JPS6118043A - Rom control system - Google Patents

Abstract

PURPOSE:To enable another extended ROM to refer to the result of execution by calling successively the procedure entrances of an extended ROM by a basic ROM and storing the result of execution of the procesdure called by the extended ROM to a common memory. CONSTITUTION:A basic ROM calls the initialization procedures for extended ROM-A and -B, and the called ROM starts an action to the FFA and FFB respectively and sends immediately the control to the basic ROM. When the processing is through with both ROM-A and -B, it is decided that both floppy disks FPA and FPB are working. Then the basic ROM calls the next initialization procedure for both ROM-A and -B. The called ROM sets the presence or absence of an FP as well as the number of FPs to a common memory after the action started by the preceding initialization procedure is over and then sends the control back to the basic ROM. Then the basic ROM calls the initial program reading procedure, and the called extended ROM reads the initial programs out of the FPA and PFB respectively, and leaves the control to these initial programs.

Description

DETAILED DESCRIPTION OF THE INVENTION Ento (1) The present invention relates to a control method for a ROM (read only memory), and particularly to a control method for an expansion ROM in a microcomputer.

BACKGROUND ART Conventionally, microcomputers have been equipped with an external storage device such as a floppy disk in order to expand their performance and functions, and an expansion ROM corresponding to this external storage device has been prepared and the procedures for this expansion ROM have been executed by the operating system. After startup, the operating system calls and executes programs from the external storage device.

This means that the operating system must be read from the external storage device and the program to be started must be stored in the basic ROM in advance. Therefore, when connecting an external storage device with a different control method, the basic ROM must be replaced. There is a drawback that it must be done.

Also, the expansion ROMs are called sequentially by the operating system, and each expansion ROM is called by the operating system.
Since procedures are executed independently of M, there is a drawback that it is difficult to combine the functions of expansion ROMs.

OBJECTS OF THE INVENTION An object of the present invention is to provide a ROM control method that solves the above-mentioned drawbacks by providing an expansion ROM with a plurality of procedure entrances, and also allows expansion of the expansion ROM and control of an advanced 4T expansion ROM. It is to be.

Structure of the Invention The ROM control method according to the present invention includes a basic ROM (read-only memory), an expansion ROM having a plurality of procedure entry points that are called and controlled by the basic ROM, and -C corresponding to the expansion ROM. The basic ROM sequentially calls the procedures in the expansion ROM, and the expansion ROM executes the called procedures. It is characterized in that the results are stored in a common memory, and the stored execution results can be referenced by other expansion ROMs.

in one boat The present invention will be explained in detail below using the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention, which includes a basic ROM-\, external storage radicals such as floppy disk A-D, and floppy disk C.
, D are reserved. There are expansion ROMs A and B for controlling floppy disks A and B, respectively.
represent the initialization procedures 1 and 2, the initial program loading procedure, and the input/output procedure, respectively. These basic ROM and expansion R
There is a common memory for OM, and this common memory glue! The new reference is made in common from the basic ROM and expansion ROM.

21 and 3 are flows showing the operations of the basic ROM, and FIGS. 4(A) to (D) are flows showing the operations of the expansion ROM. Note that O8 in the flow stands for the operating system. The operation of the system shown in FIG. 1 will be explained with reference to FIGS. 2 to 4.

The basic ROM is an extended ROM-A with initialization procedure 1.

The called expansion ROM starts operations on the floppy disk devices A and B, respectively, and immediately returns control to the basic ROM. When the above processing of expansion ROM-A and B is completed, the floppy disk device Ft
This means that A and B are both operating. Incidentally, it is assumed that no expansion ROM corresponding to floppy disk devices C and D exists, so no calls are made.

Next, the basic ROM performs the initialization procedure 2 in the extended ROM-A and B.
This called expansion ROM waits for the completion of the operation started in the previous initialization procedure 1, and when the operation is finished, it sets the existence and number of floppy disk devices in the common memory, and returns it to the basic R9M. ! It will return ll III.

Then, the basic ROM calls the initial program reading procedure, and the called expansion ROM reads the initial program from the floppy disk drives NA and B, respectively, and transfers control to this initial program. However, if the initial program cannot be read, control is returned to the basic ROM. When the basic ROM calls the initial program reading procedure for the expansion ROMs A and B and all control is returned, the process proceeds to the next step.

I/O procedures are called from the operating system via the basic ROM. When this operating system calls this input/output procedure, it has input/output information that indicates which floppy disk device to select, and uses the basic ROM to determine which one of this input/output information - base expansion ROM to call. . The input/output information is generated based on the presence or absence of floppy disk devices stored in the common memory and the number of floppy disk devices.

Summary of the above operation - The basic ROM sequentially calls all of the multiple procedure entrances of the expansion ROM, and
stores the results of the procedure in common memory. Then, when the basic ROM makes a cycle of procedure calls in all expansion ROMs and calls the next procedure, the called expansion ROM refers to the execution results of procedures in other expansion ROMs. Also, basic R
Of course, the common memory can also be referenced by the OM and the operating system.

In this way, an expansion ROM can branch to different procedures depending on the presence of other expansion ROMs and processing results, and it is also possible to establish procedures common to multiple expansion ROMs before the operating system is started. becomes.

Effects of the Invention According to the present invention, when connecting a new external device, an interface with the operating system can be established without changing the basic ROM in the expansion ROM. This has the effect of increasing the expandability of the microcomputer system, such as by allowing the operating system to be started without changing the basic ROM when connecting the external storage device.

[Brief explanation of the drawing]

FIG. 1 is a schematic system block diagram explaining the present invention in detail, and FIGS. 2 and 3 are further diagrams showing the operation of the basic ROM.
1. Figure 4 (A) and (D) are flowcharts showing the operation of the expansion ROM.

Claims (1)

[Claims] A basic ROM (read only memory), an expansion ROM having a plurality of procedure entrances that are called and controlled by this basic ROM, an external device provided corresponding to this expansion ROM, and the basic ROM and the expansion ROM. and a common memory that can be commonly updated and referenced, and the basic RO
sequentially calls the procedure entrances of the expansion ROM by M;
ROM control for a microcomputer, characterized in that the expansion ROM stores the execution result of the called procedure in the common memory, and allows other expansion ROMs to refer to the stored execution result. method.