-flop will be explained hereinafter. .When flip-flop Z-SRU is set, it reinitiates the Run mode by setting Run flip-flop Z-RUN via gates 2-17 and 2-18.

If a second NAK" signal is received after repeating the data, this will result in increasing the count stored in flip-flops 2-B and 2-A. When the third NA1(" is received, the respective states of these counter flip-flops prevent the setting of the Start Reverse flip-flop Z-SREV and instead enable the set input of Run flip-flopZ-RUN. Thus, the system is returned to the Run mode without causing further reversals.

If, after a block has been transmitted, the Reader being at rest, an "ACK signal .is received from the remote unit, the Teleprinter will provide a signal of logic 1 value at the input of gate 2-23. This is effective to reset both counter stages Z-A and 2-B. The counter is also reset through gate 2-21 after it has reached the maximum allowable count. ln the latter case, this resetting is accomplished upon coincidence of the Trigger Start Reverse and the set condition of Start Reader flip-flop 2- SR. The receipt of an "ACK signal also results in the Teleprinter generating a forward (FWD) signal which is applied to gate 9-12 in FIG. 9. The FWD signal in combination with an indication that the Read Next flip-flop 9-BCRN is in a reset condition and that the Run flip-flop 9-BCCR is in a set condition will result in the generation of a logic 1 signal at the output of gate 9-13 which is used to set Start Run flip-flop 2- SRU in FIG. 2.

The above-described sequence of operation assumed the equipment was initially in a Run mode. In the event that the equipment is in the Read Next mode, a similar sequence of operation will occur. The difference resides in the fact that rather than having flip-flop 9-BCCR set, the Read Next flipflop 9-BCCRN will be set. Under these conditions, the system will be restored to the Read Next mode by flip-flop 9-BCCRN and interconnected flip-flop 2-SRN in FIG. 2. It is believed unnecessary to specifically trace the details of the latter circuitry in view of the fact that all of the interconnected gates have been considered in connection with resuming operation under the Run mode.

BACKSPACING This control system also provides for normally controlled backspacing of the Reader. The manner in which the Reverse Step signal is generated in response to the Teleprinter command has been explained. in order to that generation of this signal within the control circuit itself, the Backspace Pushbutton appearing in the lower right quadrant of FIG. 2 is provided. When this pushbutton is depressed, it applies triggering pulses from clock pulse generator CPG l to Backspace Pushbutton flip-flop Z-BSPB. The setting of the latter flip-flop provides a trigger signal to Backspace flip-flop 2-BSF and this in turn is set. Upon being set, flip-flop 2-BSF applies a logic 1 signal to the input of gate 231 and as previously described, this resultsin the application of a Reverse Step pulse to the printer at the output of gate 2-32. The next occurring CPl clock pulse resets flip-flop 2-BSF and when the pushbutton resumes its initial position, flip-flop Z-BSPB is reset. Thus, a single step in the reverse direction is made.

in order to insure that the other modes are not disturbed during this type of backspace operation, the output of flip-flop 2-BSF is applied to the set input of backspace flip-flop 4-85, the latter flip-flop being reset whenever any of the other modes are initiated.

A specific tape control system has been described and illustrated. This tape control system was illustrated in an embodiment utilizing specific logic circuitry in order to effect the necessary functions. It will be appreciated that those skilled in the art are capable and expected to modify this logic circuitry in accordance with the particular needs of the equipment with which they are working. The scope of the invention is intended to include all modifications that come within the spirit and teachings of this disclosure.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A tape reader and control system comprising gating means controlling the response of the system to the reading of characters on a tape, decoding means operative to detect a character on said tape and provide discrete indications representative of said character, means responsive to said decoding means for enabling said gating means in accordance with the particular character detected; and delay means responsive to the detection of at least one previous predetermined character on said tape for delaying enablement of said gating means in accordance with said previously detected predetermined character.

2. A tape reader control system according to claim 1 wherein said delay means is effective to introduce a long delay in response to detection of at least one previously predetermined character and a short delay in response to detection of at least another one previously detected predetermined character.

3. A tape reader and control system according to claim I, further comprising first and second delay means controlled by said decoding means to effect long or short delays, respectively, before enablement of said gating means and depending upon a plurality of previously detected characters.

4. A tape reader and control system according to claim 3 wherein said first delay means is operative in response to detection of any one of a plurality of nonprintable characters, and said second delay means is operative in response to detection of a given one of said plurality of nonprintable characters only if there has not been a printable character since the detection of the previous given one of a plurality of nonprintable characters.

5. A tape reader and control system according to claim 4 wherein said plurality of characters comprises commands for mechanical operations of connected equipment, and a second plurality of characters comprises commands for printing par ticular characters at said connected equipment, said second delay means being operative in response to detection of a character of said second plurality between the detection of a given one of said plurality of nonprintable characters and the detection of the previous given one of said plurality of nonprintable characters.

6. Apparatus according to claim 1 further comprising means responsive to the detection of at least one subsequently presented predetermined character on said tape for inhibiting the delayed enablement of said gating means in accordance with said at least one previous character detected.

7. Apparatus according to claim 24 wherein said third interval is less than said first or second interval.

8. A tape reader and control system connected to a teleprinter, said tape reader being operative in steps to read printable and nonprintable tape bearing characters for controlling said teleprinter, first means for detecting particular characters requiring nonprinting operations of said teleprinter, control means for automatically advancing the tape in said reader, delay means operative in response to said first means to inhibit operation of said control means for a first period of time sufficient for the carrying out of said nonprinting operations, means for selectively advancing the tape in discrete steps and presenting successive characters for reading at each step, said means being selectively inactivated upon detection of particular characters, and means responsive to detection of a predetermined particular character to inhibit the tape reader from reading at least one printable character subsequently presented.

9. A tape reader and control system according to claim 8 including means for advancing said reader at an accelerated rate during detection of said at least one subsequently presented character.

10. A tape reader and control system according to claim 8 wherein said means is automatically activated upon detection of a preselected character.

11. In a tape reader and control system connected to a teleprinter, said tape reader being operative to advance the tape in discrete increments in response to a signal, each increment placing a successive code on the tape in a reading position, wherein said codes represent printable characters and commands to said teleprinter for printing said characters individually, in words, and in lines; the improvement comprising first means for generating said signal one time, gating means for providing said signal under control of said teleprinter, detecting means for detecting the code appearing in said reading position and providing discrete signal conditions upon each advance of said tape and when said code represents the end of a word or line, means operative to actuate said first means and for selectively blocking said gating means under the control of said discrete signal conditions.

12. In a tape reader and control system according to claim 11 means operative when said gating means is blocked to supply said signals to said reader at a high repetition rate.

13. In a tape reader and control system according to claim ll, means operative to deactivate the tape reader when said detecting means does not provide a discrete signal condition upon and advance of the tape.

14. In a tape reader and control system according to claim 11, means for periodically producing second signals that backspace the tape in discrete increments in response to each signal, said means being operative in response to a signal condition from the teleprinter, means for terminating production of said second signals when a second particular code is in said reading position, and thereafter activating said first means.

15. A tape reader and control system according to claim 14, wherein said second signals are produced at a high repetition rate.

16. A source of information in bit parallel, character serial form, means for providing a first advance signal, means for reading out of said source one character at a time in response to said first advance signal, a printer, means for activating said printer to respond to read characters, said means for providing a first advance signal comprising means to generate a first advance signal for enabling the reading of the next character after the printer response is completed, means responsive to a read character being a printable character for enabling said printer to respond to said read character, means responsive to said read character being one of a plural number of nonprintable characters for enabling said printer to respond to said read, one of a plural number of nonprintable characters and to generate a second advance signal for reading the next character only after a given time delay, said means for reading responsive to said second advance signal in place of said first advance signal to read out the next character.

17. A source of information in bit parallel, character serial form, means for reading out of said source one character at a time in response to a control signal, a printer adapted to be enabled to respond to such read characters, means responsive to a read character being a printable character for. enabling said printer to respond to said read, printable character and to provide a first control signal upon the response being completed, said means for reading responsive to said first control signal for reading the next character after the elapse of a first time period, means responsive to said read character being one of a plural number of nonprintable characters for enabling said printer to respond to said read, one of a plural number of nonprintable characters and to provide a second control signal upon the response being completed, said means for reading responsive to said second control signal for reading the next character only after the elapse of a second time period, said means for readingresponsive to said second control signal in place of said first control signal to read out the next character.

18. A source of information stored on tape in bit parallel, character serial form, a tape reader, means for presenting one character at a time from said source to said reader in response to a control signal, a printer adapted to be enabled to respond to such presented characters, means responsive to a presented character being a printable character for enabling said printer to respond to said presented, printable character and to provide a first control signal upon the response being completed, said reader responsive to said first control signal for reading the next character, means responsive to said presented character being any one of a plural number of nonprintable characters for enabling said printer to respond to said presented, one of a plural number of nonprintable characters and to provide a second control signal upon the response being completed, and said reader responsive to said second control signal for reading the next character only after a given time delay.

19. A source of characters in digital form, means for presenting one character at a time from said source in response to a control signal, a printer adapted to be enabled to respond to such presented characters, means responsive to a presented character being a printable character for enabling said printer to respond to said presented, printable character and to provide a first control signal upon the response being completed, said means for presenting responsive to said first control signal for presenting the next character, means responsive to said presented character being one of a plural number of nonprintable characters for enabling said printer to respond to said presented, one of a plural number of nonprintable characters and to provide a second control signal upon the response being completed, and said means for presenting responsive to said second control signal for presenting the next'character onlyafter the elapse of a given time delay.

20. A tape reader and control system connected to a teleprinter, said tape reader being operative in steps to read tape bearing characters for controlling said teleprinter, first means for detecting particular characters requiring mechanical operations of said teleprinter, control means for automatically advancing the tape in said reader, delay means operative in response to said first means to inhibit operation of said control means for a first period of time sufficient for the carrying out of said mechanical operations, second means for detecting characters requiring printing-by said teleprinter, and second delay means operative in response to said first means and second meanswhen said'mechanical operation is line feed and certain preceding characters did not require printing, said second delay means inhibitingoperation of said control means for a period of time less than said first period.

21. A printer for responding to serially received characters comprising means for responding to a given character, means for delaying said response to said given character for a first time interval in response to at least one predetermined character received prior to said given character, means for delaying said responseto said given character for a second time interval in response to at least a different one predetermined character received prior to said given character, and means for delaying said response to said given character for a time interval different from said first and second time intervals in response to at least one predetermined character received after said given character.

22. Means for sensing in a predetermined sequence printable and nonprintable charactersstored in a storage device, means for reading in said predetermined sequence said sensed characters, to produce electrical signals representative of said sensed characters, means responsive to the reading of at least one particular nonprintable character for initiating a given time delay period, means for sensing and reading in said predetermined sequence nonprintable characters during said time delay period until a printable character is sensed, means responsive to saidlast-named sensed printable character for delaying further sensing and reading of characters until said time delay period has expired, and means for resuming sensing and reading of characters in said predetermined sequence after said time delay period has expired.

23. An arrangement according to claim 22 wherein said at least one nonprintable character comprises a nonprintable character requiring a greater time period for execution than the longest time period between printing of two successive printable characters stored in said storage device.

24. An arrangement according to claim 23 further comprising means responsive to electrical signals representative of printable characters for causing printing thereof and responsive to electrical signals representing nonprintable characters for executing nonprinting functions.

25. Means for serially sensing printable and nonprintable characters stored serially in a storage device, means for reading saidsensed characters at a first rate to produce electrical signals representative of said sensed characters, means responsive to one particular read nonprintable character for delaying reading-of the next following printable character for a given time period but not delaying the reading of all nonprintable characters sensed during said period before said next following printable character, means responsive to asecond particular read nonprintable character immediately following said first-mentioned particular read nonprintable character for reading the next following sensed characters at a second rate as long as such next following sensed characters are said second particular nonprintable characters.

26. Means for serially sensing printable and nonprintable characters stored serially in a storage device, means for reading said sensed characters at a first rate to produce electrical signals representative of said sensed characters, means responsive to at least one of several read nonprintable characters for delaying reading of the next following printable character for a given time period but not delaying the reading of all nonprintable characters sensed during said period before said next following printable character, means responsive to a predetermined one of said several read nonprintable characters immediately following said first-mentioned read nonprintable character for reading the next following sensed characters at a second rate as long as such next following sensed characters are said predetermined one of said several nonprintable characters.

27. An arrangement according to claim 26 wherein said several nonprintable characters comprise a line feed. a carriage return, an escape and a back space and said predetermined one of said several nonprintable characters comprises a line feed.

28. Means for serially sensing printable and nonprintable characters stored serially in a storage device, means for serially reading said sensed characters to produce electrical signals representative of said sensed characters. means responsive to at least one of several read nonprintable characters for delaying reading of the next following printable character for a given time period but not delaying the reading of at least one of predetermined ones of said nonprintable characters sensed duringsaid period before said next following printable character.

l l l

Claims (28)

1. A tape reader and control system comprising gating means controlling the response of the system to the reading of characters on a tape, decoding means operative to detect a character on said tape and provide discrete indications representative of said character, means responsive to said decoding means for enabling said gating means in accordance with the particular character detected; and delay means responsive to the detection of at least one previous predetermined character on said tape for delaying enablement of said gating means in accordance with said previously detected predetermined character.

2. A tape reader control system according to claim 1 wherein said delay means is effective to introduce a long delay in response to detection of at least one previously detected predetermined character and a short delay in response to detection of at least another one previously detected predetermined character.

3. A tape reader and control system according to claim 1, further comprising first and second delay means controlled by said decoding means to effect long or short delays, respectively, before enablement of said gating means and depending upon a plurality of previously detected characters.

4. A tape reader and control system according to claim 3 wherein said first delay means is operative in response to detection of any one of a plurality of nonprintable characters, and said second delay means is operative in response to detection of a given one of said plurality of nonprintable characters only if there has not been a printable character since the detection of the previous given one of a plurality of nonprintable characters.

5. A tape reader and control system according to claim 4 wherein said plurality of characters comprises commands for mechanical operations of connected equipment, and a second plurality of characters comprises commands for printing particular characters at said connected equipment, said second delay means being operative in response to detection of a character of said second plurality between the detection of a given one of said plurality of nonprintable characters and the detection of the previous given one of said plurality of nonprintable characters.

6. Apparatus according to claim 1 further comprising means responsive to the detection of at least one subsequently presented predetermined character on said tape for inhibiting the delayed enablement of said gating means in accordance with said at least one previous character detected.

7. Apparatus according to claim 24 wherein said third interval is less than said first or second interval.

8. A tape reader and control system connected to a teleprinter, said tape reader being operative in steps to read printable and nonprintable tape bearing characters for controlling said teleprinter, first means for detecting particular characters requiring nonprinting operations of said teleprinter, control means for automatically advancing the tape in said reader, delay means operative in response to said first means to inhibit operation of said control means for a first period of time sufficient for the carrying out of said nonprinting operations, means for selectively advancing the tape in discrete steps and presenting successive characters for reading at each step, said means being selectively inactivated upon detection of particular characters, and means responsive to detection of a predetermined particular character to inhibit the tape reader from reading at least one printable character subsequently presented.

9. A tape reader and control system according to claim 8 including means for advancing said reader at an accelerated rate during detection of said at least one subsequently presented character.

10. A tape reader and control system according to claim 8 wherein said means is autOmatically activated upon detection of a preselected character.

11. In a tape reader and control system connected to a teleprinter, said tape reader being operative to advance the tape in discrete increments in response to a signal, each increment placing a successive code on the tape in a reading position, wherein said codes represent printable characters and commands to said teleprinter for printing said characters individually, in words, and in lines; the improvement comprising first means for generating said signal one time, gating means for providing said signal under control of said teleprinter, detecting means for detecting the code appearing in said reading position and providing discrete signal conditions upon each advance of said tape and when said code represents the end of a word or line, means operative to actuate said first means and for selectively blocking said gating means under the control of said discrete signal conditions.

12. In a tape reader and control system according to claim 11 means operative when said gating means is blocked to supply said signals to said reader at a high repetition rate.

13. In a tape reader and control system according to claim 11, means operative to deactivate the tape reader when said detecting means does not provide a discrete signal condition upon an advance of the tape.

14. In a tape reader and control system according to claim 11, means for periodically producing second signals that backspace the tape in discrete increments in response to each signal, said means being operative in response to a signal condition from the teleprinter, means for terminating production of said second signals when a second particular code is in said reading position, and thereafter activating said first means.

15. A tape reader and control system according to claim 14, wherein said second signals are produced at a high repetition rate.

16. A source of information in bit parallel, character serial form, means for providing a first advance signal, means for reading out of said source one character at a time in response to said first advance signal, a printer, means for activating said printer to respond to read characters, said means for providing a first advance signal comprising means to generate a first advance signal for enabling the reading of the next character after the printer response is completed, means responsive to a read character being a printable character for enabling said printer to respond to said read character, means responsive to said read character being one of a plural number of nonprintable characters for enabling said printer to respond to said read, one of a plural number of nonprintable characters and to generate a second advance signal for reading the next character only after a given time delay, said means for reading responsive to said second advance signal in place of said first advance signal to read out the next character.

17. A source of information in bit parallel, character serial form, means for reading out of said source one character at a time in response to a control signal, a printer adapted to be enabled to respond to such read characters, means responsive to a read character being a printable character for enabling said printer to respond to said read, printable character and to provide a first control signal upon the response being completed, said means for reading responsive to said first control signal for reading the next character after the elapse of a first time period, means responsive to said read character being one of a plural number of nonprintable characters for enabling said printer to respond to said read, one of a plural number of nonprintable characters and to provide a second control signal upon the response being completed, said means for reading responsive to said second control signal for reading the next character only after the elapse of a second time period, said means for reading responsive to said second control signal in place of said first control signal to read out the next character.

18. A source of information stored on tape in bit parallel, character serial form, a tape reader, means for presenting one character at a time from said source to said reader in response to a control signal, a printer adapted to be enabled to respond to such presented characters, means responsive to a presented character being a printable character for enabling said printer to respond to said presented, printable character and to provide a first control signal upon the response being completed, said reader responsive to said first control signal for reading the next character, means responsive to said presented character being any one of a plural number of nonprintable characters for enabling said printer to respond to said presented, one of a plural number of nonprintable characters and to provide a second control signal upon the response being completed, and said reader responsive to said second control signal for reading the next character only after a given time delay.

19. A source of characters in digital form, means for presenting one character at a time from said source in response to a control signal, a printer adapted to be enabled to respond to such presented characters, means responsive to a presented character being a printable character for enabling said printer to respond to said presented, printable character and to provide a first control signal upon the response being completed, said means for presenting responsive to said first control signal for presenting the next character, means responsive to said presented character being one of a plural number of nonprintable characters for enabling said printer to respond to said presented, one of a plural number of nonprintable characters and to provide a second control signal upon the response being completed, and said means for presenting responsive to said second control signal for presenting the next character only after the elapse of a given time delay.

20. A tape reader and control system connected to a teleprinter, said tape reader being operative in steps to read tape bearing characters for controlling said teleprinter, first means for detecting particular characters requiring mechanical operations of said teleprinter, control means for automatically advancing the tape in said reader, delay means operative in response to said first means to inhibit operation of said control means for a first period of time sufficient for the carrying out of said mechanical operations, second means for detecting characters requiring printing by said teleprinter, and second delay means operative in response to said first means and second means when said mechanical operation is line feed and certain preceding characters did not require printing, said second delay means inhibiting operation of said control means for a period of time less than said first period.

21. A printer for responding to serially received characters comprising means for responding to a given character, means for delaying said response to said given character for a first time interval in response to at least one predetermined character received prior to said given character, means for delaying said response to said given character for a second time interval in response to at least a different one predetermined character received prior to said given character, and means for delaying said response to said given character for a time interval different from said first and second time intervals in response to at least one predetermined character received after said given character.

22. Means for sensing in a predetermined sequence printable and nonprintable characters stored in a storage device, means for reading in said predetermined sequence said sensed characters to produce electrical signals representative of said sensed characters, means responsive to the reading of at least one particular nonprintable character for initiating a given time delay period, means for sensing and reading in said predetermined sequence nonprinTable characters during said time delay period until a printable character is sensed, means responsive to said last-named sensed printable character for delaying further sensing and reading of characters until said time delay period has expired, and means for resuming sensing and reading of characters in said predetermined sequence after said time delay period has expired.

23. An arrangement according to claim 22 wherein said at least one nonprintable character comprises a nonprintable character requiring a greater time period for execution than the longest time period between printing of two successive printable characters stored in said storage device.

24. An arrangement according to claim 23 further comprising means responsive to electrical signals representative of printable characters for causing printing thereof and responsive to electrical signals representing nonprintable characters for executing nonprinting functions.

25. Means for serially sensing printable and nonprintable characters stored serially in a storage device, means for reading said sensed characters at a first rate to produce electrical signals representative of said sensed characters, means responsive to one particular read nonprintable character for delaying reading of the next following printable character for a given time period but not delaying the reading of all nonprintable characters sensed during said period before said next following printable character, means responsive to a second particular read nonprintable character immediately following said first-mentioned particular read nonprintable character for reading the next following sensed characters at a second rate as long as such next following sensed characters are said second particular nonprintable characters.

26. Means for serially sensing printable and nonprintable characters stored serially in a storage device, means for reading said sensed characters at a first rate to produce electrical signals representative of said sensed characters, means responsive to at least one of several read nonprintable characters for delaying reading of the next following printable character for a given time period but not delaying the reading of all nonprintable characters sensed during said period before said next following printable character, means responsive to a predetermined one of said several read nonprintable characters immediately following said first-mentioned read nonprintable character for reading the next following sensed characters at a second rate as long as such next following sensed characters are said predetermined one of said several nonprintable characters.

27. An arrangement according to claim 26 wherein said several nonprintable characters comprise a line feed, a carriage return, an escape and a back space and said predetermined one of said several nonprintable characters comprises a line feed.

28. Means for serially sensing printable and nonprintable characters stored serially in a storage device, means for serially reading said sensed characters to produce electrical signals representative of said sensed characters, means responsive to at least one of several read nonprintable characters for delaying reading of the next following printable character for a given time period but not delaying the reading of at least one of predetermined ones of said nonprintable characters sensed during said period before said next following printable character.

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