JPH02202654A - Magnetic disk controller - Google Patents

Abstract

PURPOSE:To prevent the breakdown of data by executing comparison to check whether it is a write instruction within the area of write inhibition or not when the write instruction to data corresponding to a block number is received. CONSTITUTION:When a microprogram control circuit 130 receives a head and a final block numbers on a specified track to express the write inhibition area from a CPU through a line 202, it stores them in a storage circuit 120 through the line 204. When the circuit 130 receives the write instruction of data to the optional block of the optional track of a magnetic disk device from the CPU, it reads out the block number of the write inhibition area stored in the circuit 120, and executes the comparison to check whether this block number lies within the write inhibition area or not. In the case where the result of the comparison is outside the write inhibition area, the circuit 130 drives a data transfer circuit 110 through the line 203, and writes write-in data fetched from the CPU to the magnetic disk device through the line 201, and on the contrary, in the case of within the inhibition area, it sends a report purporting that the write instruction for the write inhibition area was sent from the CPU to the CPU through the line 202.

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. That is, in order to protect data written in a magnetic disk device, a write protection switch attached to the magnetic disk device must be turned on. For that reason,
Although it is possible to put any magnetic disk device into a write-protected state, it is not possible to write-protect just any block on any track within the magnetic disk device.

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, if a write instruction is erroneously sent due to a failure of the central processing unit or the like, there is a drawback that it is impossible to prevent data written in the magnetic disk device that is to be protected from being destroyed.

The present invention has been made in view of the above-mentioned conventional circumstances,
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 block number and last block number on a specific track representing a write-protected area of the magnetic disk device sent from the processing unit, and data writing between the central processing unit and the magnetic disk device. /The read operation is performed by driving the data transfer circuit, and after storing the first block number and last block number on a specific track representing the write-protected area sent from the central processing unit in the storage circuit, the read operation is performed by driving the data transfer circuit. When an instruction to write data to an arbitrary block number of an arbitrary track is received, the area of the first block number and the last block number on a specific track represents a write-protected area where the block 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. and a microprogram control circuit that sends data to the device.

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 an embodiment of the present invention.

In FIG. 1, a magnetic disk control device lOO of the present invention is shown.
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 sends an instruction to write data to a magnetic disk device (not shown) through a line 203.
The data transfer circuit 110 is driven through the line 20, and the write data taken in from the central processing unit through the line 200 is transferred to the line 20.
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 receives the first block number and the last block number on a particular track representing a write-protected area from the central processing unit through a line 202. When received, line 204
The block number is stored in the memory circuit 120 through the block number. When the microprogram control circuit 130 receives an instruction to write data to any block on any track of the magnetic disk device from the central processing unit through the line 202, the microprogram control circuit 130 writes the write-protected area stored in the storage circuit 120 through the line 204. The represented block number is read and a comparison is made to see if any block number of any track is within the write-protected area.

The microprogram control circuit 130 connects the data transfer circuit 110 to the data transfer circuit 110 through the line 203 when the area is outside the scolding withering area.
The write data taken in from the central processing unit through line 200 is written to the magnetic disk device through line 201, whereas if it is within the area, a write instruction to a write-protected area is sent from the central processing unit. The report is sent over line 202 to the central processing unit.

As described in detail, according to the present invention, the first block number and the last block number on a specific track representing a write-protected area of a magnetic disk device sent from a central processing unit are stored in a storage circuit. After that, when an instruction to write data to any block number of any track is received from the central processing unit, it is compared whether the block number is within the write-protected area, and if it is outside the area, it is determined that it is normal. If it is inside the area, the data write operation is executed by sending a report to the central processing unit that a write instruction to the write-protected area has been sent from the central processing unit. Even if a write instruction is sent by mistake due to a failure of the central processing unit, etc. to the area of the magnetic disk drive that you want to protect, the data written in the magnetic disk drive that you want to protect is prevented from being destroyed. The effect of being able to do this is obtained.

[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 control 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 data transfer, a storage circuit that stores the first block number and last block number on a specific track representing a write-protected area of the magnetic disk device sent from the central processing unit, and a data transfer circuit that stores data sent from the central processing unit. When a write/read instruction is received, data write/read operations to the magnetic disk device are performed by driving the data transfer circuit, and the first block on a specific track representing a write-protected area sent from the central processing unit is and the final block number are stored in the storage circuit, and when an instruction to write data to any block number of any track is received from the central processing unit, the block number is stored in the storage circuit.Writing is prohibited. It compares whether the first block number and the last block number on a specific track representing the area are within the area, and if it is outside the area, the data write operation is executed normally, but if it is inside the area, the data write operation is executed normally. A magnetic disk control device comprising: a microprogram control circuit that sends a report to a central processing unit that a write instruction to a write-protected area has been sent from the central processing unit.