JPS6139262A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To prevent missing of information by providing a gate circuit for information write inhibition and permission at each magnetic head so as to attain command of write inhibition/permission at each magnetic head from a high-order device. CONSTITUTION:When an information write inhibition signal 15 is stored in an information write inhibition/permission signal storage circuit 17, a gate circuit 13 makes an information write command signal 14 ineffective to inhibit information write to a magnetic information disc 10. When a permission signal is stored, since the gate circuit 13 is opened, the information write command signal 14 is made effective and the write of information to the magnetic information disc 10 is permitted via a magnetic head control section 12 and a mangetic head 11. On the other hand, since an information read command signal 18 does not pass through the gate circuit 13, the information read from the magnetic information disc 10 is attained at all times. Thus, missing of information caused by a fault of the high-order device is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a magnetic disk device having a plurality of magnetic heads used as a secondary storage unit of an information processing device, a communication processing device, etc.

(Prior Art) In a conventional magnetic disk device, writing of information can be prohibited or permitted only for a plurality of magnetic heads as a whole, rather than for each magnetic head individually.

In recent years, as the capacity of magnetic disk devices has increased,
There are cases where a single magnetic disk device stores multiple types of information with different attributes.

In such a case, conventional magnetic disk devices have the disadvantage that information that should be prohibited from being rewritten is rewritten due to reasons other than failures in the host device, resulting in information loss.

(Objective of the Invention) The object of the present invention is to provide a gate circuit for inhibiting/permitting information writing for each magnetic head of a magnetic disk device, and to enable a host device to instruct each magnetic head to inhibit/permit information writing. It is an object of the present invention to provide a magnetic disk device which can solve the above-mentioned drawbacks and prevent loss of information.

(Structure of the Invention) In order to achieve the above object, a magnetic disk device according to the present invention has a plurality of magnetic heads and is capable of writing and reading information. A circuit for giving prohibition/permission instructions is provided so that information can be written in units of each magnetic head. ``According to the above configuration, the objects of the present invention are fully achieved.

(Example) Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 81 is a block diagram showing an embodiment of a magnetic disk device according to the present invention.

When writing information to the magnetic information disk 1o, an information write instruction signal 14 is supplied to the magnetic head control section 12 via the gate circuit 13 to instruct information writing.

The information write prohibition permission signal holding circuit 17 holds the information write prohibition signal 15 when it is input, and holds the signal when the information write permission signal 16 is input.

The output of the information write prohibition permission signal holding circuit 17 and the information write instruction signal 14 are ANDed by the gate circuit 13.

Therefore, when the information write prohibition signal 15 is held in the information write prohibition permission signal holding circuit 17, the information write instruction signal 14 is invalidated by the gate circuit 13, and information writing to the magnetic information disk 10 is prohibited.

Furthermore, when the permission signal is held, the gate circuit 1
3 is open, the information write instruction signal 14 becomes valid, and the magnetic head controller 12 and the magnetic head 11
Writing of information to the magnetic information disk 10 is permitted via .

On the other hand, since the information read instruction signal 18 does not pass through the gate circuit 13, information can always be read from the magnetic information disk 10.

By independently supplying information write prohibition signals and permission signals to each magnetic disk unit, writing can be performed in magnetic disk units. Therefore, it is possible to prevent information from being lost due to a failure of a host device or the like.

(Effects of the Invention) As described in detail above, the present invention has the effect of preventing information loss due to a failure of a host device or the like by making it possible to inhibit information writing in units of information magnetic heads.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device according to the present invention. lO...Magnetic information disk 11...Magnetic head 12...Magnetic head control section 13...Gate circuit 14...Information write instruction signal 15...Information write prohibition signal 16...Information write permission Signal 17...Information write prohibition/permission signal holding circuit 18...
・Information reading instruction signal Patent applicant: NEC Corporation Representative, Patent attorney: Hisashi Inoro Figure 1

Claims (1)

[Claims] In a magnetic disk device that has a plurality of magnetic heads and is capable of writing and reading information, a circuit is provided for instructing each of the magnetic heads to prohibit or permit writing of information, A magnetic disk device characterized in that writing can be prohibited or permitted.