JPS59165210A - Error correction system - Google Patents

Abstract

PURPOSE:To sample about two error track pointers from an FF which is reset most recently by reading and using a necessary number of stored error track pointers when a shortage of error track pointers occurs during error correcting operation. CONSTITUTION:A PROM5 sends out ''1'' to an AND circuit 6 when the number of generated error track pointers of each track is <=2 at the time of a GCR recording system, and sends out ''1'' similarly when <=1 at the time of a PE recording system. A PROM8 decides on whether the number of error track pointers is deficient or not by the output of an OR circuit 7. When so, the flip- flop 9 is set to sent out an error track pointer read out of an RAM13 to an ECC circuit 18 through the AND circuit 6. When the pointers are still deficient, the PROM8 sets the flip-flop 9 set by a clock again; and the contents of a counter 17 are decreased by one and the RAM13 are read to send out an error track pointer to the ECC circuit 18 through the AND circuit 6 and OR circuit 7.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a magnetic tape control device that controls a magnetic tape device and uses an OCR recording method or a PE recording method.
In particular, there is a shortage of error track pointers (pointers that indicate the track where an error has occurred) that are required when performing error correction.

The present invention relates to an error correction method that performs error correction by employing as many error track pointers as needed starting from the most recently reset error track pointers when correction is impossible.

(b) Prior art and problems When a magnetic tape control device using the OCR recording method reads data from a magnetic tape using a read command, ■ If an error is detected in one trunk out of nine trunks in a data group, ECC is detected. The error can be corrected by the circuit, and if an error is detected in two trunks, it can be corrected by the ECC circuit as well if the error trunk pointer points to the corresponding trunk. However, in the continuous instruction, even if the error trunk pointer is sent once, it will be sent if it is not used for error correction for a certain period of time, so when an error is detected in 2 trunks, the error trunk pointer will be reset, and the error trunk pointer will be reset. Without the trunk pointer, the error cannot be corrected.

In addition, in a magnetic tape control device using the FIE recording method, if an error is detected in one trunk in one byte of data due to a series of commands, the error can be corrected if the error track pointer is set. The disadvantage is that it cannot be corrected if it is not available.

(C) Object of the Invention The object of the present invention is to eliminate the above-mentioned drawbacks by storing up to two error trunk pointers when resetting the error trunk pointer, and in the case of OCR recording method, data errors are If an error trunk pointer is detected across trunks and the number of error trunk pointers is insufficient, among the stored error trunk pointers, the error trunk pointer that has been reset closest is employed until the number of error trunk pointers for two trunks is reached. , perform error correction. In addition, in the case of the PE recording method, when there is no memorized trunk pointer, one of the error trunk pointers that have been reset most recently among the stored error track pointers is used to correct the error (11). It is about providing.

(d) Structure of the Invention The structure of the present invention is to provide a magnetic tape control device that uses an error trunk pointer in order to correct errors that occur when data continues to be transmitted, including means for storing the reset error trunk pointer; Means for reading out the error track pointers stored in the storage means in the order of latest storage, and means for determining whether the number of error track pointers required for error correction is insufficient are provided, If you run out of pointers,
A necessary number of the error track pointers stored in the storage means are read out from the successive output means and used.

(e) Examples of the invention The figure is a block diagram of a circuit showing one embodiment of the present invention.

Flip-flop 1, 2. ．． 3 are respectively set or reset 1' by cent signals or reset signals set by three types of error trunk pointers. The outputs of flip-flops 1, 2, and 3 are sent to FROM5 via OR circuit 4.
to go into. If the number of trunks is 1, for example 9 tracks, 9 circuits are input to the FROM 5. FROM 5 uses a pre-recorded program to check whether the number of error trunk pointers in each track is 2 or less in the case of OCR recording method, and if it is 2 or less, sends 1" to AND circuit 6. In case of PE recording method If it is less than 1, "1" is sent out in the same way. At this time, the fourth output of the OR circuit is simultaneously sent to the OR circuit 7.
If the error trunk pointer is sent to the ECC circuit 18 and the data can be corrected, the error trunk pointer is used. Also, the output of the OR circuit 4 sent to the flip-flop lO is sent to the flip-flop 10 by the clock, and when the error 1-rank pointer is reset, the differential output together with the NOT circuit 11 turns on the AND circuit 12 and outputs RA.
Send to M13. At this time, AND circuit! The output of 2 is OR
The AND circuit 15 is turned on along with the clock via the circuit 14, and the RAM 13 is enabled. At the same time, the flip-flop 16 is set or reset to indicate the address of RAML'3. Therefore, the reset error trunk pointer is stored in the RAM 13. At the same time, a counter 17 indicating the read address of the RAM 13 is incremented together with the output of the flip-flop 9, which will be described later. R'A
If the number of trunks is 9, for example, M13 has a capacity of 2 words of 9 bits, so there are 2 addresses. Flip-flop □10, AND circuit 12.
The same number of NOT circuits 11 as the number of tracks are provided. Also R
The number of outputs of AM13 is the same as the number of trunks, and there are 6 AND circuits.
．． The same number of OR circuits 7 as the number of trunks are also provided.

FROM8 uses a pre-recorded program.
□ Based on the output of the OR circuit 7, it is determined whether the number of error trunk pointers 1 is insufficient. When it is insufficient, set flip-flop 9 and transfer RAM 13.
The error trunk pointers that have occurred one after another are sent to the ECC circuit 18 via the AND circuit 6. However, the counter 17 is synchronized with the center line 1 of the flip-flop 16 in advance so that when the flip-flop 9 is set, the value of the counter 17 indicates the latest write address. If the error trunk pointer is still insufficient, FROM8 sends the flip-flop 9 reset by the clock again, returns the counter 17 by one, reads out the RAM1.3, and executes the AND circuit 6. ECC circuit 1 via OR circuit 7
The error track pointer is sent to 8.

(f) Detailed Description of the Invention As described above, in the case of the OCR recording method, when an error is detected in two tracks and the error track pointer is insufficient, the error track pointer is reset from the nearest one to the second track pointer. It is possible to adopt
Even in the case of the PR recording method, if there is no error trunk pointer, it is possible to use the latest recorded error track pointer, which makes it possible to carry out error correction operations, which has a great effect.

[Brief explanation of drawings]

The figure is a block diagram of a circuit showing one embodiment of the present invention. 1.2,3. ．． 9, 10.16 is a flip-flop, 5
．． 8 is FROM, 13 is RAM, 17 is counter, 18
is an ECC circuit.

Claims (1)

[Claims] To correct errors that occur when data continues to be generated. In a magnetic tape control device using an error trunk pointer, means for storing the reset error track pointer, means for reading the error trunk pointer stored in the storage means in the order of latest storage, and necessary for error correction. means for determining whether the number of error trunk pointers is insufficient, and when there is a shortage of error trunk pointers when executing error correction, the necessary number of error trunk pointers stored in the storage means are continuously stored. An error correction method characterized in that the error correction method is read out from the means and used.