JP2512948B2 - Data processing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing device having an input / output buffer with an external storage device and capable of asynchronously writing to the external storage device. ,
When a storage medium such as a floppy disk (hereinafter, simply referred to as "medium") is replaceable, the data processing device is capable of performing the writing to the buffer and the medium at the same time so that the medium can be replaced at any time. Regarding

Prior Art An operating system that has many internal buffers, such as the UNIX operating system developed by Bell Laboratories of AT & T in the United States, and that can write data in these internal buffers asynchronously to an external storage device. -In the system, not only general users but also system administrators cannot know whether unwritten data remains in the main memory. Therefore, if the external storage device is a medium exchangeable device such as a floppy disk, the user thinks that the data writing is completed,
There was a risk of replacing the floppy disk.

Also, if you replace the floppy disk in the above condition, the data on the newly inserted floppy disk and the data you intended to write previously may be mixed, and the data on the new floppy disk may be destroyed. there were.

The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-mentioned problems in the conventional system and to provide a medium exchangeable such as a floppy disk in the external storage device. The purpose is to provide a data processing device which enables a user to perform the medium exchange without being aware of whether or not unwritten data remains in the main memory.

Configuration The above object of the present invention is to provide a means for checking whether or not the external storage device can exchange media in a data processing device having an external storage device and an input / output buffer with the external storage device, In the processing of a data write request from the user to the external storage device, if the external storage device is a medium exchangeable device, the data is copied to the buffer and immediately written to the external storage device. It is achieved by a data processing device characterized by the above.

In an operating system such as the above-mentioned UNIX operating system capable of performing asynchronous write processing, many buffers on the main memory are used for control. There are two control flows: a process of requesting writing of buffer data to the external storage device and a process of actually writing buffer data to the external storage device. The present invention can be said to enhance the cooperation between the two.

Hereinafter, the configuration of the present invention will be described in more detail based on examples.

FIG. 1 is a block diagram showing a system configuration according to an embodiment of the present invention. In the figure, 1 executes an instruction stored in a main storage device 3 described later, and the external storage control device described below. Operation control unit (CP with the function to execute data transfer etc.
U) and 2 are data transfer between an external storage device such as a hard disk (HDD) 4 and a floppy disk (FDD) 5 and the following main storage device (MEM) 3 in accordance with the instruction from the arithmetic and control unit 1 described above. An external storage control device (IOC) 3 is a main storage device in which the above-mentioned operating system programs and application programs are stored.

FIG. 2 is a diagram exemplifying the usage status (contents) of the main storage device 3, and the above-mentioned buffer area also exists inside this. FIG. 3 shows an example of the buffer management data in FIG.

FIG. 4 is a flow chart for explaining the operation of this embodiment configured as described above. The operation will be described below according to this.

When there is a write request from the application program, the arithmetic and control unit 1 first searches for an empty buffer in the main memory 3 (step 11). This search for an empty buffer is to search for a buffer management data BUSY in the main memory 3 shown in FIG. 3 that is not "in use". When a free buffer is obtained, the BUSY information corresponding to this buffer is set to "in use" (step 13).

Here, if there is no empty buffer, the LRU information of the above-mentioned buffer management data is checked to select the buffer that has not been used most recently (step 12). Next, of the buffer management data of the selected buffer
DIRTY is checked to see if its contents have already been written to the external storage device (step 14). If it has not been written, an instruction is given to the external storage control device 2 to write the unwritten data held in the buffer to the external storage device (step 15). After writing, the DIRTY information of the buffer management data is set to the written state. Next, the write data specified by the application program is transferred to the buffer, and the above-mentioned buffer management data is transferred.
DEV and BLK are updated (step 16). If it has been written, the process of step 16 is directly performed.

Next, in step 17, it is checked whether the medium of the external storage device of the writing destination is exchangeable. This judgment is made by checking the DEV of the buffer management data.
If the medium of the external storage device at the write destination is exchangeable, the unwritten data held in the buffer
Writing to the external storage device (step 18), and after writing, the DIRTY information of the buffer management data is set to the written state. If the medium of the external storage device of the writing destination is not a replaceable medium, the process ends.

According to the above embodiment, the external storage device in which the medium can be exchanged can be exchanged at any time, so that there is an effect that operability and reliability are improved.

In the above-mentioned embodiment, the floppy disk has been described as an example of the external storage device capable of exchanging the medium.
The present invention should not be limited to this, and can be applied to an external storage device using a cartridge disk, a tape or the like.

Effect As described above, according to the present invention, in a data processing device having an external storage device and an input / output buffer with the external storage device, it is checked whether or not the external storage device is a storage medium replaceable. Means for providing a data write request from the user to the external storage device,
In the case where the external storage device is a storage medium exchangeable medium, since the data is copied to the buffer and immediately written to the external storage device, the external storage device can exchange the medium like a floppy disk. In this case, a remarkable practical effect that a user can realize a data processing device capable of performing the medium exchange without being aware of whether or not unwritten data remains in the main memory is exerted. It is a thing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of contents of a main storage device, FIG. 3 is a diagram showing an example of buffer management data, and FIG. 3 is a flowchart for explaining the operation of the arithmetic and control unit. 1: arithmetic control device, 2: external storage control device, 3: main storage device,
4: Hard disk, 5: Floppy disk.

Claims (1)

(57) [Claims] 1. A data processing device having an external storage device and an input / output buffer for the external storage device, comprising means for checking whether or not the external storage device is a storage medium replaceable device, In the process of requesting data write to the external storage device, if the external storage device has a replaceable storage medium, the data is copied to the buffer and then immediately written to the external storage device. Characteristic data processing device.