JPH02201562A - 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 head number is received from a central processing unit after a first head number and a last head 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 head 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.

2. Description of the Related Art Conventionally, the method for protecting data written in this type of magnetic disk device was to turn on a write protection switch attached to the magnetic disk device. Therefore, although it is possible to write-protect any magnetic disk drive, it is not possible to write-protect only any track within the magnetic disk drive.

Problems to be Solved by the Invention The method for protecting the data written in the conventional magnetic disk drive described above is only to turn on the write protection switch attached to the magnetic disk drive. For this reason, it is not possible to write to only the arbitrary Wi area in the magnetic disk device that is performing the data writing operation, so the data in the magnetic disk device that is performing the data writing operation cannot be protected from writing. There is a drawback in that when a write instruction is sent to an area to be protected by mistake 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 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 Data writing/reading operations between the central processing unit and the magnetic disk device are performed by a storage circuit that stores the first head number and the last head number representing the write-protected area of the magnetic disk device sent from the processing device. By driving the transfer circuit, the first head number and the last head 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 head number. When received, the head number is compared to see if it is within the area of the first head number and the last head number representing the write-protected area stored in the storage circuit, and if it is outside the area, the data is correctly read. A microprogram control circuit that sends a report to the central processing unit that a write instruction for a write-inhibited area has been sent from the central processing unit when a write operation is executed within the write-protected 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 an embodiment of the present invention.

In FIG. 1, the magnetic disk control device of the present invention! 100
Gi, 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 written from the magnetic disk device through line 201. This is done by sending read data over line 200 to the central processing unit.

When the microprogram control circuit 130 receives the first head number and the last head number representing the write-protected area from the central processing unit through the line 202, the microprogram control circuit 130 stores the head numbers in the storage circuit 120 through the line 204. Microprogram control circuit 130 is connected to line 20 from the central processing unit.
When an instruction to write data to an arbitrary head number of the magnetic disk device is received through line 204,
The head number representing the write-protected area stored in the memory circuit 120 is read out through the memory circuit 120, and a comparison is made to see if any head number is within the write-protected area. The microprogram control circuit 130 drives the data transfer circuit 110 through a line 203 when the result of comparison is outside the area, and writes the write data taken in from the central processing unit through a line 200 to the magnetic disk device through a line 201. On the other hand, if it is within the area, a report indicating that a write instruction to the write-protected area has been sent by the central processing unit is sent via line 202.
to the central processing unit.

Effects of the Invention As explained above, according to the present invention, after storing the first head number and the last head number representing the write-protected area of the magnetic disk device sent from the central processing unit in the storage circuit, the central processing When an instruction to write data to a given head number is received from the device, it is compared to see if the head number is within the write-protected area, and if it is outside the area, the data write operation is executed normally; In the case of , the data in the magnetic disk device that is performing the data write operation is deleted 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 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 an 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 multiple magnetic disk units, data transfer of write/read data between the central processing unit and the magnetic disk units. a data transfer circuit that performs this, a storage circuit that stores the first head number and last head 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. At this time, data writing/reading operations for the magnetic disk device are performed by driving the data transfer circuit, and the first head number and the last head number indicating the write-protected area sent from the central processing unit are sent to the storage circuit. After the track number is stored, when receiving a data write instruction for a given head number from the central processing unit, the track number is stored in the storage circuit within the area of the first head number and the last head number representing a write-protected area. If it is outside the area, the data write operation is executed normally, but if it is inside the area, the central processing unit reports that a write instruction to a write-protected area has been sent from the central processing unit. What is claimed is: 1. A magnetic disk control device comprising: a microprogram control circuit that sends data to a microprogram control circuit;