JPS6128191B2 - - Google Patents

Description

[Detailed Description of the Invention] Conventional methods for checking the sector length include counting the number of recording bits between sector marks and determining that the number is normal if the number is a predetermined number, and counting the number of recording bits between sector marks. Record it and
There was a method in which an up-down counter was used to compare the number of bits from a sector mark to a signal recorded in the middle with the number of bits from then on to the sector mark, and if they were the same, the sector length was determined to be normal.
However, in the former method, there is a problem that the longer the sector length, the more the number of counts increases, resulting in a huge number of counters. Also, the latter method has the same problems as the former. Additionally, the sector length must be an even number.

An object of the present invention is to make it possible to always use the same detection method without affecting the check circuit even if the sector length is set arbitrarily.

The feature of the present invention is that, in addition to the sector mark, a specific mark is recorded a certain number of bits before the sector mark, and the number of bits from reading that specific mark to the sector mark is counted. If the number of bits between the set sector mark and the specified mark match, the detected sector mark is normal; if the number of bits differs, it is checked that it is abnormal.

To explain one embodiment of the present invention, 1 is a sector mark to be checked, and the sector length (interval) is arbitrarily set depending on the purpose of use of the device. 2 is a check mark provided for checking the sector mark, and is a mark to be detected a certain length before the sector mark. 3 is a master clock that is always available for synchronizing recorded data. 4 is a flip-flop which is set by sector mark 1 and reset by check mark 2; A counter 5 is reset by the output of the flip-flop 4, and counts the number of master clocks existing within a fixed length between the sector mark 1 and the check mark 2. A circuit 6 reads the contents of the counter 5 when a sector mark is input, and checks whether the contents match a predetermined number of bits.

Now, when the flip-flop 4 is reset by the check mark 2, the counter 5 is also reset by its output, and at the same time as its contents are cleared, it starts counting the number of the master clock 3. Next, when sector mark 1 arrives, the flip-flop 4 enters the set state, and the check circuit takes in the number counted by the counter 5 and checks whether it matches a predetermined number. , determines whether or not there is an abnormality in the sector signal, and outputs the result as a check output signal.

As described above, according to the present invention, even if the sector length differs depending on the device, the counter input is determined by how many bits earlier the check mark is recorded than the sector mark. can be the same, and the circuit is simple.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram for explaining an embodiment of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention. 4...Flip-flop, 5...Counter, 6
...Check circuit.

Claims (1)

[Claims] 1. In a rotating magnetic memory device having a clock track for generating a plurality of plural types of sector clocks following an index clock, in addition to the sector mark, a certain number of bits before the sector mark is added to the clock track. A sector length check method characterized in that a check mark is provided on the sector mark and the sector length is checked by counting the number of bits within a fixed length between the sector marks.