JPS60171537A - Microprogram controller - Google Patents

Abstract

PURPOSE:To change quickly and easily the contents of a microprogram by providing an RAM which can store the microprogram to be changed among those stored in a PROM. CONSTITUTION:When a change is needed to the contents of a microprogram MP1, a selector 21 is set under a B input selection state by a selection signal SL1. Then a write control signal WT is set active to write a microprogram MP2 to be changed to an RAM20 with an address AD2 corresponding to an address to be changed of a PROM10. Then the selector 21 is set again under an A input selection state by the signal SL1, and the reading of the stored MP2 is started to the RAM20. Thus a selector 30 is set automatically under a B input selection state by a selection signal SL2. Therefore the programs are executed successively according to the MP2 stored in the RAM20.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a microprogram control device for an information processing device, and specifically relates to an embodiment of a device that can quickly and easily change the contents of the microprogram. Regarding.

[Prior art]

Generally, the above-mentioned microprogram control device uses FROM (programmable read only memory) as a program memory to store the program, and the microprogram stored in the FROM is executed by a microprogram execution circuit. In order to call the next microprogram to be executed based on the execution program in the execution circuit, the FROM is accessed using the output of the execution circuit, thereby realizing sequential and smooth microprogram control.

[Problems with the Prior Art] As described above, by using FROM as the program memory, it has become easier to set up and maintain microprograms, but if a bug occurs in the FROM, , 1) Due to this exchange, execution of the above-mentioned microprogram and its control must be interrupted for a long time.

2) The same FROM is an EPRO whose program can be rewritten.
Even if it is something like M, it will take a considerable amount of time to change the program at this time, and the above-mentioned execution command and control of the microprogram will have to be interrupted during this time.

This resulted in inconveniences such as:

[Purpose of the invention]

The present invention provides a microprocessor that can immediately execute and control the above-mentioned microprograms in accordance with the changed contents without interrupting the execution and control of the above-mentioned microprograms even if it becomes necessary to change the contents of the programs stored in the FROM. The purpose is to provide a program control device.

[Structure of the invention]

In this invention, in addition to the above FROM as a program memory, an arbitrary micro program (the above FROM) can be temporarily used as a program memory.
A RAM (Random Access Memory) capable of storing a desired program for changing the microprogram stored in M is prepared, and an appropriate external writing means for writing the above-mentioned arbitrary microprogram into this RAM; and a second memory which selectively adds either one of the address designated by the writing means and the address designated from the microprogram execution circuit described above to the RAM based on a predetermined selection signal issued by the writing means. 1 selector, and this RAM while reading the microprogram.
Selectively add the program read from M to the microprogram execution circuit, and otherwise
An M2 selector is provided for selectively adding the program read from the OM to the microprogram execution circuit, and if necessary, the RAM prepared above is
A desired microprogram can be freely written into the microprogram, and the written microprogram can be freely executed by the microprogram execution circuit.

〔Effect of the invention〕

Therefore, according to the microprogram control device according to the present invention, even if it becomes necessary to change the program contents stored in the FROM, it is possible to easily and quickly cope with the change by using the RAM. The above objectives can be achieved.

〔Example〕

The figure shows an embodiment of a microprogram control device according to the present invention.

As shown in the figure, this embodiment device has two memories, FROMI O and RAM 20, as program memories, and the above-mentioned FR
Microprogram MPI read from OMIO,
Alternatively, one of the microprograms MP2 read from the RAM 20 is latched by the latch circuit 40 and further added to the microprogram execution circuit 50.

Here, the selector 30 is a circuit that executes the selection operation described above based on the selection signal SL2 that is active while the RAM 20 is in the reading state of the microprogram MP2, and the selection signal SL,2 is inactive. During a certain period of time, it operates to selectively output the microprogram MP1 read from the A input, ie, FROMIO, and while the selection signal SL2 is active, it operates to selectively output the microprogram MP2, which is read from the B input, ie, the RAM 20. In other words, this selector 30
0 is a circuit that selectively outputs the microprogram MP2 with priority while it is being read.

Furthermore, when the microprogram execution circuit 5o executes the microprogram MPI or MP2 selected by the selector 30 and latched by the latch circuit 40, it also executes a microprogram to be executed next based on the execution program. FR above to call
This is a circuit for accessing OMI O or RAM 20, and in this embodiment, the address signal ADI for accessing is the circuit for accessing the FROMI O, as shown in the figure.
0 and the selector 21, respectively.

This selector 21 receives either an address signal AD2 (B input) applied from an external writing device (not shown) via an external switch circuit 22, or an address signal ADI (A input) applied from the microprogram execution circuit 50. One side is also connected to the above external switch circuit 2.
This is a circuit that selects and outputs an address signal based on a selection signal SLI applied from the outside via SLI, and this selectively output address signal is applied to the RAM 20.

The external switch circuit 22 is connected to an external writing device (not shown) as described above, and receives the address signal AD2.
, and the selection signal SL1, and the RARj20
This circuit arbitrarily opens and closes the microprogram MP2 to be stored in the microprogram MP2 and the write control signal WT.

Next, the usage of this example device and an example of operation based on the usage will be explained.

FROMIQ is a program memory in which a predetermined microprogram MP1 is stored in advance, and RAM20 is a program memory in which a program desired to change the microprogram MPI, that is, a microprogram MP2, is stored as necessary.

For example, if the RAM 20 is now empty, that is, the microprogram MP2 has not yet been written, and the selector 21 is in the A input selection state, the selector 30 will automatically be in the A input selection state. Therefore, the device of this embodiment functions to sequentially execute the microprograms MPI stored in the FROMI Q in advance. That is, the loop shown in the figure is PROMI O→selector 30→latch circuit 40→microprogram execution circuit 50→FROMI O, and performs well-known processes such as execution of the microprogram MPI and reading of the next program based on the execution program. Perform the action repeatedly.

During this operation, if it becomes necessary to change the contents of the microprogram MP1, a desired microprogram MP2 is written into the RAM 20 through the external switch circuit 22. That is, in this case,
The selector 21 is set to the B input selection state by the selection signal 8Ll, and the write control signal WT is activated to write the microprogram MP2 to be changed into the RAM 20 with the address AD2 corresponding to the address desired to be changed in the FROMI Q.

Thereafter, when the selector 21 is again set to the A input selection state by the selection signal SLI and reading of the stored microprogram MP2 is started from the RAM 20, the selector 30 is automatically set to ζj'- by the selection signal SL2 as described above. Since it is in the B-manual selection state, the apparatus of this embodiment functions to sequentially execute the microprogram MP2 stored in the RAM 20. That is, the loop shown in the figure is RAM 20 → selector 30 → latch circuit 40 → microprogram execution circuit 50 → selector 21 → RAM 20, and the same operations as described above, such as execution of the microprogram MP2 and reading of the next program based on the execution program, are performed. Perform the action repeatedly.

Incidentally, when the execution of this microprogram MP2 is completed, that is, when the execution of the program related to the changed part is completed, the reading operation of the microprogram MP2 from the RAM2Qiζ has already been completed, and the selector 30 is in the A input selection state. It automatically returns to FR
The corresponding microprogram M from the address next to the address corresponding to the changed program in OM and lQ.
The PIs will be sequentially read and executed.

Thus, according to the device of this embodiment, program changes can be easily and quickly achieved. In addition, in this embodiment device, the microprogram MP2 is written into the RAM 20 and simultaneously read out.
Program to be changed (micro program MP
You can also check the functionality of 2).

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the microprogram control device according to the present invention. 1G-FROM, 20-RAM, 21.30...Selector, 22...External switch circuit, 4o...Latch circuit, 50...Microprogram interception circuit.

Claims (1)

[Claims] a program memory in which microprograms are stored;
a microprogram execution circuit that sequentially executes the microprograms and accesses the program memory to call a microprogram to be executed next based on the execution program; FROM, which is one of the memories and in which a first microprogram is stored in advance; and a FROM, which is also one of the program memories, and in which a second microprogram different from the first microprogram is temporarily stored. RAM, external writing means for writing the second microprogram into the RAM, and an address specified by the external writing means and from the microprogram execution circuit based on a selection signal output from the external writing means. a first selector that selectively adds one of the designated addresses to the RAM; and a second microprogram selector that selectively adds one of the specified addresses to the RAM; selective ζζ the microprogram depth circuit I; and a second selector configured to selectively add the first microprogram, which would otherwise be read from the FROM, to the microprogram execution circuit. A microprogram control device characterized by: