JPS60173631A - Control program switching system - Google Patents

Abstract

PURPOSE:To attain a connection of an external device different from conventional system by disconnecting an external memory storing a control program having the same address constitution as a ROM in which a control program is stored to change over both the control programs. CONSTITUTION:A ROM12 adopts the same address constitution as that of a ROM3' to which a conventional control program is stored and a control program required for the control of an external device 8' is stored in addition to the control program stored in the ROM3'. When the external device 8' and a main body 1' are connected by a connector 7', a CS' signal fed to the ROM3' from an output side of a NAND gate 11 is brought forcibly into an H level by the earthing signal from the external device 8' to stop the operation of the ROM3'. The control program is read and executed from the ROM12 by a processor 2', which controls processings including a processing relating to data transfer with the external device 8'.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention is based on a system in which a control program is stored in a read-only memory (ROM), and the bus can be expanded. The present invention relates to a data processing device that can be connected to a computer.

(2) Prior Art and Problems Figure 1 is a block diagram of a conventional data processing device.
1 is the main body, 2 is the processor, 3 is the read-only memory,
4 is an input/output device, 5 is a bus, 6 is a driver/receiver,
7 represents a connector, and 8 represents an external device.

In FIG. 1, a control program for this data processing device is stored in a read-only memory 3, and a processor 2t reads the control program sound from the read-only memory 3 and executes it. The input/output device 4 is connected to the bus 5 and is controlled by the processor 2 executing a control program stored in the read-only memory 3. The external device 8 is connected to the bus 5 via the driver/receiver 6 and also transfers the control program read from the read-only memory 3 to the processor 2.
The transfer of data is controlled by the execution of

In such data processing devices, as mentioned above, data transfer with external devices is controlled by a control program stored in read-only memory in advance, so it is assumed that the connection will be made in advance. Only external devices that have a built-in control program can be used.

Therefore, when connecting a newly developed external device with different performance or control conditions, the read-only memory inside the main body must be replaced again, making it difficult to handle.

(3) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention provides a system in which control programs and the like are not stored in a read-only memory in advance, and even external devices of a completely different type from conventional devices can be easily connected. is intended to provide.

(4) Structure and object of the invention According to the present invention, as described in the claims, there is provided a read-only memory in which a control program is stored and a processor, which are connected by a path. In a data processing device, means capable of stopping the operation of the read-only memory and means capable of connecting an external memory to the path are provided, and the device stops the operation of the read-only memory and has the same address as the read-only memory. This is achieved by a control program switching method characterized in that an external memory having a configuration and storing a control program is connected to the path so that the processor reads the control program from the external memory and executes it.

(5) Embodiment of the invention FIG. 2 is a block diagram of an embodiment of the invention, 1' to 1.
3', 6' to 8' are the same as in FIG. 1, 9 is a data bus, 10 is an address bus and control line, 11 is a NAND gate, 12 is a single-drive only memory, and 13 is an input/output controller. .

In FIG. 2, a control program is stored in a read-only memory 3', and normally, when an external device 8' is not connected, a processor 2' reads and executes the control program, thereby controlling the main body 1. ′ works. However, the control program does not include a control program for controlling the external device 8'. On the other hand, the read-only memory 12 has the same address structure as the read-only memory 173', and in addition to the same control program as the one stored in the read-only memory 3', it also contains control programs necessary for controlling the external device 8'. Stored. Then, when the external device 8' and the main body 1' are connected by the connector 7', the surface signal supplied from the output side of the NAND game h'11 to the single-drive only memory 3' is forced by the earth from the external device 8'. The read-only memory 3' is temporarily set to the 1H level, and the read-only memory 3' stops operating. and processor 2
By reading a control program from the read-only memory 12 and executing it, ' can perform control including processing related to data transfer with the external device 8'. Since the read-only memory 3' and the read-only memory 12 have exactly the same address structure, the processor 2' can operate without being aware that the read-only memory has been switched.

This example describes a system in which the read-only memory is automatically switched by electrically connecting the main unit and external equipment with a connector, but all switches on the main unit are manually switched. You can also do it.

Furthermore, when the control program is changed to improve performance or the like, instead of using an external device, it is possible to easily upgrade the level by installing a read-only memory that stores the new control program.

(6) Effects of the Invention As explained in detail above, according to the method of the present invention, a data processing device can be controlled by a program stored in a memory connected to the outside of the main body. For example, when a new external device is developed, even if conventional data processing equipment does not have the ability to control it,
It is possible to store an O8i containing a program that can control the external device in the memory of the external device, and automatically switch the control system when the external device is connected to the main body. be. Therefore, when developing the main body, there is an advantage that the troublesomeness of considering the conditions of external equipment that will be developed later can be avoided, which is very effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional data processing device, and FIG. 2 is a block diagram of an embodiment of the present invention. ■, 1'...Main body, 2.2'...Processor, 3.
3'...Read-only memory, 4...I/O device,
5...Has, 6.6'...Driver/receiver, 7
．． 7'...Connector, 8.8'...External device, 9.
...Data bus, 10...Address bus and control &'J
, 11... NAND gate, 12... Read only memory, 13... Input/output controller Patent attorney Hiroshi Matsuoka

Claims (1)

[Claims] In a data processing device having a read-only memory storing a control program and a processor and connected by a bus, means capable of stopping the operation of the read-only memory, and an external memory connected to the bus. and means for stopping the operation of the read-only memory and connecting an external memory having the same address configuration as the read-only memory and storing a control program to the bus, so that the processor can read from the external memory. A control program switching method characterized by reading and executing a control program.