JPH0310323A - Microprocessor - Google Patents

Abstract

PURPOSE:To extend an instruction without producing a chip again by rewriting a part of contents of a control memory in a microprocessor from the outside of the microprocessor and providing an instruction code which issues contents of this rewritten part as a control signal. CONSTITUTION:A control memory address generating part generates a micro address, by which the micro instruction outputted from an EEPROM 23 is selected by selectors 25a to 25c and is outputted to a micro instruction register 13, for a specific instruction code. Micro instruction in the EEPROM 23 are rewritten to generate arbitrary control signals 5a to 5c for this instruction code, and an arbitrary arithmetic processing is performed. The micro address of rewrite is set to a control memory address register 12, and the micro instruction is set to a micro instruction input register 21, and a write signal 20 is applied to the EEPROM 23, thereby rewriting the micro instruction in the EEPROM 23. Thus, the instruction is changed or extended without producing the whole of the chip again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microprocessor, and more particularly to a microprocessor whose instructions can be easily expanded.

[Conventional technology]

FIG. 4 is a diagram showing a block configuration of a conventional microprogram control type microprocessor.

In Figure 4, (6) and (7) are the data bus, address bus, and register section (2) in the microprocessor, respectively.
) is a part consisting of multiple registers in which data to be processed by the microprocessor is stored.
It is possible to input a value into the register section (2) and output the value of the register section (2) to the outside of the microprocessor. The arithmetic processing unit (3) is a part that performs arithmetic processing on the data in the register unit (2), and the instruction register (4) stores coded instructions that specify the type of arithmetic processing to be executed by the microprocessor. It is a register. This instruction code is read from outside the microprocessor through the data port (9). The control circuit section signal) outputs control signals (5a) e (5b), (50) for controlling the register to be subjected to arithmetic processing, the type of operation, etc. according to the instruction code αO in the instruction register (4). This is the part that occurs.

@Figure 5 is a block diagram showing the internal configuration of the control circuit section (]) in Figure 4.

In FIG. 5, the instruction register (4) is a register in which the code of the instruction executed by the microprocessor is stored as described above.0 control memory αC is a read-only semiconductor memory 1:a ff4j (hereinafter referred to as 1 (referred to as OM).This control memory αC contains data (hereinafter referred to as microinstructions) in which each bit corresponds to each control signal (5,), (5b), (50). The micro-instruction in the 0 control memory aD in which the 0 micro-instruction is stored is read from the address pointed to by the control memory address register (6) (hereinafter referred to as the micro-address) and stored in the micro-instruction register α9. Each bit of microinstruction register 0& is each control signal (5a) +
' (5b) and (5C) are sent to each part within the microprocessor. Control memory address generator α
In 4J, a micro address signal is generated based on instruction code 00 or some bits (5d) of micro instruction register α9, and control memory address register (2) is generated.
Store in.

Next, the operation when this microprocessor executes an addition instruction will be explained. First, a code indicating an addition instruction is stored in the instruction register (4) through the data port (9).The zero-order control memory address generation unit α4 generates control for executing the addition instruction based on this instruction code. (ri
A micro-address Q51 in which a micro-instruction corresponding to the number is stored is generated, and this is stored in control memory address register 0.

Next, the microinstruction stored at this microaddress is read from the control memory circle and stored in the microinstruction register αa. As a result, the control signal (5a)
, (5b), (5C) are output. This control signal (5&) + (5b) + (50) selects a register to be added from the register section (2) and sends the value of that register to the arithmetic processing section (3). Next, the control memory address generation section α (a) generates the next microaddress α9 based on the part (5d) of the microinstruction register. As a result, the next microinstruction is read out from the control memory in the same way, and the control signal (5a) is
t (51)) 0 This control signal output as t (5 signal) causes addition to be performed in the arithmetic processing section (3). Next, the control memory address generation section generates the next microaddress, thereby causing the control signal (5
a) # (5b) l (50) is output, and the register that stores the addition result is selected by the control signals (5a), (5b), and (50), and the addition result in the arithmetic processing section is stored in that register. The execution of the add instruction is completed.

In this way, one instruction is executed by a collection of multiple microinstructions, and this collection of microinstructions is called a microprogram.

In addition to addition instructions, the control memo IJ signal 11 stores microprograms corresponding to subtraction instructions, multiplication instructions, etc., and these instructions are also executed in the same way as addition instructions (such control methods (This is called the microprogram control method.)

[Problem to be solved by the invention]

In conventional microprocessors, the control memory is composed of ROM, so when it becomes necessary to change or expand the instructions, the entire chip must be remanufactured, resulting in an increase in cost.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a microprocessor whose instructions can be changed and expanded without remanufacturing the entire chip.

[Means to solve the problem]

The microprocessor according to the present invention is a microprocessor of a microprogram control type, and in particular, a part or all of the control memory is constituted by a replaceable semiconductor storage device, and the control memory address register is stored from outside the microprocessor. a micro-instruction input register; a means for setting a value in the micro-instruction input register from outside the microprocessor; A microprocessor characterized by comprising means for writing a value of an instruction input register.

The means for writing data into the rewritable control memory from outside the microprocessor is to set a microaddress and a microinstruction in the control memory address register and the microinstruction input register from the outside via a port, respectively, and then write the data into the control memory. [Operation] According to the microprocessor according to the present invention, after rewriting a part of the microprogram in the control memory from outside the microprocessor, a microaddress for the rewritten part is generated. The instruction is expanded by executing the instruction that causes the instruction to be expanded.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a microprocessor according to the present invention.

In FIG. 1, (to), α force, (2), α9. Each wire is a shift signal, a series input, a shift signal, a series input,
This is a write signal, and is applied to the control circuit section from the outside as will be described later.

FIG. 2 is a block diagram showing the configuration of the control portion signal in FIG. 1.

In FIG. 2, the control memory address register (6) is constituted by a shift register having a function of shifting one bit by a shift signal section applied from outside the microprocessor. By inputting the serial input α bit by bit while sequentially shifting using the shift signal (2), it is now possible to set any value to the control memory address register α from outside the microprocessor. The microinstruction input register 121D is also a register with a shift function similar to the control memory address register @, and can be set to any value from outside the microprocessor using a shift signal (2) and serial data α9). It has become.

FIG. 3 is a block diagram showing the structure of the control memo IJ signal 11 shown in FIG.

In FIG. 3, RO&5 (c) is an electrically erasable and writable semiconductor memory device (hereinafter referred to as EEPROM).
). For the address input of ROM (a) and 11:lPROM@, part of the micro address signal 5b)
r signal 5o) and signal 5a) are input. Microaddress partial signal 5a) (
d, selector (25a), (25b), (2
In step 5o), it is used to select which of the microinstructions read from the ROM and EEFROM is to be output to the microinstruction register. By applying a write signal section from outside the microprocessor, it is possible to rewrite the contents of the micro address of the control memory address register 0υ to the value of the micro command input register (21).

Next, a method of extending instructions in the microprocessor according to this embodiment will be explained.

In the control memory address generation unit a, the microinstructions output by the EEFROMF 23 are assigned to the selectors (25a), (25b), (250) for a specific instruction hood.
) to generate a microaddress that is selected by the microinstruction register σa and output to the microinstruction register σa.
By rewriting the microinstruction in the ROM (to), any control signal (5a) can be generated for this instruction code.
, (5b), (5o) can be generated, and arbitrary arithmetic processing can be performed.

In other words, it becomes possible to change and expand the types of instructions.

E'F here, PROII! To rewrite the microinstructions in the device, set the microaddress to be rewritten in the control memory address register @, and write the microinstruction input register e.
This is done by setting a microinstruction in 211 and applying a write signal (a) to the EEFROM (c).

Note that in this embodiment, a part of the control memory signal 11) is composed of an IEFROM, but this is replaced by an erasable and writable semiconductor memory device (hereinafter referred to as R1iFROM).
) and static semiconductor memory paternity (SRA).
In this embodiment, the control memory address register (2) and the microinstruction input register 62]) have the same structure.
Although the value is set one bit at a time using the number (to) signal 81 and the serial input signal α9, the same configuration can be achieved even if a plurality of bits are set at once.

〔Effect of the invention〕

As described above, according to the present invention, a part of the control memory in a microprocessor is rewritten from outside the microprocessor, and by providing an instruction code that generates the contents of the rewritten part as a control signal, instructions can be expanded. This can be done without remanufacturing the chip, and has the effect of providing a microprocessor that can be used for customization for special purposes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a microprocessor according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the control circuit section shown in FIG. 1, and FIG. 3 is the block diagram shown in FIG. 2. FIG. 4 is a block diagram showing the configuration of a control memory, FIG. 4 is a block diagram showing the configuration of a conventional microprocessor, and FIG. 5 is a block diagram showing the configuration of a conventional microprocessor.
This figure is a block diagram showing the configuration of the control memory shown in FIG. 4. In the figure, signal) is a control circuit section, (2) is a register section, (3) is an arithmetic processing section, (4) is an instruction register section, and (5) is a register section.
a), (5b) # (50) is the control signal, (5d
) is part of the microinstruction, (6) is the data bus, (7
) address bus, (8) address board, (9) data port, G (I is instruction code, 0℃ is control memory, α is control memory address register, αJ is microinstruction register, a41 is control memory Address generation part, α
9 is a micro address, (2) is a shift signal, aη is a serial input, (2) is a shift signal, 09 is a serial input, 翺 is a write signal, QB is a micro instruction input register, or R
OM, wire is 1 [iEPROMl (24a) p (2
4b) p (24o) is a microinstruction, (25a
)(25b) P (250) is a selector. In each figure, the same symbols indicate the same or equivalent parts〇

Claims (1)

[Claims] An arithmetic processing unit that processes data, a register unit that stores data to be processed, an instruction register that stores coded instructions that specify the type of arithmetic processing, and an arithmetic processing unit and registers. a control circuit section that generates control signals for controlling the microprocessor, the microprocessor comprising: a control circuit section that generates control signals for controlling the microprocessor; A control memory address generation circuit unit that generates an address for sequentially reading data corresponding to a control signal from the control memory to execute an instruction specified by a code in the instruction register, and a control memory for storing this address. A microprocessor equipped with an address register and a microinstruction register for storing data output from a control memory, in particular, a part or all of the control memory is composed of a rewritable semiconductor storage device, and the control memory means for setting a value in an address register from outside the microprocessor; a microinstruction input register; a means for setting a value in the microinstruction input register from outside the microprocessor; and writing in the control memory an address pointed to by the control memory address register. A microprocessor comprising means for writing a value of a microinstruction input register into a possible part.