JPS6083141A - Microprocessor - Google Patents

Abstract

PURPOSE:To attain execution of plural instruction sets by using a read-only control memory part and a read/write control memory part. CONSTITUTION:Control signals 10 and 18 are delivered properly with a multiplexer 14 set at the side of a read-only control memory part 1. Thus it is possible to write the information given from outside to a read/write control memory part 11. If a microprogram is incorporated to the part 1 to switch the multiplexer 14 toward the part 11 after reading the information given from outside and writing it to the part 11, a microprocessor works with the information read from outside used as the control memory. Then said information is changed properly to be different is action even through an instruction register 3 has the same contents.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microprocessor in the form of a microprogram having an internal control memory. Conventionally, the control memory of a microprocessor was stored in a read-only memory, so the contents were fixed; A microprocessor could only perform one specific operation based on instructions given from the outside.

FIG. 1 is an internal block diagram showing an example of the configuration of a conventional microprocessor with built-in control memory.

1 is a control storage unit, 2 is a microprogram control circuit,
3 is an instruction register that holds instructions given from the outside;
4 is an address register that holds address information to be outputted to the outside, 5 is a register group, and 6 is an arithmetic circuit.

The control circuit 2 first reads 1 instruction from an external device,
In order to operate the microprogram for storing all instructions in the instruction register 3, the instruction address information 8t is outputted to the microphone. The control signal lO, which is the output of the control storage unit l, is appropriately outputted by the microprogram and stores the instructions read from the outside into the instruction register 3.
Thereafter, the control circuit 2 sets certain microinstruction address information 8 for each instruction held in the instruction register 3.
and performs each instruction while appropriately controlling the register group 5, arithmetic circuit 6, etc. In this case, for a certain instruction, the microinstruction address information 8 output from the control circuit 2 is constant sb, and the contents of the control memory 1 are also fixed, so
A microprocessor's behavior for a single instruction,
It becomes something fixed. For this reason, conventional microprocessors have the disadvantage that they can only execute one fixed set of instructions and cannot use programs of different models.

The object of the present invention is to eliminate such drawbacks and to provide a complete microprocessor capable of executing multiple instructions. To achieve this object, the microprocessor according to the invention has a read-only control memory. and nine control storage parts that allow both reading and writing, and this reading,
It is constructed by providing a means for transferring information from the outside to a writable control storage section.

Next, the present invention will be explained in more detail with reference to the drawings. Fig. 2 is an internal partial block diagram showing an embodiment of the microprocessor of the present invention, ] is a read-only control storage section, 2 is a microprogram control circuit, and 3 is an instruction read from the outside. An instruction register 11 holding the data is a readable and writable control storage section and is also connected to the data bus 9. 12 is a counter for giving address information when writing information to the control storage unit 11;
13 is a multiplexer for switching between the output 15 of the counter 12 and the microinstruction address information output from the control circuit 2; Output 16
The output 17'e of the control storage section 11 is switched by the output signal 19 of the control circuit 2 by a multiplexer for switching, and is transmitted to the control signal 18 and the control signal IO. Other parts are similar to the conventional microprocessor shown in FIG.

With such a configuration, it is possible to write information from the outside into the control storage section 11 by appropriately outputting the control signals 10 and 18 with the multiplexer [4] set to the control storage section l side. becomes. In the microprocessor configured as described above, the control memory section 1 is configured to read information from the outside, write it to the control memory section 1, and then switch the multiplexer 14 to the control memory section 11 side. If a microprogram is constructed, the microprocessor will not operate using the information read from the outside as control memory, and by appropriately changing the information given from the outside, the contents of the instruction register 3 can be kept the same. However, it is possible to perform different operations. Also, if you want to write control memory during program execution, you can provide a microprogram that operates the control memory section l from the outside in advance.

[Brief explanation of the drawing]

Figure 1 is an internal block diagram of a conventional microprocessor.
FIG. 2 is an internal block diagram according to an embodiment of the present invention. ◎ 1... Read-only control storage section, 2...
・Microprogram control circuit, 3...Instruction register, 4...Address register, 5...
...Register group, 6... Arithmetic circuit, 7...
...Instruction register output signal, 8...Microinstruction address information, 9...Data bus, 10...
... Control signal, 11. Song, read, writable control storage section, 12. Group, counter, 13.14.
...Multiplexer, 15...Write address information, 16.17...Group control memory output, 18.
...Write signal, 19...Control storage unit l side signal, 20...Multiplexer output. h f figwa? figure

Claims (1)

[Claims] A microprocessor comprising: a read-only control memory; a readable and writable control memory; and means for externally transferring information to the readable and writable control memory.