JPH03125243A - External memory driving system - Google Patents

Abstract

PURPOSE:To facilitate the write/read of the order of data of an external memory by increasing/decreasing the contents of a counting device every time the data are written or read by a prescribed unit after setting a head address to the counting device. CONSTITUTION:When data are written into an external memory 16, the count value corresponding to the head address of a write executing area of the memory 16 to a counting device 15. Then the count contents of the device 15 are increased by 1 for each prescribed data unit after a data writing action is started. When data are read out of the memory 16, the count value corresponding to the head address of a read executing area of the memory 16 is set to the device 15. Then the count contents of the device 15 are decreased by 1 for each prescribed data unit. Thus the write/read of the order of data can be faciliated.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an external memory drive system, and in particular, a system in which a simple control device and a counting device are attached to a relatively small-scale central processing unit. The present invention relates to an external memory driving system that can easily perform sequential writing and sequential reading of data.

[Prior Art] FIG. 2 is a schematic configuration diagram showing a conventional external memory drive system. In FIG. 2, the central processing unit (21) is connected to an external memory (23) via an input/output channel (22).
is connected. In this conventional example, the external memory (23) is used, for example, to obtain operating information. Now, assuming that a relatively small-scale microprocessor is used as the central processing unit (21), its memory space is limited, so it is difficult to connect a large-capacity external memory (23). However, it is also possible to use an appropriate memory unit by installing an appropriate MMU (memory management unit) and performing bank switching, etc. In this case, it is possible to operate at high speed and with good efficiency. However, the problem is that the software required to do so becomes complicated. Furthermore, it is also possible to use an external mechanical unit such as a floppy disk, and although in this case a large capacity can be stored, the necessary equipment becomes large-scale as a whole, and the The drive speed becomes slow.

[Problems to be Solved by the Invention] As mentioned above, in the conventional external memory drive system, when the central processing unit has limited memory space, it is not possible to connect a large-capacity external memory, and it is difficult to connect an appropriate external memory. M
When an MU is provided and an appropriate memory unit is used, the software for backing up its operations becomes complicated, and when a mechanical unit such as a floppy disk is used as external memory, the device as a whole becomes bulky. At the same time, there is a problem that the driving speed becomes slow.

This invention was made in order to solve the above problems, and it is possible to easily write and read data in order by simply adding a simple control device and a counting device. The purpose of this invention is to provide an external memory drive system that provides a

[Means to solve the problem]

The external memory drive method according to the present invention is a drive method for writing and reading data between a central processing unit and an external memory via an I/O interface, the method comprising: A control device and a counting device are interposed between the external memory and the external memory, and a start address for writing or reading data to the external memory is set in the counting device under the control of the control device, and the data is read or written to the external memory. The present invention is characterized in that the content of the counting device is increased or decreased each time writing or reading is performed in a predetermined unit.

[Operation] According to the present invention, sequential writing and sequential reading of data to and from the external memory can be easily performed by appropriate operation of the attached control device and counting device.

Embodiment FIG. 1 is a schematic diagram showing an external memory drive system according to an embodiment of the present invention. In FIG. 1, address data from a central processing unit (11) is subjected to necessary decoding operations by a subsequent address decoder (12) and then applied to an I/O interface (13)6. The required data from the central processing unit (11) is applied to the external memory (16) via the I/O interface (13). Note that this external memory (16) has a decoder (16^) and multiple sections of S.
It consists of RAM (16B). And I
A control bag ff (14) and a counting device (15), which will be described later, are interposed between the /O interface (13) and the external memory (16).

The control device (14) performs the following operations based on signals from the I/O interface (13). That is, external memory (
16), the count value corresponding to the start address of the write execution area of the external memory (16) is counted! (15), and after the execution of the data write operation has started, a count device is set for each predetermined data unit. (15) count content is 1
increase only. On the other hand, external memory (16
), when reading data from the external memory (1
6) The count value corresponding to the start address of the reading execution area is set in the counting device W (15), and the count content of the counting device (15) is set to 1 for each predetermined data unit.
will be reduced only.

As described above, embodiments of the present invention provide a method for sequentially writing and ordering data to an external memory used with a relatively small-scale central processing unit by simply adding a control device and a counting device to the external memory. It can be particularly advantageously applied to cases where reading is easy and the order of data input and output is fixed, and a specific field of application is sequence robots. Can list fields.

[Effects of the Invention] As explained above, the external memory drive method according to the present invention is a drive method that writes and reads data between a central processing unit and an external memory via an I/O interface. A control device and a counting device are interposed between the I/O interface and the external memory, and a start address for writing or reading data to the external memory is controlled by the control device. The counter is set at the bottom of the counting device, and the contents of the counting device are increased or decreased each time writing or reading of the data is executed in a predetermined unit.

Therefore, according to the present invention, by simply adding a simple control device and a counting device to a relatively small-scale central processing unit, sequential writing and sequential reading of data can be easily performed. is played.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an external memory driving system according to a first embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing a conventional external memory driving system. (11) is the central processing unit, (12) is the address decoder, (13) is the ■/○ interface, (14) is the control device, (15) is the counting device, 1st Figure 6A: Decoder 168: SRAM

Claims (1)

[Claims] (1) An external memory drive method for writing and reading data between a central processing unit and an external memory via an I/O interface, the method comprising: A control device and a counting device are involved, and a start address for writing or reading data to the external memory is set in the counting device under the control of the control device, and writing or reading of the data is performed at a predetermined time. An external memory drive method, characterized in that the content of the counting device is increased or decreased every time execution is performed in units of .