JPH01216428A - System for executing subroutine of memory bank - Google Patents

Abstract

PURPOSE:To make address adjustment at plural parts unnecessary and to reduce the developing time of a program by storing the address of a subroutine in a memory bank to be executed at a prescribed register first in a main routine on one side. CONSTITUTION:In the specific same address areas 9 of the memory banks 1 and 2, a bank switching control program, that is a bank switching manager is stored, and in a processing program area 10 behind the area 9, a different processing program is stored. In the memory bank 1, when the bank switching manager is called in the main routine after transferring an address Y to a register BX, the bank is switched from 1 to 2 by the bank switching manager, and the subroutine starting from the address Y set in the register BX is called by the bank switching manager of the memory bank 2, and the subroutine is executed. In such a way, it is possible to make complicated address adjust ment between the memory banks unnecessary, and to improve the working efficiency of program development.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention provides a system in which different processing programs are stored in first and second memory banks. This paper relates to a memory bank subroutine execution method that calls and executes subroutines within the bank.

(b) Conventional technology A memory bank switching method is generally used as a method to expand the memory area of a central processing unit (hereinafter referred to as CPU), and different processing programs are stored in these memory banks. This has also been done conventionally. Usually, a control program for memory bank switching is prepared in a common area on the main memory outside the memory banks, and the switching of these memory banks is executed by this control program.

However, in systems where the program area is restricted and such a common area cannot be allocated on the main memory, bank switching control must be executed within the memory bank. 1986-12
As disclosed in FIG. 3 of Publication No. 0543, in the main routine of one memory bank, a bank switching instruction is executed at the address X at which the bank is to be switched, and the next address X+1 or X+2
A method was adopted in which the execution was transferred to

(8) Problems to be Solved by the Invention When attempting to call and execute a subroutine of the other memory bank from the main routine of one memory bank using the switching method disclosed in Figure 3 of the above publication, the program development When doing so, the bank switching address of the main routine and the start address of the subroutine must be matched at multiple locations where the main routine attempts to call the subroutine, which requires a lot of time in program development. Moreover, if there are many subroutines to be called, it may become impossible to develop the desired program due to the restriction that the addresses must match.

However, if you try to simply store all the subroutines used in a memory bank in its own memory bank, the required memory capacity will increase, and only the desired program can be stored in the restricted program memory area. I can't bear it anymore.

(D) Means for Solving the Problems The present invention comprises first and second memory banks for storing processing programs, stores a bank switching control program in the same specific address area of both memory banks, and The main routine in the processing program in the memory bank stores the address of the subroutine in the other memory bank to be executed in a predetermined register, and after storing, calls the bank switching control program in the same memory bank. At the same time, the bank switching control program on the main routine side stores a bank switching command and a return command to the main routine, and the bank switching control program on the subroutine side stores the above command after executing the bank switching command. An instruction to call a subroutine starting from the first address stored in a predetermined register,
A bank switching instruction for switching banks after execution of the subroutine by the instruction is stored, and the return instruction is executed after the execution of the bank switching instruction, thereby realizing calling and executing the other subroutine from one main routine. This method solves the above problem.

(*> Effect In the present invention, in one main routine, the address of the subroutine in the other memory bank to be executed is first stored in a predetermined register, and after being stored, the address of the subroutine to be executed in the other memory bank is specified by the bank switching control program in the own memory bank. Banks are switched within the address area, and the bank switching control program of the switched memory bank performs bank switching within the above-mentioned specific address area by the subroutine within the same bank, and common link switching control of the switched memory bank is performed. The program returns to the main routine.

(v) Embodiment FIG. 2 shows the steps for realizing the embodiment of the present invention. (4)
(5) is a ROM serving as a memory bank 1 that stores a first processing program, and (5) a ROM serving as a memory bank 2 that stores a second processing program.

(6) is a RAM as a main memory for storing various data and user programs loaded from external devices, and (7) is a RAM that is used as a main memory for storing various data and user programs loaded from external devices. The bank register (8) is a decoder that selects one of the given memory banks according to the contents of the bank register (7), and the hardware configuration is a typical one. It is the composition. When configuring two or more memory banks using the same ROM chip, the configuration disclosed in Japanese Patent Application No. 61-252195 may be used, and these configurations are not related to the gist of the present application. .

Figure 1 shows memory bank 1 (4) and memory bank 2.
(5) is a diagram showing the program contents, in which a bank switching control program (hereinafter referred to as bank switching manager) is stored in the same specific address area (9) of both memory banks, and the processing from the area (9) onwards. Program area (1
0) respectively store different processing programs.

An example of calling and executing a subroutine of memory bank 2 (5) from the main routine of memory bank 1 (4) will be described below.

First, in the memory bank 2, there are a plurality of subroutines 5U.
BI, 5U-B2. ...old... is memory bank 1
For example, in this main routine, the address X to call subroutine 5UB1 is stored independently of the subroutine call address of the main routine
, set address Y of subroutine 5UB1 to register BX.
The MO■ instruction to transfer to the next address
A CALL command to call the bank switching manager starting from address O is stored in .

Furthermore, the bank switching manager of memory bank 1 has a bank switching command to switch the bank from 1 to 2 at address 0;
JMP# at address 1, NOP command at addresses 2 to 4,
The RET command has been stored at address 5. On the other hand, the bank switching manager of memory bank 2 has addresses 0,
N to 1.5.

P instruction, address 3 is a CALL instruction that calls a subroutine starting from the address set in register BX, address 4 is a bank switching instruction that switches the bank from 2 to 1, address 5 is JMPI! + is memorized.

Therefore, in the main routine in memory bank 1, when the bank switching manager is called after transferring address Y to register BX, the bank switching manager switches the bank from 1 to 2, and after switching, memory bank 2
The bank switching manager allows the subroutine starting from the address set in register BX, that is, address Y, to be called completely, and this subroutine can be completely executed. After execution, the RET command returns to the bank switching manager, the bank is switched from 2 to 1 by the manager ~-, and after the switching, 'RE' in the bank switching manager of memory bank l is
The T instruction is executed and the process returns to address X+2 of the main routine. In other words, the main routine of one memory bank can call and execute the subroutine of the other memory bank. When subroutine 5UB2 is called, address W of 5UB2 may be transferred to register BX using the MOV instruction.

By the way, in order to be able to mutually call the subroutines of memory bank 1 from the main routine of memory bank 2, double the area (9) and use the same bank switching manager as that of memory bank 1 in memory bank 2. Then, a bank switching manager similar to that of memory bank 2 is added remotely to memory bank 1, and the main routine of memory bank 2 uses the MOV command and the added bank switching manager in the same way as the main routine of memory bank 1. All you have to do is execute a CALL instruction that calls .

(G) Effects of the Invention According to the present invention, there is no need for troublesome address matching between memory banks, and subroutines can be placed at any address within the memory bank, which improves work efficiency in program development. will improve.

Furthermore, since bank switching can always be performed within a specific address area, the program area for switching can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIG. 2 is a block diagram showing the hardware configuration of the embodiment. (1)...CPU, (2)...Address bus,
(3)...Data bus, (4)...Memory bank 1
, (5)...Memory bank 2, (7)...Bank register.

Claims (1)

[Claims] (1) comprising first and second memory banks for storing processing programs, storing a bank switching control program in the same specific address area of both memory banks, and storing a main routine in the processing program in one memory bank; Then, store the address of the subroutine in the other memory bank to be executed in a predetermined register, and after storing,
The bank switching control program in the same memory bank is called, and the bank switching control program on the main routine side stores a bank switching instruction and a return instruction to the main routine, and the bank switching control program on the main routine side stores a bank switching instruction and a return instruction to the main routine. The bank switching control program stores an instruction to call a subroutine starting from a start address stored in the predetermined register after executing the bank switching instruction, and a bank switching instruction to switch banks after executing the subroutine according to the instruction, A subroutine execution method for a memory bank, characterized in that one main routine calls and executes another subroutine by executing the return instruction after executing the bank switching instruction.