JPH02278574A - Error track pointer control system - Google Patents

Abstract

PURPOSE:To improve performance for reading data by processing the reset control of an error track pointer by a microprogram in a process to execute again the reading of data to the same data block. CONSTITUTION:In a magnetic tape unit 10 for which an adaptive cross parity code system is adopted, the data red from a magnetic tape 19 are temporarily stored to a discuing buffer 14 of a magnetic tape controller 11. The data, for which skew is corrected, are sent to an ECC processing part 15 and ECC processing is executed to the data. Then, output information are sent to a microprogram control part 12. In a read data discrimination part 17, the data are inputted from the buffer 14 and discriminated. When a resynchronizing signal is detected, information are sent to an error track holding circuit 13 and when a data error is detected, a signal to set an error track is sent to the holding circuit 13. In a control part 12, on the basis of the information from the processing part 15, the reset of the error track pointer is controlled in the retry process of the data read.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figures 4 and 5) Problems to be solved by the invention Means for solving the problem (Figure 1) Action (Figure 1) Figure 1) Embodiment (Figures 2 and 3) Effects of the invention [Summary] Error Regarding the trunk pointer control method, when reading data in a magnetic tape device that adopts the AXP code method, error 1 - rack pointer reset control. The purpose is to improve the data reading performance by properly performing the error control, which controls the reset of the error track pointer when reading a data block in a magnetic tape device that adopts the AXTI (adapted cross parity) code system. In the track pointer control system, the magnetic tape control device includes a desqueuing Hanofa, an ECC processing section, a read control section, a read data discrimination section, an error track holding circuit, and a cogram system '4ff1 in a microbe.
If there is an error in the read data, in the process of re-reading data from the same pig block, the error track pointer held in the error track holding circuit is updated in 141 synchronization frames. The control unit is configured to determine whether to reset or not by processing a microprogram of a microprogram control unit.

[Industrial application field]

The present invention relates to an error track pointer control method, and more specifically, it is used in a magnetic tape device that employs an AXP code (adaptive cross parity code) method. Error 1- which improves data reading performance by making it possible to arbitrarily change whether or not to move the error track pointer when reading a data block.
This invention relates to a rack pointer control method.

[Conventional technology]

Conventionally, when recording and reproducing data on a magnetic tape device, various error correction methods have been used for data, namely E
CC (Error Checking and Co.
rrecLion) was adopted.

General ECC methods include a method that uses ECC characters that depend only on one data frame.When reading data recorded using such an ECC method that depends only on one data frame, resynchronization frames (Re-5
ynchro Fra+me) had no effect on the data frames before and after it.

Therefore, the EC that depends on only one data frame
In the case of C method, the error track pointer is also restartedjj
It was possible to reset 1- in j frame.

However, recently, G CRE CC (Group Cod
A, which is a type of edRecordin (HI?, CC)
XP (＾adaptve Cross Parity)
A method using a code (adapted cross-validity code) has been developed. This will be explained below.

Figure 4 shows the data format on the magnetic tape.
It is a figure showing an example.

In the figure, 5YNC indicates a synchronization signal, and R(!-5YNC indicates a resynchronization signal.

This resynchronization signal is a code that is added every 1/1 (72 frames), and is a special code (042]-10
0010001) is used.

In this example, 18 trunks are used as the number of tracks.

Figure 5 is an explanatory diagram of the AXP code (AχP on the magnetic tape).
code).

As shown in the diagram, this magnetic tape has top and bottom A,
It is divided into B, each consisting of 9 tracks, making a total of 18 tracks and 7 tracks.

I is the VRC bit (Vertical
Redundancy check bit: Vertical redundancy check pin 1-), 2 does not indicate the V RC bit of the B side track.

Also, 3 is 1) 17C focus (I]i of Δ side 1-rack
++I Honal Redundancy check
Focus; Opposite line direction redundancy check bit), 4 is the B side tracker.
Tsuku's DRC binoto is not shown.

DRC bit 3.4 is a redundancy check bit in the diagonal direction over three frames, and DRC bit 3 and D
RC bit 4 is a test pin 1- on lines that intersect with each other.

Such test bins 1 to 1 are added to two upper and lower tracks on the magnetic tape at different locations.

A feature of the 18-track magnetic tape device employing the AXP code system as described above is that in order to perform ECC, three frames of data are required from the current ECC bits.

Moreover, a special code called a resynchronization frame (Re-3YNC) is added every fixed period (72 frames).

Therefore, when reading data on a magnetic tape, even if a resynchronization frame is read, the nG of this frame is
To perform ECC on the I data frame, data for two frames from the resynchronization frame is required.

Therefore, it is not possible to read the synchronization frame and immediately set the error track pointer.

In addition, if the length of 1 bit is long (for example, 2
0 Pitsu H has relatively high reliability, but AXP written in
In the case of the code system, the resynchronization focus length is short (9 focuses).

In such a case, even if the resynchronization frame is correctly detected, there is a very high possibility that the subsequent data frame 1 will have an error.

Therefore, in those that adopted the AXP code method, the conventional method of resetting using a resynchronization frame could not be used as is.

[Problem to be solved by the invention]

The above-mentioned conventional devices had the following drawbacks.

That is, when reading data in a magnetic tape device employing the AxP code system, it is not possible to detect the 11t synchronization frame and immediately reset the error trunk pointer.

The present invention solves these conventional drawbacks and improves the reading performance of a magnetic tape device by appropriately controlling the reset of the error track pointer when reading data in a magnetic tape device that employs the AXP code method. purpose.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention, and the present invention will be explained in detail below based on this diagram.

In the figure, 10 indicates a magnetic tape unit (MTU), 1
1 indicates a magnetic tape controller (MTC).

12 is a microprogram control unit, 13 is an error track holding circuit, 4 is a deskewing buffer, and 15 is an E
A CC processing section, 16 a read control section, 17 a read data discrimination section, 8 a reading hand, and 19 a magnetic tape.

The deskewing buffer 14 temporarily stores data read from the magnetic tape 19 and corrects the skew of the pig.

In the FCC processing unit 15, the deskewing Hanwha 14
It inputs data from , performs RCC processing, and sends output information (whether the data was read or not, information on the cap) to the microprogram control section 12 .

The read data discrimination section I7 inputs and discriminates the data from the deskewing buffer 14, and when a resynchronization signal is detected, it sends information to the error track holding circuit 13, and when a data error is detected, it disables the error track. A signal to be set is sent to the error trunk holding circuit 13.

In the microprogram control unit 12, based on the information from the r;, cc processing unit 15, the data read number 1-
In the process of writing, it is determined whether or not to reset the error track pointer in a resynchronization frame, and a signal is sent to the error track holding circuit 13.

[Effect] Since it is configured as described in Section 1, it has the following effects.

When reading a data block on a magnetic tape recorded in accordance with the AXP code, if the data block is written in a poor condition, it will not be possible to read the data correctly.

In such a case, the magnetic tape is returned and the same data block is read again (retry).

In the process of this retry, the microprogram control unit 11 determines whether to reset the error track pointer in the resynchronization frame (Re-SYNC frame) or to hold it in the resynchronization frame, Error 1 - Issue an instruction to the rack holding circuit 13.

That is, by processing the error track pointer reset condition using the microprogram within the microprogram control section 12, data reading performance is improved.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a block 1 of one embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same parts.

In the figure, ]0 is a magnetic tape unit (MTU), 1
1 indicates a magnetic tape controller (MTC).

12 is a microprogram control section, I3 is an error trunk holding circuit, 14 is a deskewing buffer, 15 is an ECC processing section, 16 is a read control wholesale section, 17 is a read data discrimination section, 18 is a read bend, and 19 is a magnetic 20 is a demodulator, 21 is an amplifier, and 22 is a preamplifier.

The deskewing buffer I4 temporarily stores read data to correct data skew, and also sends a resynchronization frame (Re-3Y) to the error l/rack holding circuit 13.
Send NC(i)7[/-, A).

If the magnetic tape has 18 tracks, this resynchronization frame outputs signals for 18 tracks corresponding to each track.

The error track holding circuit 13 includes an AND gate 18 and
JK flip-flop 19, A
The JK-Flimb flop 19 is reset by the output of the ND gate 18.

Further, the number of error holding circuits 13 is the same as the number of tracks (in the case of I8 tracks, 18 All corresponding to each track) are provided.

The read data determination unit 17 manually determines the data from the deskewing buffer 14 and determines the detected resynchronization frame (Detect Re-SYNC).
A manual input is made to the AND gate 18 of the error track holding circuit 13.

Further, a signal for setting an error track is manually set in the JK flip-flop 19 of the error track holding circuit 13 (Set Error Track (i) is sent).

This signal is also equal to the number of tracks (1B for I8 tracks)
) is output and sent to each JK flip flop I9.

In the ECC processing unit 15, the deskewing buffer 14
The microprogram control unit 12 manually inputs the data and performs ECC processing, as well as information regarding data errors, such as information such as whether the pig was readable or unreadable.
send to

In the microprogram control unit 12, the above-mentioned EC
Based on the information from the C processing unit 15, processing is performed by a microprogram and a signal is output to the AND gate 18 of the error l/rack holding circuit 13.

In this process, a process is performed to determine whether or not to reset the error track pointer in the resynchronization frame, and the error track holding circuit 13 is controlled.

FIG. 3 is a diagram showing an operation flowchart of the above embodiment.

First, when there is an instruction to read a data block (a), a signal from the microprogram control unit 12 causes the error track holding circuit 13 to read the error track pointer ETP (i).
) Instruct the glue cent.

Next, read the data block from the magnetic tape '2 (
c) The read data discriminator 17 determines whether there is an error in the data check, such as an uncollectible error or a CRC error (2).

If there is no error, the process ends normally (E); if there is an error, read the data from the same block again or try again, and increment the counter by 1 (E).

Then, it is determined whether the retry has been executed a predetermined number of times (g), and if the retry has been retried a predetermined number of times, an error is reported as an abnormal termination (l).

However, if the predetermined number of attempts have not been made, it will not be possible to determine whether the ETP reset instruction has been given the predetermined number of times.)
, if the ETP reset instruction is given a predetermined number of times,
The microprogram control unit 12 instructs the AND gate 18 to hold the Snake TP (N).

Thereafter, it advances to the error block and reads the data block for the same block again.

As mentioned above, the data check of the magnetic tape is read, and if there is an error, a retry is performed, but at that time,
The error I/rack pointer reset condition is processed by the microprogram control unit (2).

That is, data reading performance is improved by processing in a microprogram whether to reset the error track pointer FTP at the resynchronization frame or to hold it even at the 11th synchronization frame.

[Effects of the Invention] As explained above, the present invention has the following effects.

(1) When reading a data block recorded by the AXP code, if the data is written in a poor condition, an error 1 to 7 pointer with an error will be generated.
It can be read by arbitrarily changing whether to reset it in the resynchronization frame or to hold it even in the resynchronization frame.

(2) If data can be read in the process of multiple attempts, data reading performance improves.

17--Read data discrimination section 18-read head 19-Magnetic tape

[Brief explanation of drawings]

Fig. 1 is a principle diagram of an error track pointer control method according to the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a diagram showing a flowchart of the above embodiment, Fig. 4 is one of the data processing formats on the magnetic tape.
A diagram showing an example, FIG. 5 is an explanatory diagram of the AXP code. 10-Magnetic tape unit (MTU) 11-Magnetic tape controller (MTC) 12-Micro program control section I3-Error track holding circuit 14-Deskewing buffer 15-ECC processing section I6 Read control section

Claims (1)

[Scope of Claim] A magnetic tape control device (11) in an error track pointer control method for controlling the reset of an error track pointer when reading a data block in a magnetic tape device adopting an AXP (adaptive cross parity) code method. Inside, there is a deskewing buffer (14) that temporarily holds read data, and an ECC processing unit (14) that processes errors in the read data.
5), a read control section (16) that controls data reading, and a read data discrimination section (16) that discriminates read data.
7), an error track holding circuit (13) that holds an error track pointer, and a microprogram control unit (12) that processes reset control conditions for the error track holding circuit (13), If an error occurs, in the process of re-reading data from the same data block, the error track pointer held in the error track holding circuit (13) is determined whether or not to be reset in the resynchronization frame. An error track pointer control method characterized in that control is performed by processing a microprogram in the microprogram control section (12).