JP2533484B2 - Magnetic tape control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In a magnetic tape device using a serpentine recording system, a directory block in which information indicating a state in a user data writing area of each track is recorded between user data writing areas of a magnetic tape. The directory block is read, and the magnetic head is positioned based on the read information.

[Industrial applications]

The present invention relates to a controller for positioning a magnetic tape, and more particularly to a magnetic tape control system in a serpentine recording system.

[Prior art and problems to be solved by the invention]

When a plurality of tracks are provided on the magnetic tape, when the data on the tracks is accessed, the magnetic tape is run to access the first track in the forward direction and then the second For the tracks, the magnetic head moves one track in the direction orthogonal to the running direction of the magnetic tape to access in the reverse direction, and then the magnetic head is sequentially moved to access in the forward direction, the reverse direction, and the meandering direction. A known serpentine recording method is known.

However, such a serpentine recording method has a problem that a predetermined track cannot be quickly accessed because each track is sequentially and sequentially accessed in the forward and reverse directions.

[Means and Actions for Solving Problems]

The present invention solves the above-described problems and enables a magnetic head device of a serpentine recording system to quickly position a magnetic head at an arbitrary position on an arbitrary track.

Therefore, according to the present invention, in the magnetic tape control method in which a plurality of tracks are provided in the longitudinal direction, and a magnetic tape having a plurality of data writing blocks on each of the tracks is accessed by the serpentine method, A directory block is provided between data write blocks on at least one track of the magnetic tape, and the validity bit of each track of the corresponding data write block and the data write block of the track are provided in the directory block. Write the information that shows the data contents in the. Next, at the time of operation such as file search,
By reading the contents of the directory block, the information of the data write block of the corresponding track can be obtained, and the magnetic head is positioned based on this information.

As a result, in the present invention, it is possible to perform positioning quickly even when the corresponding track is accessed by the serpentine method.

〔Example〕

FIG. 1 is a block diagram showing the inside of a magnetic tape as an embodiment of the present invention.

In FIG. 1, the magnetic tape 1 is track 0 TRK 0
6 tracks from 5 to TRK 5 are provided in parallel with the running direction of the magnetic tape. Each track is also provided with a plurality of user data writing areas 11, 12, 13 along the traveling direction. Directory blocks 22 and 23 are provided between these areas, and the directory block 22 corresponds to the data writing area 11.

As shown in FIG. 2, the contents of the directory block 22 indicate the state of each track with a word of 2 bytes (16 bits) per track. That is, the bind address (B.ADD) 00 corresponds to track 0 TRK 0, and if the 15th bit is “1”, there is no data on track 0 TRK 0.
When it is "0", it indicates that there is data in track 0 TRK 0, and the number of file marks is stored in 14-0 bits.

In the serpentine recording method, normally each track is indicated by an arrow A ₁ →A ₂ →A ₃ →A ₄ →A ₅ →A ₆ →A ₇ →A ₈ →A ₉
→A ₁₀ →A ₁₁ Arrow A ₂ ,A ₄ ,A ₆ ,A ₈ ,A ₁₀
The magnetic head is moved by. The direction A ₃ ,A ₇ ,A ₁₁
Is reverse to the forward directions A ₁ , A ₅ , and A ₉ .

The control operation will be described below with reference to the circuit of FIG.

When a write-related (write-related) command to be accessed is transmitted from the beginning B of track 0 TRK 0, first, all the track defective bits of bit 15 of each byte of the directory block are cleared and the directory block is initialized. After that, writing is started in the user data writing area.

A magnetic tape controller (not shown) is provided with a counter 110, registers 111 and 112, and a directory block data writing circuit 113 shown in FIG. Counter 110
Has been cleared at the time of initializing. The counter 110 is also cleared by the track start signal S-TRK-S. On the other hand, the file mark detection signal S-FMD is applied to the counter 110, and counts the file mark detection signal detected in response to the data writing in the data writing area.

When the end E of track 0 TRK 0 is reached, counter 110
The number of file marks written in track 0 TRK 0 counted in step 1 is stored in the register 111.

Move the magnetic head to track 1 TRK 1 to move track 1 T
Move the magnetic tape to the starting end B of RK 1. At this time, the counter 110 track 1 TRK 1 track start signal S-TRK-
Cleared by S. When the magnetic tape runs along with data writing and reaches the end E of track 1 TRK 1, the contents of counter 10 are transferred to register 12, the magnetic head is moved to track 0 TRK 0, and the contents of directory block 22 are read. "0" indicating that there is data in the track 0 and track 1 of the directory data and the registers 111 and 11
The number of file marks stored in 2 is written to the corresponding byte address via the directory block data writing circuit 113. Then select track 2 TRK 2 and perform the same process as above. If a rewind command, an unload command, or a manual unload is executed after executing a write command in the middle of track n, EOD (End of Dat)
a) Write a block, erase the data to the end of that track, then read the directory block,
The directory block 22 is updated by setting "0" indicating that there is data in the (n+1)th and subsequent tracks to "1" indicating that there is no data.

The directory block is not accessed when only read commands are executed on the track being executed.

As described above, since the latest file information is recorded in the directory block for each track, when the multi-file space command is transmitted by the host device, for example, the computer, by reading the directory block, the target file is recorded It is possible to quickly and easily determine whether or not there is an error, and it is possible to reduce the execution time of an instruction from the host device.

In another embodiment of the present invention, a memory for storing directory data is provided in the magnetic tape control device, the directory data is read when the magnetic tape is loaded and stored in the memory, and at the end of processing of each track. Update memory contents. The contents of the directory block can be rewritten only when the magnetic tape is unloaded.

According to such a method, the number of times the directory block on the magnetic tape is accessed is reduced, so that the processing time can be further shortened. Further, even when a multi-space file command is received in the middle of each track, the magnetic head can be moved from the track position to the target track.

In the above embodiment, the directory block 22 can be placed on any track. Further, a directory block 22 shown in the figure can be used as the directory block for the user data writing area 11. That is, the directory block can be provided at any position between the respective user data writing areas.

〔The invention's effect〕

As described above, according to the present invention, even in the magnetic tape positioning control device of the serpentine recording system, it is not necessary to sequentially access each track by reading the contents of the directory block.
It is possible to shorten the time required for positioning on a specific track as compared with the conventional case.

[Brief description of drawings]

1 is a block diagram of a magnetic tape according to an embodiment of the present invention, FIG. 2 is a diagram showing the contents of the directory block in FIG. 1, and FIG. 3 is a circuit diagram for writing data in the directory block. ,. (Description of symbols) 1... Magnetic tape, 11 to 13... User data writing area, 22,23... Directory block, 110... Counter, 111, 112... Register, 113... Directory block data writing circuit.

Claims (1)

(57) [Claims] 1. A magnetic tape control system in which a plurality of tracks are provided in a longitudinal direction, and a magnetic tape having a plurality of data writing blocks on each of the tracks is accessed by a serpentine system. Directory blocks are provided between the data write blocks on at least one of the tracks, and the directory block includes the validity bit of each track of the corresponding data write block and the data write block of the track. A magnetic tape control system characterized in that information indicating data contents is recorded and the magnetic head is positioned based on the contents of the directory block.