JPH01260674A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent the destruction and the reading error of a format by comparing the data length of a key part and a data part at the time of reading/ writing a count part with the data length of the writing/reading to the key part or the data part and informing to a host device when they do not coincide. CONSTITUTION:A storing part 1 stores the data length of the key part and the data part of the count part in which the writing/reading is executed and a selecting part 2 selects the data length of the key part or the data length of the data part outputted from the storing circuit 1. A counter 1 counts up the unit data of the key part of the data part one by one according to the writing/reading operation thereof and counts the number of times of the operations as the data length. In a comparing means 3, the output of the selecting circuit 2 is compared with the output of the counter 4 and when both the data do not coincide, the discord of the data length is informed to the host device. Thereby, the destruction of the format or the generation of the data error can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the data length of data stored in a magnetic disk device, and particularly to its writing/reading method (prior art). A unit record consists of a count section and a data section, or a count section, a key section, and a data section. The data length of the count section is a fixed length independent of the cylinder address, head address, and record number.

However, in the key section and the data section, the data length differs depending on the cylinder address, head address, and record number, and each data length is written as information in the count section of the same record.

Normally, a magnetic disk drive continues writing to the count section, key section, and data section during the period when the write signal sent from the host device is active, and during the period when the read signal sent from the host device is active. The device is configured to continue the read operation.

(Problems to be Solved by the Invention) In the conventional magnetic disk device described above, writing/reading signals from the host device are active.
Read operation continues. For this reason, failure of the host device,
If the write signal does not match the data length to be written due to a bug in the /W operation, the format will be destroyed, and if the read signal does not match the data length to be read, The disadvantage is that read errors occur.

An object of the present invention is to: When writing/reading the count section,
Compare the data length of the key part and data part with the data length of writing/reading to the key part or data part, and if the two do not match, report the fact that the data lengths do not match to the host device, thereby eliminating the above drawbacks. It is an object of the present invention to provide a magnetic disk device configured to remove data and prevent format destruction and data errors.

(Means for Solving the Feedback Level) A magnetic disk drive according to the present invention includes a storage circuit, a selection circuit, a counter, and a comparison means.

The memory circuit is for storing the data length of the key part and data part of the count part data to be written/read.

The selection circuit is for selecting the data length of the key section or the data length of the data section output from the storage circuit.

The counter is used to count up one by one by write/read operations of unit data in the key section or data section, and count the number of the above operations as the data length.

The comparison means is for comparing the output of the selection circuit and the output of the counter and reporting a discrepancy in data length.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device according to the present invention. In FIG. 1, 1 is a storage circuit, 2 is a selection circuit, 3 is a comparison circuit, 4 is a counter, and 5 is an N
OT gate, 6. F is an AND gate, 8 is an OR gate.
It is a gate.

At the time of writing, count section write/read data is input to the storage circuit 1 via the signal line 9. Therefore, the memory circuit 1 stores the data of the key section and the data section. At the time of reading, the memory circuit 1 sends out the data length of the key section onto the signal line 12, and sends out the data length of the data section onto the signal line 13.

When the select signal on the signal line 10 becomes t 1 # during writing/reading to the key section, the selection circuit 2 selects either the key section data length on the signal line 12 or the data section data length on the signal line 13. The selected data length is sent onto the signal line 14.

The write/read signal from the signal line 11 becomes the key 1# when writing to/reading from the key section or the data section. While the write/read signal is 11g, the counter 4 counts up by 1 for each unit of data and sends a count signal onto the signal line 1S.

The comparison circuit 3 compares the count number s sent from the counter 4 onto the signal line 15 and the data length sent from the selection circuit 2 onto the signal line 14 .

If the value of the data length sent out on the signal @14 is larger than the value of the count signal sent out on the signal line 15, the judgment value sent out on the signal line 1f from the comparison circuit 3 becomes %11. . On the other hand, if the value of the data length sent out on the signal line 14 is smaller than the value of the count signal sent out on the signal line 15, the judgment value sent out on the signal line 16 from the comparison circuit 3 is %lI. Become.

If the write/read signal on signal line 11 is %1# and the judgment value on signal line 16 is 11#, the output of AND gate 6 will be %11. On the other hand, when the write/read signal on signal line 11 is OF, the judgment value on signal line 17 is %1F.
If so, the output of AND gate 7 becomes Kame 1#.

If either the output of AND gate 6 or F is 1#, or both are %IN, the signal sent from OR gate 8 onto signal line 18 will be %1N.

Next, the sequence of the above operations will be sequentially explained.

Writing/reading to the key section or data section [7] Before performing the operation, read the count section once.
The data in the count section is applied to the memory circuit IK via the signal line 9, and the data lengths of the key section and data section are stored in the memory circuit 1.

Next, when performing a write/read operation to the key section or the data section, the data length of the key section or the data length of the data section is selected by the selection circuit 2 under the control of the select signal (M) on the signal line 10, and 14.

When a write/read operation to the key section or data section is started, the write/read signal on the signal line 11 becomes %II.
Then, counter 4 starts counting up.

Here, if the write/read operation ends with the data length of the key part or the data length of the data part shorter,
The judgment signal output on signal line 1) becomes turtle 11, and signal line 1
The write/continue output signal above 1 becomes %ON. For this reason,
Both input signals of AND gate 7 become 11 #,
The output of AND gate 7 is %1#7 and OR gate 8
The output from the signal line 18 to the signal line 18 becomes %1#.

When the write/read operation is longer than the data length of the key section or the data section, the determination signal output on signal line 16 becomes 11', and the write/read signal on signal line 11 becomes 1111. Therefore, the output of the AND gate 6 becomes tIN, and the output from the OR gate 8 onto the signal line 18 becomes %11.

The output signal on the signal line 18 is sent to the host device, and it is reported that the data lengths do not match.

(Effects of the Invention) As explained above, the present invention compares the data length of the key part and the data part with the data length of the key part or the data part when writing/reading the count part. , when the above two do not match, by reporting the data mismatch to the host device, the host device can retry, eliminating format corruption and read errors, improving reliability. There is an effect that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device according to the present invention. 1...Memory circuit 2...Selection circuit 3...Comparison circuit 4...Counter 5...NOT circuit 6.7...AND gate 8...OR gates 9-18...Signal line

Claims (1)

[Claims] a memory circuit for storing the data length of the key part and data part of the count part data to be written/read; and the data length of the key part output from the memory circuit;
Alternatively, a selection circuit for selecting the data length of the data section and a writing/reading operation of unit data of the key section or the data section are used to count up one by one, and the number of the operations is counted as the data length. 1. A magnetic disk drive comprising: a counter for the selection circuit; and comparison means for comparing the output of the selection circuit with the output of the counter and reporting a discrepancy in the data length.