JPH02201563A - Magnetic disk controller - Google Patents

Abstract

PURPOSE:To prevent destruction of data which is written in a magnetic disk device and should be protected by inhibiting the write to only an arbitrary area of the magnetic disk device where normal data is written. CONSTITUTION:A magnetic disk controller consists of a data transfer circuit 110, a storage circuit 120, and a microprogram control circuit 130. When the indication of data write to an arbitrary cylinder number is received from a central processing unit after a first cylinder number and a last cylinder number which indicate the write inhibit area of the magnetic disk device sent from the central processing unit are stored in the storage circuit 120, it is informed the central processing unit that the indication of write to the write inhibit area is sent from the central processing unit if the arbitrary cylinder number is in the write inhibit area. Thus, destruction of data to be protected is prevented though the indication of write to a data protection area in the magnetic disk device is erroneously sent because of trouble.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic disk control device, and more particularly to processing for protecting data written in a magnetic disk device.

Prior Art Conventionally, the following processing methods have been used to protect data written in this type of magnetic disk device. In other words, in order to protect the data written on the magnetic disk device, it was necessary to turn on the write protection switch attached to the magnetic disk device.
Although it is possible to put any magnetic disk device into a write-protected state, it is not possible to put only an arbitrary cylinder in the magnetic disk device into a write-protected state.

Problems to be Solved by the Invention The only way to protect the data written in the conventional magnetic disk drive described above is to turn on the write protection switch attached to the magnetic disk drive. Normally, it is not possible to write-protect only an arbitrary area in the magnetic disk drive where data is being written, so it is not possible to write to the area in the magnetic disk drive where data is being written. On the other hand, there is a drawback in that when a write instruction is erroneously sent due to a failure of the central processing unit or the like, it is impossible to prevent the data written in the magnetic disk device from being destroyed.

The present invention has been made in view of the above-mentioned conventional situation,
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel magnetic disk control device that makes it possible to eliminate the above-mentioned drawbacks inherent in the conventional technology.

Means for Solving the Problems In order to achieve the above object, a magnetic disk control device according to the present invention includes a data transfer circuit that transfers write/read data between a central processing unit and a magnetic disk device, and a central A storage circuit that stores the first cylinder number and the last cylinder number representing the write-protected area of the magnetic disk device sent from the processing unit, and data writing/reading operations between the central processing unit and the magnetic disk device are data By driving the transfer circuit, the first cylinder number and the last cylinder number representing the write-protected area sent from the central processing unit are stored in the storage circuit, and then the central processing unit issues an instruction to write data to an arbitrary cylinder number. When received, it is compared whether the cylinder number is within the area of the first cylinder number and the last cylinder number that represent the write-protected area stored in the memory circuit, and if it is outside the area, the data is processed normally. and a microprogram control circuit that sends a report to the central processing unit that a write instruction to a write-inhibited area has been sent from the central processing unit if the writing operation is within the write-inhibited area.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, a magnetic disk control device 100 of the present invention
is composed of a data transfer circuit 110, a storage circuit 120, and a microprogram control circuit 130. When the microprogram control circuit 130 receives an instruction to write data to a magnetic disk device (not shown) through a line 202 from a central processing unit (not shown), the microprogram control circuit 130 drives the data transfer circuit 110 through a line 203. Write data taken in from the device through line 200 is transferred to line 201.
When an instruction to read data from the magnetic disk device is received from the central processing unit through line 202, the data transfer circuit 110 is driven through line 203, and data is read from the magnetic disk device through line 201. The microprogram control circuit 130 performs this by sending data to the central processing unit through line 200. When the microprogram control circuit 130 receives the first cylinder number and the last cylinder number representing a write-protected area from the central processing unit through line 202, it sends the data through line 204. Memory circuit 12
Store the cylinder number in 0.

When the microprogram control circuit 130 receives an instruction to write data to an arbitrary cylinder number of the magnetic disk device through the line 202 from the central processing unit, the microprogram control circuit 130 receives the cylinder number representing the write-protected area stored in the storage circuit 120 through the line 204. As a result of the comparison, the microprogram control circuit 130 reads out and compares whether an arbitrary cylinder number is within the write-protected area.
If it is outside the area, the data transfer circuit 1 is transferred through the line 203.
1O, and the write data taken in from the central processing unit through the line 200 is written to the magnetic disk device through the line 201, whereas in the case of inside the area, a write instruction to the write-protected area is sent by the central processing unit. It sends a report through line 202 to the central processing unit.

As described in detail, according to the present invention, after storing the first cylinder number and the last cylinder number representing the write-protected area of the magnetic disk device sent from the central processing unit in the storage circuit, the central processing unit When receiving a data write instruction for a given cylinder number from the device, it is compared to see if the cylinder number is within the write-protected area, and if it is outside the area, the data write operation is executed normally.
If the area is within the write-protected area, the central processing unit sends a report that a write instruction to the write-protected area has been sent from the central processing unit. Even if a write instruction is erroneously sent to the area to be protected due to a failure of the central processing unit or the like, it is possible to prevent the data written in the magnetic disk device from being destroyed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. 100...Magnetic disk control device, 110...Data transfer circuit, 120...Storage circuit, 130...Microprogram III JtM circuit patent applicant NEC Corporation Representative Patent attorney Yutabe Kumagai

Claims (1)

[Claims] In a magnetic disk control device that is connected to a central processing unit, operates according to instructions from the central processing unit, and controls a plurality of magnetic disk devices, write/read data is exchanged between the central processing unit and the magnetic disk devices. A data transfer circuit that performs the transfer, a storage circuit that stores the first cylinder number and the last cylinder number representing the write-protected area of the magnetic disk device sent from the central processing unit, and a storage circuit that receives write/read instructions from the central processing unit. When data is received, data is written/read from the magnetic disk device by driving the data transfer circuit. When an instruction to write data to an arbitrary cylinder number is received from the central processing unit after data is stored in the memory circuit, the area of the first cylinder number and the last cylinder number indicates a write-protected area where the cylinder number is stored in the storage circuit. If it is outside the area, the data write operation is executed normally, but if it is inside the area, the central processing unit sends a report that a write instruction to a write-protected area has been sent from the central processing unit. A magnetic disk control device comprising: a microprogram control circuit that sends data to the device.