JPH0869667A - Recording device - Google Patents

Abstract

PURPOSE: To erase data while maintaining a DAT format by recording dummy data having a prescribed length successively to new data and recording end discrimination data having a prescribed length successively to the dummy data. CONSTITUTION: Figure A shows the recording pattern of a magnetic tape 15 before data are erased, and by one backup of a data record, data 1 to 4 are recorded, EOD-IDs are recorded over 300 frames in the end section of the data 4 and after that the old data which were recorded before exist. In the tape 15 of Figure A, the data 1 and 2 are left as they are and the data 3 and succeeding data are erased, for example. In that case, when erasing unnecessary data, a first command is received from a host computer and several frames of amble sections are formed at the head of the data 3 as shown in Figure B. Then, EOD-IDs are recorded over 300 frames in the subarea. Moreover, when erasing all data, a second command is similarly received, EOD-IDs are recorded over 300 frames at the head of the data 3 as shown in Figure C, then amble sections are formed in all remaining sections.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus in a data recorder suitable for use, for example, when a rotary head type digital audio tape recorder (DAT) is used as a data recorder for recording and reproducing data sent from a computer or the like.

[0002]

2. Description of the Related Art In a computer, in order to protect (back up) data written on a hard disk or the like, such data is transferred to a data streamer (data recorder) once a day and recorded. Have been done.

As a conventional data recorder, an ordinary analog audio tape recorder has been widely used. However, in such an analog tape recorder, the consumption of the magnetic tape is extremely large, and since the data rate at the time of recording is low, it takes a very long time to transfer and record, and furthermore, the desired recording portion is searched for. There was a problem that it could not be performed easily.

Therefore, it has been considered to use a digital audio tape recorder, a so-called DAT, by a helical scan system using a rotary head which has been commercialized in recent years, as a data recorder. When DAT is used as a data recorder, data from a host computer is converted into a DAT format and recorded. In the DAT format, two inclined tracks formed when two heads having different azimuths make one rotation make one frame, and one frame makes one unit.
6-bit PCM audio data is interleaved and recorded, and auxiliary sub-data is also recorded. In that case, as described later, each track has P
A main area in which CM data is recorded and a sub area in which sub data is recorded are formed.

In the DAT, when another signal is newly recorded on the recorded tape, the previous signal is generally recorded by recording the new signal by so-called double writing without using the erasing head. I try to erase it.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the absence of an erasing head, when some or all of the past data once recorded becomes unnecessary, erasing must be performed in some way, and the DAT format must be maintained when erasing. It is necessary to erase while doing.

[0007]

According to the present invention, the first
In a recording apparatus that overwrites and records new data having a second recording length shorter than the first recording length on past data having a recording length of, the dummy data of a predetermined length is recorded following the new data. By recording the end identification data of a predetermined length subsequent to the dummy data, the past data of the unerased area is invalidated.

[0008] The unerased area of the past data is substantially erased without destroying a predetermined data format such as the DAT format.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a configuration in which DAT is used as a data recorder. 1 is DAT, 2 is an interface bus, 3 is a host computer, and 4 and 5 are inner buses. DAT1 is a recording / reproducing unit 6, a recording amplifier 7,
It includes a reproduction amplifier 8, a signal processing circuit 9, a RAM 10, a data controller 11, an interface board 12, a system controller 13, and a servo and motor drive circuit 14.

The system controller 13, the signal processing circuit 9, and the data controller 13 transmit predetermined signals such as an absolute frame number AFNO, check data, a mode instruction, a logical frame number LFNO, a determination result based on the check data, and a data transfer instruction. Has been given and received.

The recording / reproducing unit 6 is provided with a rotating head drum (not shown), and a magnetic tape is wound around a range of about 90 degrees around the drum and transferred by a capstan. This drum has A with different azimuth angles,
B2 heads are provided, and two tilted tracks are recorded and reproduced on the tape by one rotation of the drum.

From the host computer 3 to the buses 5, 2, 4
Digital data supplied via the interface board 12 is manually input to the system controller 1
3, the data controller 11, the RAM 10
By performing predetermined signal processing in the signal processing circuit 9 and the like, the above-described conversion to the DAT format is performed. The formatted signal is supplied to the recording / reproducing unit 6 through the recording amplifier 7 and the head A,
B is recorded on the magnetic tape.

The signal recorded on the magnetic tape is reproduced by the heads A and B, and the reproduced signal is supplied to the signal processing circuit 9 through the reproducing amplifier 8 where the digital data which is inversely converted and taken out is a data controller. It is supplied to the host computer 3 through 11, the interface board 12, and the buses 4, 2, and 5.

In the apparatus described above, the format of the DAT recorded on the magnetic tape is as shown in FIG.

In FIG. 2, the tape 15 has a head A,
By one rotation of B, two inclined tracks T _A ,
T _B is formed from below as indicated by the arrow a in the figure. One frame is composed of these two tracks T _A and T _B. One track T _A (or T _B ) is composed of 196 blocks, and one block is composed of 288 bits. Of these, 34 blocks at both ends are sub-areas, and 128 blocks in the center are main areas.

The sub-area is further divided into several sections. That is, from the lower end of the track to the margin,
Preamble part for PLL of subcode, first subcode part, postamble part, gap part of block part,
Tracking (ATF) signal portion, inter-block gap portion, data PLL preamble portion, inter-block gap portion, ATF signal portion, inter-block gap portion, sub-code PLL preamble portion, second sub-code portion , A postamble part and a margin part are provided.
Of these, the first and second sub-code parts are each composed of 8 blocks, and the other parts are each composed of a predetermined number of blocks. Note that the length scale in the figure is not accurate.

The main area is made up of 128 data blocks, and one of the blocks is, as shown in FIG. 3, from the beginning of the block, a synchronization signal, W such as PCM-ID, a part,
The block address and parity are arranged in 8 bits each,
Main data is arranged in the next 256-bit period. This main data is a 16-bit P channel for each of the L channel and the R channel when handling audio signals.
It is CM data. These 16-bit main data are interleaved in the main areas of the two tracks T _A and T _B (1 frame) and are arranged together with the parity.

In this case, approximately 5760 bytes of data are recorded in the main area of one frame. When used as a data recorder, the data sent from the host computer 3 is converted into 16-bit data and treated in the same manner as the PCM data, and these data are converted into those shown in FIG.
And is recorded in the main area of one frame.

That is, in FIG. 4, the above-mentioned 5760 bytes are converted into words (0 to 143) each having 4 bytes (32 bits).
9) The word is divided into 16-bit (2 bytes) L channel and R channel according to the audio signal. In this format, a synchronizing section is first provided in three words (12 bytes), the first 1 byte of the synchronizing section is all "0", the next 10 bytes are all "1", and the last 1 The bytes are all set to "0".

Next, an 8-word (32-byte) header section is provided. The 4 bits on the MSB side of the first half byte of the L channel of word 3 in this header part are used as the format ID indicating the format of the data decoder, and the last 4 bits are undecided. The remaining three bytes of this word 3 are logical frame numbers (LF
N0) area, and the LFNO consisting of 8 bits provides, for example, 23 frames as one unit, and binary values indicating the serial numbers 1 to 23 of the frames.

In the subsequent words 7-1438, a total of 57
A data portion of 28 bytes is provided, and a data signal from the host computer 3 is sequentially provided by 4 bytes for each word.

Further, a word 1439 is an error detection code (EDC) part. For each of the data signals of the above-mentioned header part and data part, an error detection code (EDC) for a data string in which each data bit is viewed in the vertical direction is provided. ) Is generated and provided.

Here, in the DAT format,
The data of the L channel and the data of the R channel are arranged so as to be alternately recorded in two tracks by 2 bytes and recorded, and for example, the azimuth (±) of the heads A and B forming the tracks on both sides of the figure. ) Is done as shown. Therefore, as described above, an EDC is generated for a data string in which each data bit is viewed in the vertical direction, and thereby EDs are generated for two tracks forming one frame.
C can be generated.

Therefore, according to this format, the BDC
It is possible to determine the remaining unerased area in the main area by performing the calculation. That is, if one track remains unerased in the above format, the EDC
Every other data to generate the ED
The calculation of C is not performed correctly. Therefore, by detecting this value, it is possible to determine the unerased portion.

Next, the logical frame number LFNO will be described with reference to FIG.

As described above, the LFNO has, for example, 23 sets of frames as one unit, and each frame is given a serial number from 1 to 23. That is, 1 every 23 frames
..,...,... In FIG. 5, the entire LFNO is composed of 8 bits, and the MSB of which is the last frame of the unit, that is, if the unit is 23 frames, it indicates the 23rd frame. Last frame ID (LASTF-ID).

An ECC frame ID indicating that the next 1 bit of the MSB is an ECC frame for error correction
(ECCF-ID), and the next 6 bits are L of 1 to 23.
Shall represent FNO. Therefore, LFNO is 164
Can be selected to any length other than 23 frames. In that case, it can be known from the LASTF-ID that the frame is the last frame of the unit. Also ECCF
-The ID may be multiple-written not only in one frame but also in a plurality of frames.

By using such a unit to which the LFNO is attached, a break at every predetermined amount of data becomes clear, and signal processing becomes easy. Further, by changing the maximum value of LFNO and selecting the unit length to be an appropriate size, signal processing can be performed more easily.

Next, the data structure of the first and second subcode parts in the subarea will be described.

The first and second sub-code parts are each 8
Sub-code blocks, each of which has 20 sub-code blocks.
48-bit data can be recorded.

FIG. 6 shows the structure of a sub-code block. After an 8-bit synchronization signal, W ₁ , W ₂ and parity are arranged, 256-bit sub-code data including parity is arranged. This subcode data is composed of four packs, and one pack is composed of 8 × 8 bits (8 symbols).

The contents of W ₁ and W ₂ are different between the block whose block address is EVEN and the block whose ODD is ODD, and the pack numbers (1 to 7) are changed to EVE as shown in FIG.
It is attached to the N block and the ODD block.
The eighth pack is provided with a C ₁ code for error detection.

W ₁ of the EVEN block is composed of a 4-bit area ID and data ID, and W ₂ is composed of upper 1 bit “1”, 3-bit pack ID, and 4-bit block address. Each W ₁ of the ODD block consists of an undecided part of 4 bits and a format ID, and W ₂ is a high-order 1 bit “1”, a 3-bit all-zero code,
It consists of a 4-bit block address. Also EV
When 4-bit area ID in W ₁ of the EN block is "0100", EOD-ID indicating an end of data
(End of data ID).

Each of the packs 1 to 7 is divided into 8 words of 8 bits, and each word includes, for example, a code indicating the lead-in area of the recording start portion on the tape and the lead-out area of the recording end portion. Various kinds of codes such as a code, a code indicating a recording date and time, an absolute frame number, a logical frame number, etc. are provided together with the parity.

FIG. 7 shows the structure of the pack 3 as an example of the seven packs.

This pack 3 is composed of eight words PC1 to PC8 each having 8 bits. The upper four bits of PC1 are provided with a pack number (here, "0011" indicating pack 3), and the lower four bits are provided with a format ID. PC2 is an undecided part. The upper four bits of the PC 3 are provided with an area ID indicating the lead-in area or the lead-out area. An absolute frame number (AFNO) is represented by a total of 20 bits including the lower 4 bits of PC3 and PC4 and PC5. This AFNO
Is a serial number assigned to all frames recorded on one tape. Next, check data CD according to the present invention is provided by a total of 16 bits of PC6 and PC7, and parity of PC8 is provided for PC1 to PC7.

The 16-bit check data CD is:
One track (T _A or T provided with this pack 3
_{This is} the exclusive OR of all data (data from the computer) existing in the main area provided in _B ). Alternatively, as the check data CD, an error detection signal such as CRC for all the data existing in the main area may be used.

This check data is also used for other pack PCs.
It is also possible to improve reliability by providing it in the undecided part of PC1 and PC2 to 7 so as to perform multiple writing. In this case, one track is provided with first and second subcode portions each having 8 blocks, and each block has 7 packs. Therefore, one track has the same check data CD.
Can be recorded up to 56 times.

Such check data CD is used as follows.

At the time of reproduction, the check data CD read from one track and the exclusive OR of the data read from the main area of the track are compared. As a result, if they do not match, it means that either the entire main area has been erased or the entire sub area has been erased (the check data CD of the previous image was also erased). Can be determined. Further, when the both match, it is possible to determine whether both the entire main area and the entire sub area are correct or both are incorrect. To find out whether the main area or sub area is correct or incorrect, use LF
Using NO and AFNO, it can be determined by the following method.

FIG. 8 shows the order of the judgment. Based on the judgments in the respective steps S1 to S4, the judgment criterion in FIG. 9 is obtained, and the contents of the judgment in FIG. 10 can be known based on this judgment criterion. .

In FIG. 8, first, it is checked in step S1 whether data in the main area (hereinafter referred to as main data) has been corrected by the C ₁ and C ₂ codes.
If the correction could not be made, it is determined as C in FIG. 10 that the main data of the track had a dropout, and a message to that effect is sent. When the correction is successful, the continuity of LFNO in the main area is checked in the next step S2. When there is no continuity, it is determined that there is a drop-in in that track, assuming that it is B in FIG. 10, and a message to that effect is sent.

When the LFNO has continuity, the check of the main area is finished, and then the sub area is checked in step S3. For pack data of the sub-area, C ₁ code correction, pack parity, to check the reproducibility of the pack data by multiple match or the like. If this check could not be performed, it is determined that (5) in FIG. 10 is satisfied, and it is determined that the data (sub-data) in the sub-area has a drop-in and the main data is correct. If the reproducibility check is successful, the AFNO
1 and the main data based on the check data CD, the judgment criteria of FIG. 9 are obtained based on the results of the respective checks, and the judgment criteria of FIG.
The content of the judgment of 0 is calculated.

The contents of each judgment are: A- (1) ... The main data is correct. A- (2)... There was a drop-in in both the main data and the sub data. A- (3) ... There was a drop-in in the main data. AFNO happened to be continuous. A- (4)... There was a drop-in in the sub data.
In this case, it is assumed that the AFNO is self-propelled and the main data is correct. A- (5) ......... There was a dropout in the sub data. In this case, it is assumed that the AFNO is self-propelled and the main data is correct.

When a drop-in is detected by the check data CD, a flag is set, and error correction using the error correction code ECC can be performed based on the flag. Furthermore, in order to prevent misreading of the check data CD and the data in the main area, the check data CD
You may make it detect several times.

Next, a data erasing method according to the present invention in the data recorder using the DAT format described above will be described with reference to FIG.

FIG. 11A shows a magnetic tape 15 before erasing data.
The data 1 to 4 are recorded by one backup of the data record, and the EOD-ID (see FIG.
There are old data (past data) recorded for 0 frames and then recorded before.

A case will be described in which, for example, data 3 and subsequent data are erased from the tape 15 shown in FIG. In this case, the contents of the erasure include (1) erasure indicating that all data below data 3 are unnecessary (hereinafter referred to as unnecessary erasure), and (2) data 3
There are two types of erasing all of the following data (hereinafter referred to as complete erasure). When requesting the unnecessary erasure, first
Command signal is sent from the host computer, and the second command signal is sent from the host computer when the above complete erasure is requested.

(1) In the case of performing unnecessary erasure Upon receiving the first command signal, first, as shown in FIG. 11B, one or two or several frames of an amble portion are formed at the beginning of data 3. The amble is formed by dummy data such as all zeros. Next, the BOD-ID is recorded in the sub area over 300 frames.

As described above, when the tape 15 shown in FIG. 9B is reproduced, the amble portion is first detected, and then the EOD-I
Since D is detected, it is understood that a part of the subsequent data 3 and all the data below it are unnecessary.

(2) In the case of complete erasure When the second command signal is received, first, as shown in FIG. 7C, the EOD-ID is recorded at the beginning of the data 3 for 300 frames, and then the amble part remains. It is formed in all sections. Similarly, the amble portion may be formed in several frames before the EOD-ID of the data 3.

According to the above, since the EOD-ID is detected and the amble portion is formed next when the tape 15 shown in FIG. 7C is reproduced, it is understood that all the data after that is erased.

The amble part is formed by setting the above-mentioned LFNO in the main area to all zeros, or setting the above-mentioned AFNO and check data CD in the sub-areas to all zeros, or both of them.

According to the data erasing method described above,
The contents of erasure at the time of erasure are distinguished by the first and second command signals, and the contents of erasure can be known by detecting a recording pattern during reproduction. Further, according to this erasing method, data can be substantially invalidated without using an erasing head without breaking the DAT format.

[0055]

According to the present invention, in the recording apparatus for overwriting and recording new data having the second recording length shorter than the first recording length on the past data having the first recording length, Since the dummy data of a predetermined length is recorded following the data, and the end identification data of a predetermined length is recorded subsequent to the dummy data, the past data in the unerased area is invalidated.
Data can be erased without using an erase head while maintaining a predetermined data format such as AT format. Further, there is obtained an advantage that the erasing time of the past data in the area which has not been erased is omitted.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a format of DAT.

FIG. 3 is a data configuration diagram of a main data block.

FIG. 4 is a data configuration diagram of a main area of one frame.

FIG. 5 is a data configuration diagram of a logical frame number.

FIG. 6 is a data configuration diagram of a subcode block.

FIG. 7 is a data configuration diagram of a pack of subcode blocks.

FIG. 8 is a flowchart illustrating an error determination method.

FIG. 9 is a diagram showing error determination criteria.

FIG. 10 is a diagram showing the contents of determination.

FIG. 11 is a recording pattern diagram of a magnetic tape showing a data erasing method according to the present invention.

[Explanation of symbols]

T _A, T _B Track 1 DAT 3 host computer 13 the system controller EOD-ID data end ID

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kentaro Odaka 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Masaki Yamada 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Katsuzumi Inazawa 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (1)

[Claims] 1. A recording apparatus which overwrites new data having a second recording length shorter than the first recording length on past data having a first recording length, and a predetermined length following the new data. The recording device, wherein the past data of the area which has not been erased is invalidated by recording the dummy data of 1. and the end identification data of a predetermined length following the dummy data.