JPH07122850B2 - Integrated circuit device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to integrated circuit devices, and more particularly to integrated circuit devices for transferring microprograms to random access memory.

[Conventional technology]

In a microprocessor controlled by a microprogram, if the microprogram itself needs to be rewritten during operation, the microprogram is stored in RAM.
It must be stored in (random access memory). Conventionally, such a microprocessor performs a startup operation of copying a microprogram stored in a ROM (Read Only Memory) into the RAM when the power is turned on. That is, a ROM in which a necessary microprogram is written is prepared, and immediately after the power is turned on, the microprocessor is made to access the ROM to read the microprogram and write it in the RAM.

[Problems to be solved by the invention]

However, the conventional method has a problem that a large number of extra input / output terminals are required to copy a microprogram. That is, between the ROM storing the microprogram and the microprocessor,
A certain number of data lines and address lines are required. As the bit width of microinstructions increases, the number of data lines must be increased, and as the capacity of microprograms increases, so does the address space.
ROM has to be prepared, and eventually the number of address lines must be increased.

Therefore, an object of the present invention is to provide an integrated circuit device capable of transferring a microprogram to a RAM with as few input / output terminals as possible.

[Means for solving problems]

According to the present invention, (a) an address for inputting a preset signal and a clock signal from a microprocessor, setting an address count value to an initial value when the preset signal is input, and updating the address count value based on the clock signal thereafter. A counter and (b) a microprogram formed on the same semiconductor chip as this address counter for controlling the microprocessor are stored, and each time the address is designated by the address count value given from the address counter. By using an integrated circuit device equipped with a read-only memory that outputs corresponding data to the microprocessor bit by bit, this RO
The microprogram stored in M is transferred to RAM, and the number of extra input / output terminals is reduced.

〔Example〕

 The present invention will be described below based on the illustrated embodiments.

FIG. 1 is a block diagram showing a state in which an integrated circuit device according to an embodiment of the present invention is connected to a microprocessor. The integrated circuit device 100 according to this embodiment includes an address counter 10 and a PROM 20. Address counter
10, the preset signal a from the microprocessor 200
And a clock signal b. In addition, 1-bit data c is output from the PROM 20 to the microprocessor 200. On the other hand, the address count value d is given from the address counter 10 to the PROM 20. Microprocessor 200
The RAM 300 and the boot ROM 400 have a plurality of lines e and f (address lines, data lines, etc.) as in the conventional technique.
Connected through. In the boot ROM 400, a micro program showing a startup procedure when the power of the microprocessor 200 is turned on is written. In addition, a microprogram for controlling the microprocessor 200 is written in the PROM 20. After power-up, this microprogram is transferred to RAM300 and the microprocessor 200
Operates according to the microprogram transferred to the RAM 300.

Next, the operation of this integrated circuit device 100 will be described. First, when the power is turned on, the microprocessor 200
The microprogram written to 0 is read out via the line f, and the following procedure is executed according to this microprogram.

Introduction Microprocessor 200, address counter 1
A preset signal a is given to 0. As a result, the address counter 10 sets the address count value to a predetermined initial value. Subsequently, the microprocessor 200 starts supplying the clock signal b to the address counter 10. The address counter 10 updates (increments or decrements) the address count value from the initial value based on the clock signal b. The address count value d at each update is given to the PROM 20, and each address count value can access the PROM 20 in 1-bit units.

Therefore, the PROM 20 outputs the addressed 1-bit data c to the microprocessor 200. In this way, the microprogram in the PROM 20 is loaded into the microprocessor 200 bit by bit in synchronization with the cycle of the clock signal b.

The microprocessor 200 temporarily stores the fetched 1-bit data for n bits, and transfers the n bits collectively to the RAM 300 via the line e. Where n is RA
This is the data bit width of M300. The storage address in the RAM 300 is updated every n-bit transfer.

In this way, the microprogram in the PROM 20 is taken into the microprocessor 200 bit by bit, and is collected for n bits and transferred to the RAM 300.

When the transfer of the microprogram is completed, the microprocessor 200 switches the operation from the execution of the microprogram in the boot ROM 400 to the execution of the microprogram in the RAM 300. After that, the microprocessor 200
It will be controlled by the microprogram transferred into 300.

As described above, when the microprogram is transferred using the integrated circuit device according to the present embodiment, the input / output terminals for the three signal lines of the preset signal a, the clock signal b and the 1-bit data c are extra. It only needs to be installed in. Even if the bit width of microinstruction increases or the capacity of microprogram increases, it is always 1 from PROM20.
Since the data is output in bit units, the number of extra input / output terminals does not increase.

Although the PROM 20 is used to store the microprogram in the above-described embodiment, a mask ROM may be used as a matter of course.

〔The invention's effect〕

As described above, according to the present invention, the read-only memory stores the microprogram for controlling the microprocessor. Then, the microprocessor supplies a preset signal and a clock signal to read the micro program, and the microprocessor outputs the data output bit by bit from the read only memory again. Therefore, the microprocessor takes in data bit by bit with the clock signal output by itself, so that no special synchronization is required. Further, since the microprocessor directly takes in the serial data and collects the serial data into unit data of n bits each forming a microinstruction, not only a counter circuit is not required, but even if the bit width of the microinstruction increases or decreases. Can correspond to. Of course, even if the bit width of the microinstruction increases, no extra input / output terminals are needed, and it is sufficient to prepare a minimum number of input / output terminals, so that the integrated circuit device can be manufactured at low cost. is there.

[Brief description of drawings]

FIG. 1 is a block diagram showing a state in which an integrated circuit device according to an embodiment of the present invention is connected to a microprocessor. 10 …… Address counter, 20 …… PROM, 100 …… Integrated circuit device, 200 …… Microprocessor, 300 …… RAM, 400 …… Boot ROM, a …… Preset signal, b …… Clock signal, c …… 1-bit data, d ... Address count value, e, f ... Multiple lines.

Claims (2)

[Claims] 1. A microprocessor inputs a preset signal and a clock signal, sets an address count value to an initial value when the preset signal is input, and thereafter updates the address count value based on the clock signal. An address counter and a microprogram for controlling the microprocessor, which is formed on the same semiconductor chip as the address counter, are stored, and each time the address is designated by the address count value given from the address counter. An integrated circuit device comprising: a read-only memory that outputs corresponding data bit by bit to the microprocessor. 2. The integrated circuit device according to claim 1, wherein the preset signal and the clock signal are input from the microprocessor, and 1-bit data is output to the microprocessor.