JPH0317802A - Write control circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To enhance reliability by reducing the probability to lose data completely by writing the data with the same content on two parts on a disk medium. CONSTITUTION:A write circuit 1 writes the data on the disk medium 8 based on a write gate signal 10 and a write data signal 11. Delay circuits 3 and 4 send the signals 10 and 11 to a write circuit 2 by delaying by constant time. The circuit 2 performs the write on the medium 8 based on those delayed signals. Therefore, the data with the same content can be written on the two parts on the medium 8. Consequently, the probability to destroy the data simultaneously can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a write control circuit for a magnetic disk device used as an external storage device in a computer system or the like.

[Prior Art] Conventionally, this type of write control circuit has performed write control only to a head selected from the outside.

[Problems to be Solved by the Invention] The conventional write control circuit described above causes only one head selected by an external signal to perform a write operation. Therefore, the written data is
To check whether data has been erroneously stored due to a defect in the disk medium, a checksum such as CRC or ECC is performed to compare the data before writing with the data read. However, since the write operation and the read operation are performed by one head, it is necessary to wait until the disk medium rotates once before reading the data written by the head. This type of confirmation method has the disadvantage that the confirmation takes too much time. As a result, the processing speed of the magnetic disk device and the system including the magnetic disk device is reduced. Also,
Another drawback is that data is written to only one location on the disk medium, so if that location is destroyed, the data will be lost forever.

An object of the present invention is to provide a write control circuit for a magnetic disk device that is highly reliable in terms of data storage.

[Means for Solving the Problems] In order to achieve the above object, a write control circuit for a magnetic disk device according to the present invention has the following features.

That is, the present invention provides a write control circuit for a magnetic disk device having two or more heads for writing and reading data, including: a first write circuit for writing data with an externally selected head; a second write circuit for writing data with a head that is not externally selected; and a write gate signal and a write data signal externally applied to the first write circuit that are delayed for a certain period of time to write data to the second write circuit. It is characterized by having a delay circuit for sending data to.

[Operation] Upon receiving the write gate signal and the write data signal, the first write circuit writes data to the disk medium. The delay circuit uses the same write gate signal and write data. It receives these signals, delays these signals for a certain period of time, and sends them to the second write circuit. The second write circuit writes data to the disk medium based on the delayed write gate signal and the write data signal.

As a result of the above, data with the same content is written to two locations on the disk medium. The probability that these pieces of data will be destroyed at the same time is extremely low, making the magnetic disk drive a highly reliable device for data storage.

【Example] Next, embodiments of the invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a write control circuit according to an embodiment of the present invention.

This write control circuit includes a first write circuit 1, a second write circuit 2, a first head 5 driven by the first write circuit 1, and a first head 5 driven by the second write circuit 2. It has two heads 6, a first delay circuit 3 that delays the write gate signal 10, and a second delay circuit 4 that delays the write data signal 11.

Here, the surface of the disk medium 8 facing the first head 5 is referred to as a first side A, and the surface of the disk medium 8 facing the second head 6 is referred to as a second side B. Note that the disk medium 8 is rotated by the motor 7.

Next, an information write operation by this write control circuit will be explained. FIG. 2 is a time chart diagram for explaining the circuit operation of the write control circuit and a format diagram written on the disk medium 8.

Now, consider the case where the host device W1 (controller) (not shown) selects the first head 5 and writes data to the first side A{1111. After confirming the ID part of the format written in the first side A, the host device makes the write gate signal 10 active (LOW), and at the same time makes the write data signal 11 valid (VALI).
D) Send data. As a result, the first write circuit 1 drives the first head 5 to write data into the data section of the first side A. The first delay circuit 3 delays the write gate signal 10 by a certain time t, and sends it to the second write circuit 2 as a delayed write gate signal 12. Further, the second delay circuit 4 also delays the write data signal 11 by a certain time t, and sends it to the second write circuit 2 as a delayed write data signal 13. As a result, the second write circuit 2 can write data to the second side B with a delay of a certain time t relative to the write operation of the first write circuit 1.

Next, the operation of reading data written on the disk medium 8 as described above will be explained.

FIG. 3 is a time chart when reading data written by this write control circuit. A format diagram written on the disk medium 8 is also shown for reference.

The side selection signal 20 selects one of the first side A and the second side B of the disk medium 8. Then, the data is read out using the read signal 21.

The side selection signal and the read signal are generally called side select and read data, respectively, in flexible disk drives and the like.

Here, it is assumed that data n on the first side A has been destroyed by some kind of original prisoner. In this case, since data n cannot be directly read out, data N having the same content as data n (data N is written on the second side B) is read out. The controller recognizes the ID corresponding to data n and switches the side selection signal 20.

As a result, undestroyed data N is read out by the read signal 21.

In the above read operation, the reason for writing data to the second side B with a delay of time t is as follows.

For example, if the disk medium is replaceable, such as a flexible disk device, data formatting is required to enable data exchange with other flexible disk devices.・The format is defined.

Furthermore, since data is only written on one side of the disk medium, the 10th section followed by the <GAP section alone does not provide enough time to select a head. Therefore, it is necessary to write the data to the second side B with a delay of time t.

In addition, in a flexible disk device that writes data on both sides of a disk medium, there is always a relative positional error between the head on the first side A side of the disk medium and the head on the second side B side. do. Therefore, when a certain flexible disk device simultaneously writes data to the first side A and second side B of a disk medium, and this disk medium is read by another flexible disk device, the data on the first side A side is 1
The beginning part of the data on the second side B that corresponds to this data may overlap part D. In such a case, as described above, it is impossible to read the data after confirming the ID part. Therefore, it is necessary to write the data to the second side B with a delay of time t.

[Effects of Hatsu-4] As explained above, when writing data to a disk medium, this Hatsukawa first writes data to the disk medium using the first writing circuit.

Then, data having the same content as the data written by the first write circuit is delayed by a delay circuit, and then written by the second write circuit.

This has the following effects.

When writing data to a disk medium, a write error may occur due to dust or the like existing on the disk medium. However, at the same time, the probability that such a write error will occur at two locations on the disk medium is extremely low.

Therefore, the present invention can improve the processing capacity of the entire magnetic disk drive system.

Furthermore, after writing, the data on the disk medium may be destroyed by some kind of prisoner, but since the same data has been written to two locations on the disk medium, there is no guarantee that the data will be completely lost. , extremely low. the result,
This starting point makes it possible to create a highly reliable magnetic disk drive system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a time chart diagram for explaining the circuit operation of the write control circuit of this embodiment, and a format diagram written on a disk medium. These are a time chart diagram when reading data written by one write control circuit in this embodiment, and a format diagram written on a disk medium. 1... First write concave path 2... Second write path 3... First delay circuit 4... Second delay circuit 5... First head 6... Second head 8...Disk medium 10...Write gate signal 11...Write data signal l2...Delayed write gate signal 13...Delayed write data signal

Claims (1)

[Claims] In a write control circuit for a magnetic disk device having two or more heads for writing and reading data, a first write circuit for writing data with an externally selected head; a second write circuit for writing data with a head that is not externally selected; and a write gate signal and a write data signal externally applied to the first write circuit that are delayed for a certain period of time to write data to the second write circuit. 1. A write control circuit for a magnetic disk device, comprising a delay circuit for sending data to.