JPH0814935B2 - Magnetic tape unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A magnetic tape device for performing data compression, recording, and decompressing data after reproduction, and an object thereof is to improve data compression efficiency and substantially improve data recording density of a magnetic tape medium. In a magnetic tape device that compresses a data block, which is block data, records it on a magnetic tape medium and decompresses the compressed data block reproduced from the magnetic tape medium to obtain the original data block. Creating means for counting the data amount of each data block to create block data amount information, adding means for compressing each data block and storing it in a buffer, and adding the block data amount information to each, The number of blocks in which the data amount of the data blocks stored in the buffer is accumulated and counted, and the accumulated count value exceeds a predetermined value. A recording means for continuously adding the block data amount information and recording the compressed data block read from the buffer on the magnetic tape medium, and the compressed data block continuously reproduced from the magnetic tape medium. A dividing unit that divides each compressed data block based on the block data amount information added to each, and is configured to decompress each divided compressed data block to obtain the original data block.

[Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape device, and more particularly to a data recording / reproducing method of a magnetic tape device for compressing data for recording and reproducing and then expanding data.

In a magnetic tape device, it is desired to increase the amount of data recorded per magnetic tape medium.

[Conventional technology]

Conventionally, in order to increase the amount of data recorded per roll of the magnetic tape medium, the tape length is lengthened. Increase the recording density. Inter-block gap (IBG) is being shortened.

FIG. 4 shows a conventional recording data format. In the figure, on the magnetic tape medium 10, a data block (DB) 11a,
11b and 11c are recorded with the IBG12 interposed therebetween. Each data block consists of all “1” pattern 13 indicating the start of data and data
It is composed of 14, a residual character 15, and an entire "1" pattern 16 indicating the end of data. The residual character 15 is a modulo 14 (MOD14) for data check calculated from the number of bytes of the data 12, and a block identification number (BLOCK I
D), a cyclic redundancy check code (CRC) for checking data 12.

[Problems to be Solved by the Invention]

Each of the above-mentioned methods of increasing the data recording amount has reached the technical limit, and the data block DB
Data compression of each of the data 14 of 11a to 11c is in progress.

However, when the data 14 is compressed, the length of the data blocks 11a to 11c on the magnetic tape medium 10 becomes shorter, and in some cases, shorter than the length of the IBG 12 (for example, 2 mm).

In other words, there is a problem that the ratio of IBG, which is a portion on the magnetic tape 10 where data is not recorded, increases, the data compression efficiency deteriorates, and the tape recording density decreases substantially.

The present invention has been made in view of the above points, and an object of the present invention is to provide a magnetic tape device that improves data compression efficiency and substantially improves the data recording density of a magnetic tape medium.

[Means for solving the problem]

In a magnetic tape device that compresses a data block that is block data and records it on a magnetic tape medium, and decompresses a compressed data block reproduced from the magnetic tape medium to obtain the original data block, Creating means for counting the data amount of the data block to create block data amount information, adding means for compressing each data block and storing it in a buffer, and adding each block data amount information, and storing in the buffer Data amount of the data blocks to be accumulated is counted, the block data amount information is added by the number of blocks whose accumulated count value exceeds a predetermined value, and the compressed data blocks read from the buffer are continuously recorded on the magnetic tape medium. The recording device and the compressed data block continuously reproduced from the magnetic tape medium are transferred to the compressed data block. A dividing unit that divides each compressed data block based on the block data amount information added to each data block, and decompresses each divided compressed data block to obtain the original data block.

[Action]

In the present invention, since a plurality of compressed data blocks are continuously recorded on the magnetic tape medium, the ratio of recording the IBG on the magnetic tape medium is reduced, the data compression efficiency is improved, and the tape recording density is substantially increased. improves. Further, since each compressed data block is stored with the block data amount information added thereto, each compressed data block can be divided according to the block data amount information during reproduction.

〔Example〕

 FIG. 1 shows a block diagram of a recording system of the apparatus of the present invention.

In the figure, the host device 20 supplies data, a write start signal, and a write stop signal from terminals 20a, 20b, 20c, respectively. The data compression circuit 21 compresses the supplied data using, for example, a run length code, and the compressed data is supplied to the buffer 22, where it is temporarily stored and then stored in the data section buffer 23 and the CRC calculation circuit 24.

The byte counter 25 counts the number of bytes of the compressed data stored in the buffer 22 after the start of the input of the H-level write start signal, and when the write stop signal comes in, the count value is a byte count creation circuit 26 and the MOD14 counter. 27 Supply to each and reset. Further, the byte counter 28 cumulatively counts the number of bytes of the compressed data stored in the buffer 22 when the H-level write start signal is input, and when the cumulative count value exceeds a preset maximum value, it is at the H level. Maximum value detection signal of AND circuit
It is supplied to 29 and resets itself when the start signal stops coming after the output of this maximum value detection signal.

The MOD14 counter 27 is a 14-ary counter that obtains the value of the modulo 14 from the count value of the byte counter 25, and supplies the obtained value of the modulo 14 to the residual character creating circuit 31 and the padding "0" circuit 32. The padding "0" circuit 32 generates "0" from the value of the modulo 14 to make the number of bytes of the compressed data a multiple of "14" and supplies it to the residual character circuit 31.

The CRC calculation circuit 24 generates a CRC from the compressed data supplied from the buffer 22 and supplies it to the residual character circuit 31. Further, the block ID counter 33 counts up at the start of the incoming write start signal to generate a serial block identification number (BLOCKID) and supplies it to the residual character circuit 31.

The byte count creating circuit 26 creates a byte count for recording the count value supplied from the byte counter 25, that is, the number of bytes of each data block on the magnetic tape medium, and supplies the byte count to the modulating circuit 35. Residual character circuit 31
Is the modulo 14 value from the MOD14 counter 27 and block I
Block identification number from D counter 33 and CRC calculation circuit 24
A residual character to be recorded on the magnetic tape medium is created from the CRC of the above, and "0" from the padding "0" circuit 32 is added and supplied to the modulation circuit 35.

The AND circuit 29 outputs the H level signal when the write stop signal is supplied while the H level signal is supplied from the byte counter 28, that is, when the write stop signal rises after the byte count number exceeds the maximum value. The signal is supplied to the IBG creating circuit 37, and the IBG creating circuit 37 is started by this H level signal to create the IBG signal, and the modulating circuit 3 is generated for a predetermined time.
Supply to 5.

The modulation circuit 35 has all "1" patterns created by all "1" creation circuits 36, the byte count of each data block from the byte count creation circuit 26, the compressed data from the data part buffer 23, and the residual character creation circuit 31. Of the residual character, all "1" patterns from all "1" creation circuit 36, and IBG from all IBG creation circuit 37 are sequentially modulated and output from terminal 38, and this modulated signal is recorded on the magnetic tape medium. To be done.

Byte counter 25 and byte count creation circuit above
26 corresponds to the creating means, the modulating circuit 35 corresponds to the adding means, and the byte counter 28, the AND circuit 29, and the modulating circuit 35.
And the IBG creation circuit 37 corresponds to the storage means.

As a result, as shown in FIG. 2, after recording all "1" patterns 41 indicating the start of data block recording on the magnetic tape medium 40, a compression consisting of a byte count 42, compressed data 43 and a residual character 44 is performed. Data block 45
a, 45b, 45c are recorded, all "1" patterns indicating the end of data block recording are recorded, and IBG47 is further recorded.

 FIG. 3 shows a block diagram of the reproducing system of the device of the present invention.

In the figure, a reproduction signal from the magnetic tape medium 40 enters the terminal 50 and is demodulated by the demodulation circuit 51. Here, the byte count 42 reproduced from each of the compressed data blocks 45a, 45b, 45c is supplied to the byte count register 52, the data (compressed data) 43 is supplied to the data part buffer 53, and the residual character 44 is the residual character. It is supplied to the discrimination circuit 54.

The compressed data stored in the data section buffer 53 is expanded by the data expansion circuit 56 through the buffer 55 and supplied to the terminal 20a of the host device 20. The byte counter 57 counts the number of bytes of the compressed data stored in the buffer 55 when the read start signal of H level is supplied from the terminal 20d of the host device 20 and compares it with the byte count of the byte count register 52. The compressed data is stored in the buffer 55 until The byte count register 52 and the byte counter 57 described above correspond to the dividing means. MOD1
The 4 counter 58 obtains the value of the modulo 14 from the count value of the byte counter 57 and supplies it to the MOD 14 check circuit 59, and a comparison check is made with the value of the modulo 14 discriminated from the residual character 44 reproduced here. Also, CR
The C arithmetic circuit 60 calculates the CRC from the compressed data output from the buffer 55.
Is generated and compared with the CRC discriminated from the reproduced residual character 44 to check.

The block ID counter 61 counts the rising of the read start signal and supplies it to the block ID check circuit 62.
A comparison is made with the block identification number discriminated from the residual character 44 reproduced here. The check results of the MOD14 check circuit 59, the CRC check circuit 60, and the block ID check circuit circuit 62 are notified to the higher-level device 20 and used to judge whether or not the correct reproduction is performed.

As described above, since the plurality of compressed data blocks 45a to 45c are continuously recorded on the magnetic tape medium 40, the ratio of recording the IBG47 on the magnetic tape medium is reduced, the data compression efficiency is improved, and the tape is substantially reduced. Recording density is improved. Further, since each compressed data block 45a to 45c is recorded with a byte count 42 added as block data amount information, each compressed data block 45a to 45c is reproduced at the time of reproduction.
Can be divided according to the byte count 42, and there is no restriction on the data compression method, and any compression method may be used.

〔The invention's effect〕

As described above, according to the magnetic tape device of the present invention, the data compression efficiency is improved, the substantial data recording density of the magnetic tape medium is improved, and it is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording system of the present invention device, FIG. 2 is a diagram showing a recording data format of the present invention, FIG. 3 is a block diagram of a reproducing system of the present invention device, and FIG. 4 is conventional recording data. It is a figure which shows a format. In the figure, 20 is a host device, 21 is a data compression circuit, 24 is a CRC calculation circuit, 25, 28 and 57 are byte counters, 26 is a byte count creation circuit, 27 and 58 are MOD14 counters, 31 is a residual character creation circuit. , 32 is padding "0" circuit, 33,61 is block ID counter, 35 is modulation circuit, 36 is all "1" making circuit, 41,46 is all "1" pattern, 42 is byte count, 43 is data, 44 is a residual character, 45a to 45c are data blocks, 51 is a demodulation circuit, 52 is a byte count register, 54 is a residual character discrimination circuit, 59 is a MOD14 check circuit, 60 is a CRC check circuit, and 62 is a block ID check circuit. Indicates.

Claims (1)

[Claims] 1. A data block, which is block data, is compressed and recorded on a magnetic tape medium (40),
Creating means for creating block data amount information by counting the data amount of each incoming data block in a magnetic tape device for decompressing a compressed data block reproduced from the magnetic tape medium (40) to obtain the original data block An adding means for compressing each of the data blocks and storing the compressed data in a buffer and adding block data amount information to each; and an amount of data of the data blocks to be stored in the buffer is cumulatively counted, and the cumulative count value is a predetermined value. Recording means for adding the block data amount information by the number of blocks exceeding the number and continuously recording the compressed data blocks read from the buffer on the magnetic tape medium (40); and the compression continuously reproduced from the magnetic tape medium. Data blocks are compressed based on the block data amount information added to each compressed data block. And a dividing means for dividing the lock, a magnetic tape unit, characterized in that to obtain the original data block and decompresses the compressed data blocks divided.