JPH02206063A - Magnetic disk controller - Google Patents

Abstract

PURPOSE:To execute a control by two sets or more of host devices without being aware of a data area by writing a write permitting bit corresponding to each of two sets or more of host devices in the part of a flag in a sector ID at the time of format to a magnetic disk device. CONSTITUTION:When a format instruction to a magnetic disk device 200 is inputted to a magnetic disk controller 100 from a central processing unit 400 or 500, data is read out of the address of a main storage device 600 instructed from the central processing unit 400 or 500 and formatted as an ID to the magnetic disk device 200. In this case, in the case of permitting write in a bit position corresponding to each system as the value of a flag byte written in the main memory device 600, a value '0' is written. A flag part in the ID which is read out of the magnetic disk device 200 is compared with a write permitting bit inputted from a write level memory circuit 60 by a flag comparator 50, by which two sets or more of host devices can execute a control without being aware of each data area by utilizing one set of magnetic disk controller.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic disk control device used in an information processing device.

2. Description of the Related Art Conventionally, as a method for checking permission for a write operation on a fixed sector type magnetic disk device having a sector ID for identifying each sector, a method of checking permission for a write operation to a sector requested by a software driver part is performed. A first method of checking based on map information of the magnetic disk device expanded on the memory, and a second method of turning on the protect switch of the magnetic disk device to write-protect the entire magnetic disk device are known.

Problems to be Solved by the Invention However, in the first method of the magnetic disk control device described above, if there are two or more host devices and each host device uses different software, the map information of the magnetic disk devices is Since the management methods are different, there is a drawback that it is not possible to check whether a write operation can be performed on the requested sector.In the second method mentioned above, when the protect switch of the magnetic disk device is turned on, the entire magnetic disk device is unable to perform write operations. There was a drawback that it was not possible to set write protection to only a portion of the data.

The present invention has been made in view of the above-mentioned conventional situation,
SUMMARY OF THE INVENTION Therefore, 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 provides a fixed sector type magnetic disk device having a sector ID for identifying each sector. Write a write permission bit corresponding to each upper-level device to determine whether or not a write operation to the normally writable data section is possible for each of two or more upper-level devices in the flag part of a writing means, a storage means for storing the write permission bit for which higher-order device is to be checked according to a command from the higher-order device, and
Comparing means for reading the flag part in D and comparing the position where the write permission bit is set and the bit position of the write permission bit to be checked stored in the storage means, and the comparing means and means for determining, as a result of the comparison, whether or not a write operation to a normally writable data portion in the same sector is possible.

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

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

In FIG. 1, a magnetic disk control device 1 according to the present invention
00 is bus control circuit 10, magnetic disk control circuit 20
, a microprocessor 30, a flag comparison circuit 50, and a write level storage circuit 60.

Further, the magnetic disk controller v too controls the magnetic disk 2
00, and is also connected to the central processing units 400 and 500 and the main storage device 600 via the bus 300.

The operation of the magnetic disk control section configured in this way is as follows. The magnetic disk device 200 is connected to the magnetic disk control device 100 from the central processing unit 400 via the bus 300.
When a formatting command is input to the microprocessor circuit 30, the microprocessor circuit 30 outputs a seek command to the designated cylinder from the central processing bag W400 to the magnetic disk device 200 via the magnetic disk control circuit 20. When the seek operation is completed, the microprocessor circuit 30
Data is read from the address of the main storage device 600 instructed by the central processing unit 400, and the magnetic disk control circuit 2
0, add 5YNC bytes and CRC shown in Figure 2,
The data read from the main storage device 600 is written and formatted as a FLAG byte, cylinder number, track number, and sector number in the magnetic disk device 200 as an ID section. As the value of the FLAG byte written to the main storage device 600, the central processing bag! 4. To allow writing to a predetermined bit position in oO, use the value ``'1''
', and when only reading is permitted, write the value "0".

In this way, when the formatting operation for the central processing unit 400 is completed, the central processing unit 400 sends the data to the bus 3.
Suppose that a write command is input after the magnetic disk control device 100 executes a command to set a predetermined bit position corresponding to the central processing unit 400 in the write level storage circuit 60 via 00. , the microprocessor circuit 30 connects the central processing unit 400 to the magnetic disk device 200 via the magnetic disk control circuit 20.
Outputs a seek command to the specified cylinder.

When the seek operation is completed, the microprocessor circuit 30
is a magnetic disk drive W for the magnetic disk control circuit 20.
A search operation for data read from 2O0 is started. When the 5YNC byte shown in FIG. 2 is detected by the magnetic disk control circuit 20, the magnetic disk control circuit 20
Start AG byte detection operation.

The magnetic disk control circuit 20 detects the FLAG byte,
When the value is output to the flag comparison circuit 50, the two-flag comparison circuit 50 starts comparing the input FLAG byte data with the write permission pins 1 to 1 inputted from the write level storage circuit 60. The results compared by the flag comparison circuit 50 are notified to the magnetic disk control circuit 1 ¥820,
As a result of the notification, if the magnetic disk control circuit 20 is in a state in which writing is not permitted, it marks the sector as J-sell, continues the search operation for the missing sector, and returns to a state in which writing is permitted. If so, the magnetic disk control circuit 20 continues to compare the read data from the magnetic disk device 200 with the cylinder number, track number, and sector number and to check the CRC data. As a result, the microprocessor circuit 30 is the target sector;
If the CRC is "OK", a write operation to the data section is started; otherwise, the sector is skipped and the search operation for the next sector is continued.

As described in detail, by employing the magnetic disk control device of the present invention, when two or more host devices use one magnetic disk device, they can control each other without being aware of each other's data areas. You can get the desired effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure shows an example of the format of sector D. DESCRIPTION OF SYMBOLS 10... Bus control circuit, 20... Magnetic disk control circuit, 30... Microprocessor circuit, 5o... Flag comparison circuit, 60... Write level storage circuit, 100
...Magnetic disk control device, 200...Magnetic disk device, 300...Bus, 400.500...Central processing unit, 600...Main storage device Patent applicant NEC Corporation Representative Patent attorney Master Yutabe Kumagai

Claims (1)

[Claims] When formatting a fixed-sector type magnetic disk device that has a sector ID to identify each sector, the flag part in the sector ID corresponds to each of two or more host devices, and the data part that can be written normally is written. A writing means for writing a write permission bit corresponding to each host device to determine whether a write operation is possible or not, and a memory for which write permission bit is to be checked for which host device based on a command from the host device. a storage means, and a comparison means for reading a flag part in a sector ID during a write operation and comparing the position where the write permission bit is set and the write permission bit position to be checked stored by the storage means; and means for determining whether or not a write operation to a normally writable data portion in the same sector is possible as a result of the comparison by the comparison means.