FR2575848A1 - Device for teaching functions carried out by a microprocessor - Google Patents

Abstract

The invention relates to a device making it possible to facilitate understanding of the main functions carried out by a microprocessor. It is constituted by cards: clock 1, control memory 2, programme memory 3, arithmetic and logic unit 4, data memory 5, interface 6, microprocessor 7 and by a power supply 8, mounted on a support 9. The association of some of these cards on a connector cable 10 makes it possible to study all or part of the functions of the calculator and to compare the carrying out of similar functions by specific function cards 2, 3, 4 and by a microprocessor card 7. The transfer mechanisms and the data transferred are displayed 12. Buttons 11 make it possible to act on the device and to cause it to execute step by step or dynamically a programme which is loaded into its memory. The device according to the invention is particularly intended to be used in general computing courses.

Description

 The present invention relates to a teaching tool used to concretize the main functions performed by a microprocessor.

 The teaching of these functions is traditionally carried out on the basis of the student's prior knowledge or by a preliminary study of elementary parcel or theoretical circuits supplemented by a theoretical presentation of the technical characteristics provided by a manufacturer of microprocessor.

 A study of examples, a use of an existing microprocessor, the production of an application can complete the training cycle.

 With this method or the various stages relate to circuits not connected to each other or to professional equipment not specified for the problem, the global vision, for example the interaction between a program and the material running it, can only be long and difficult to obtain by a neophyte.

 The device according to the invention makes it possible to shorten and facilitate the understanding of the functions performed by a microprocessor.

 These results are obtained by integrating the simplest possible possible basic functions in functionally linked electronic cards which can be studied, theory and practice, progressively individually then globally until forming a computer executing a program. simple.

the explanation of the functions of a microprocessor is obtained by analogy of operation between cards with specific tones (2), (3), (4) and a microprocessor card (7)
This analogy is obtained by replacing the specific cards with the microprocessor card, Ze remains of the device remaining unchanged.

 In both cases the program respects the same analysis conditions and can be studied step by step or dynamically.

 A program change can be done by changing the circuits where they are permanently stored.

 The exchange mechanism and the information exchanged by the various elements of the system are constantly displayed.

 The main partial functions to be studied using the buttons and indicators of the device are: writing reading in RAM, reading permanent memories, performing arithmetic and logic operations.

 An instruction manual groups together by chapters all of the theoretical summaries, exercises and practical work to be performed on each card or each function or on the programs executed by the device.

 Figure I shows the overview of the device.

 This figure is used for the abstract.

 Figure 2 shows all the buttons and indicators.

 FIG. 3 represents the electrical circuit of the clock (I) and control memory (2) cards.

 FIG. 4 represents the electrical circuit of the program memory cards (3) and arithmetic and logic unit (4).

 FIG. 5 represents the electrical circuit of the data memory cards (5) - and interface (6).

 FIG. 6 represents the electrical circuit of the microprocessor card (7).

 Figure I shows how the cards (I), (2), (3), (4), (5) (6) and (7) can be, depending on the function to be performed, connected to the connectors of a flat cable (I0) and supplied (8).

the entire device rests on a support (9).

Figure 2 adds to Figure I the vision of the buttons and indicators: - microinstruction advance (I4) - visualization advances one step (I5) - program start or stop (I6) - automatic or manual step (I7) reading of permanent memories (I8) -resetting the pulse flip-flop (19) -pulse visualization (20) -specific microsignal visualization (21) -visualization of destination signals (22) -visualization of source signals (23) -visualization of the addresses of microinstructions (24) -visualization of instruction addresses (25) -visualization of the instruction code (26) -visualization of the parameter part of the instruction (27) -visualization of the jump condition (28) -visualization of the operation code (29) - operation code validation (30) -visualization of the contents of register A (31) -increment information in register A (32) -visualization of the contents of register B (33) -loading of information in register B - (34) -visualisation address of the variable (35) -cha change of the address of the variable (36) -visualization of signals D3 and S2 (37) -visualization of the variables (38) -visualization validation (39) -loading of a variable in the input register (40) -visualization write validation (41) -write validation (42) -program interface buttons (43) -visualization of SI and DI signals (44) -program interface lights (45) -visualization of logic levels (46)
The other components (integrated circuits, resistors, capacitors, etc.) are not shown on the cards in FIG. 2.

 FIG. 3 represents the clock function and the control memory function.

 The clock includes a stable mono (47) providing pulses with an adjustable period.

 the shift circuit (48) makes it possible to create pulses incrementing the pointer register (4) of the control memory (50). It also generates the synchronization pulses yes are distributed to the whole of the device (51).

 When the inverter (I7) is in its "manual" position, a button on the push button (I4) initializes each basic period and makes it possible to run a program step by step.

 In its closed position, an inverter (I6) keeps the registers at zero and pockets the progress of the programs.

their triggering is obtained by opening this inverter (16).

 The button (18) allows step-by-step reading of the control memory (50) and the program memory (53). Word-by-word advancement is achieved by pressing the push button (14).

The control memory part contains: a pointer register (49), a control memory (50) made up of three components
permanent memory, decoders (52) and display circuits
alisation (21), (22), (23), (24) showing the addresses of
microinstructions and the signals generated each microins
truction.

The memory contains the eight basic instructions specifi-
to the device. They have a maximum of four microins
for each one a mnemonic is used.

 -EMD, ADR write to memory at address ADR.

 -LMD, ADR. Read a word from the data memory.

 -OAL, X arithmetic or logical operation specified by X.

 -CST, X write a constant X in the register a.

 -JUMP, X. Jump to program address X.

 -SCOND, X. Conditional jump to program address X.

 -LEX. Read an external word entered on the buttons (43).

 -AFF. Display of a word on the indicators (45).

 Figure 4 shows the program memory and arithmetic and logic unit functions.

 The memory part is organized around the program memory (53) yes is made up of a permanent memory component making it possible to store 256 instructions defined according to the 7th set of the eight basic instructions.

 Each machine instruction has a code part displayed on the indicators (26) and a parameter X part displayed on the indicators (27).

 If X is a program address it can be loaded into the pointer (54).

 A program change is obtained by changing the memory components (53).

 A set of logic gates (55) make it possible to define whether to increase the pointer (54) or load it with an address specified in the parameter of the instruction.

 The instruction code (56) is used to address the control memory (56), (50).

 The electrical circuit of the arithmetic and logic unit card is organized around the arithmetic and logic function (57).

 The code of the operation to be performed comes from the parameter of the program instruction and is loaded into the code register (58).

 The operations are carried out on words of eight digits coming from the registers "A" (59) and "B" (60).

 The registers "code", "A", "B" can be loaded manually using the buttons on the interface card (43) and the validation buttons (30), (32), (34).

 In automatic operation a "H2" signal (61) is present and allows the arrival of the destination signals (62) coming from the control memory (50).

 When all the digits of the result are logical, the flip-flop "condition" (63) is set to one.

 This defines the conditional jump condition for programs.

 Figure 5 shows the circuits of. cards. data memory (5) and interface (6).

 The memory (64) is a static random access memory which stores the variables used by the programs.

 It is addressed by the register (65).

 The register (66) is used for data entry, the register (67) for data output.

 The buttons (36), (40), (42) are used for manual operations on this card.

 Destination signals (68), (69).

 Write validation signal (70).

 FIG. 5 in its interface part represents: the DC power supply part (7I), the data entry doors (72), the flip-flops (73) and the amplifiers (74) for outputting data on the indicator lights (45).

 The circuit (75) creates the signal "H2" if the clock card is present on the cable (10).

"H2" (61) synchronizes the cards (4) and (5) from the synchronization signal supplied by the shift register (48) of the clock card (I).

 FIG. 6 represents the electrical circuit of the microprocessor card (7).

 If a memory validation signal (77) is present, the addresses (78) that the microprocessor (76) generates are sent to the counter (79) of the new program memory (80) or to the data memory card (5) (point 8I).

 This depends on the most significant address digit: equal to zero, the signal (82) validates the parallel input of the counter (79), equal to one, a validation signal is sent to the data memory card ( 5) to validate the parallel input of its address counter (65).

 The signals (83) and (84) specify whether it is a read or a write. As the case may be, the destination and write validation signals will not have the same values (85), (86), (87), (88).

 They arrive at (68), (69), (87) and (88) in the data memory. Figure 5.

 The microprocessor (76) is connected to the data transfer link (89). Likewise, through three-state diodes (90), for the program memory (80).

 An input / output interface validation signal (91) allows the decoding (92) of the address digits of weight the most fable and venerate signals of destination towards the rockers (73) or of source towards the doors ( 72) of the interface card (6).

 The signal (3) is the clock signal. It comes from the shift register (48) of the clock card (I).

 The signals (94) usually used to allow "direct memory access" are not used here.

 A circuit (95) generates a reset signal and an interruption when the user uses the program start button (I6) on the card (I). This interruption directs the microprocessor (76) to the first instruction in the program. stored in memory (80).

 Indicators (6) display addresses, program instructions, validation signals.

The teaching of the functions performed by a microprocessor using the device according to the invention is done in stages:
step I: introduction to the concept of logical level.

 The interface card (6) is the only one connected to the flat cable.

 Step 2: introduction to the notions of memorization, binary words and addressing using the interface card (6) to write in data memory (64).

 Step 3: introduction to Boolean algebra. Carrying out arithuetic and logical operations with the help of the buttons on the interface card by the card (4).

 Step 4: permanent memory and introduction to the concept of microprograms, microinstructions, machine instructions.

 the program memory cards (3) and microprocessor (7) are the only cards not connected on the flat cable.

 The memory read button (18) of the clock card is in the button read position (I6) in the "program on" position, successive presses on the button (I4) increment the counter (4) in the control memory and allow to visualize microinstruction by microinstruction the signals it generates.

 The cards where they are used being present, one obtains a concretization of the action sought by each of the eight basic machine instructions.

 i; step 5: concept of program. The clock (I), Drogramme memory (3) and interface (6) cards are the only ones connected to the flat cable.

 Button (16) on "program run". Button (18) on "read memory".

 Successive presses on the increment button (I4) make it possible to read, instruction by instruction, the proora stored in memory (53) and compare it with the analysis and programming documents included in the manual.

 Step 6: all cards are plugged into the cable except the microprocessor card (7). The button (I7) is on "manual".

 Successive actions on 1 increment button (I4) allow to concretize, instruction by instruction, the action of the program on the whole device.

 Step 7: same as step 6, except that the button (I7) is in its "automatic" position, the program runs at normal speed.

 Step 8: same as in 6 (step by step operation) but by having the microinstruction functions, arithmetic and logic unit, carried out by a microprocessor.

 The cards (2), (3), (4) are not connected, the microprocessor card (T) replaces them.

 Step 8 is the first example of using an assembly language specific to a microprocessor.

 A change in the program stored in the memory (80) makes it possible to extend this study of assembly language.

 Step 9: generalization to other aspects of using a microprocessor. Normal program speed.

 Multiple interruptions, direct memory access.

 A card, not shown in the figures, containing a parallel interface device and serial interface completes the general device.

 This part of the description highlights some points of the practical implementation of the device.

 Electronic cards are made from double-sided printed circuits measuring ten by twenty centimeters.

 They are pluggable, without the use of any tools, on flat cable connectors "3M" (registered trademark).

 The "indicators" mentioned in the rest of the text are, in fact, individual or grouped light-emitting diodes.

 The diodes and buttons are directly mounted on the upper part of the cards so as to allow easy use of the device.

 Self-adhesive labels specify the function of the diode or button.

 The support (9) is preferably produced by two pieces of aluminum profiles twenty-five inches long. The connectors of the flat cable (IO) are screwed onto these profiles and thereby give rigidity to the entire support.

 The power supply has its current part redesigned (71) on the interface card (6). The transformer is located in a box (8) fixed on one of the profiles. This box also contains a fuse, an on / off button, a female socket for connection of a power cord.

 the electronic cards can be connected in any order on the flat cable.

The flat cable contains fifty wires carrying the signals:
<100) -8 wires of data transfer.

 (81) -8 address wires from the data memory.

 (101) -increment of the counter (49) of the control memory.

 (I02) -resetting of registers and counters.

 (I03) - end of sequence micro-signal. Each basic instruction consists of a sequence of up to four micrå- instructions.

(I04) -specific micro-signals including: S (jump),
SC (conditional jump), EM (memory write validation), +1 (instruction increment).

 (105) -four source micro-signals, SI to S4, each validating the connection on the data link of one of the original components containing the information to be transferred to a destination component.

 (I06) -seven signals, DI to D7, validating the "destination" component, which receives the data to be transferred.

 (I07) -zero Aogique.Signal created by the clock card (I) and sent to the interface card (6) allowing it to generate the synchronization signal (61) for global operation.

 (108) - memory read signal. It prohibits program jumps and does not leave the possibility of incrementing the counters (49) and (54) for word-by-word reading of the memories.

 (56) -other signals from the operating code. This code is part of the instruction and it defines it.

 I1 is used as the starting address of each basic sequence by the counter (49) of the control memory.

This counter has its two least significant address wires kept at zero and the code arrives on the following four: an address equal to four times the code is obtained, which allows a maximum of four microinstructions in each sequence
(109) -signal of presence of the microprocessor card (7).

This signal closes the doors which connect the data wires (100) to the address wires (81) of the register (65) of the data memory.

 This connection is used by operation with specific cards (2), (3), (4) to load the address into the register (65) from the data wires.

 The source, destination, write validation signals (85r, (86), (87), (88) created by the microprocessor card (7) use the wires left free by the signals (105), (106) not present.

the card (2) cannot be present at the same time as the card (7).

 The analysis flowcharts, the assembler and machine instruction lists are not mentioned in this descriptive text (not patentable).

 The device according to the invention is particularly intended to be sold to all persons and communities concerned with teaching the functions and the use of a microprocessor in a digital logic system.

Claims (10)

 1) Device for teaching functions performed by a microprocessor composed of electronic cards, a power supply (71), a connector cable (10), all mounted on a support (9) and characterized by a clock card (1), a control memory card (2), a program memory card (3), an arithmetic and logic unit card (4), a data memory card (5), an interface card (6), a card- micro-processor (7) which, progressively connected to the cable (10), can operate in successive independent sets until forming, in the final phase, a teaching computer.  2) Device according to claim I characterized by its ability to execute a program responding to the same analyst either with cards with specific functions (2), (3), (4) or with a microprocessor card (7), the cards (1), (5), (6) being common to the two operating cases.  3) Device according to claims I and 2 characterized in a display of the mechanism of exchanges and information exchanged by its various elements.  4) Device according to claims I and 2 characterized in that it can execute a Drogram normally or with stop after each microinstruction, the transition to the next microinstruction being conditioned by pressing a button (I6).  5) Device according to claim I characterized in that only the presence of cards (4), (5), (6) on the flat cable (IO) is sufficient to perform manually using the buttons (43) of the interface card (6) for read-write operations in data memory (64) and arithmetic and logic operations in the card (4).  6) Device according to claims I and -2 characterized in that the permanent memories (53) and (80) can be read manually and word for word with the buttons on the card (I),  7) Device according to claims 1 and 2 characterized in that a program change is made by changing the components of the memories where they are stored.  8) Device according to any one of claims I to 6 characterized in that the interface between the user and the device is done with indicator lights and buttons.  9) Device according to any one of the preceding claims, characterized in that a book groups together the work to be carried out on each card or each function or on the programs executed by the entire device.  10) Device according to claim 1 characterized by a parallel and serial interface card which completes it.