JPH0223556A - Magnetic tape controller - Google Patents

Abstract

PURPOSE:To reduce overheads of commands by positioning tape marks for plural files skipped by one command. CONSTITUTION:The command for specifying the number of tape marks to be skipped, which is issued by a host CPU 11, is decoded by a command decoder 15 via a channel 12 and an interface control part 14, and a space counter 16 is informed of the completion of decoding via a signal line 20, a MPU 17 and a signal line 21. The number of tape marks to be skipped is stored via buss 22 into the counter 16. The command decoder 15 is informed of the receipt of data by the counter 16, which is then operated to subtract what the MPU 17 instructs for subtraction from the number of tape marks until zero. A tape mark detecting is instructed to a read/write control part 18 according to the decoding notification from the decoder 15 by the MPU 17, which also instructs the counter 16 about the subtraction and then instructs a TM detector 19 to stop its detection when the count value becomes zero.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a magnetic tape @ device having a detection mechanism for detecting tape marks on a magnetic tape. The purpose of this invention is to provide a magnetic tape system that reduces overhead, and includes a decoding means for decoding a command specifying the number of tape marks to be skipped, and a decoding means for decoding a command specifying the number of tape marks to be skipped specified by the command. a counting means for detecting a tape mark on a magnetic tape; a tape mark detecting means for detecting a tape mark on a magnetic tape; and each time an output of the detecting means is received, the counting means is subtracted, and when it becomes zero, the detection of the tape mark detecting means is stopped. and a control means for controlling the operation.

[Industrial Field of Application] The present invention relates to a magnetic tape control device having a detection mechanism for detecting tape marks on a magnetic tape.

Magnetic tape devices are known as the most popular external storage devices in today's computer systems.

This magnetic tape device records data by coating a magnetic material on the surface of a long strip of film with a length of 500 to 240 feet and a width of 1/2 inch, and magnetizing it in the longitudinal direction with a magnetic head. Ru.

The unit of data recording on a magnetic tape is called a block, and a plurality of blocks are collected to form one file.

With magnetic tape media having a storage capacity of 170 to 280 Mbytes per roll, a plurality of files are often recorded on one medium (reel). This is called a multi-file volume.

In this multi-file volume, files are identified by a special recording pattern called a tape mark (see FIG. 3).

Therefore, when processing files on a magnetic tape, it is necessary to efficiently retrieve a desired file.

[Conventional Extraction Technique] As a conventional magnetic tape control device, there is one shown in FIG. 4, for example.

In FIG. 4, 1 is the host CPU, 2 is the channel, and 3 is the host CPU.
is a magnetic tape controller. The magnetic tape control device 3 includes a channel interface control section 4, a microprocessor 5, and a read/write 1 control section 6.

A command from the host CPU 1 is given to the microprocessor 5 via the channel 2 and the channel interface control unit 3, and the microprocessor 5 operates the read/write 1-control unit 6 based on this command to read and write data on the magnetic tape 7. .

In this case, when a system job processes a file on the magnetic tape 7, a command (F
The head was positioned at a predetermined file position by using OR RD 5 PACE FILE Co AND).

[Problems to be Solved by the Invention] However, in such a conventional magnetic tape control device, when processing a file on a magnetic tape, for example, in FIG. When trying to read from or write to, I rarely had to issue the command three times. For this reason, the host CPU has to operate three times, which increases the number of steps and causes the problem that the file cannot be processed efficiently.

The present invention was made in response to these conventional problems, and is a magnetic recording medium that reduces command overhead by reading multiple files and positioning them to tape marks with a single command. The purpose is to provide a tape control device.

[Means to solve problems] FIG. 1 is a basic configuration diagram of the present invention.

In FIG. 1, 15 is a decoding means for decoding a command specifying the number of tape marks to be skipped, 16 is a counting means for counting the number of tape marks to be skipped specified by the command, and 19 is a tape mark on a magnetic tape 27. A tape mark detecting means 17 for detecting is a control means that reduces the count of the counting means 16 each time it receives the output of the detecting means 19, and stops the detection of the tape mark detecting means 19 when the count reaches zero.

[Operation 1] In the present invention, when the number of tape marks to be skipped is specified, the command is decoded, and on the other hand, the number of tape marks to be skipped specified by the command is stored in the counting means.

Each time the detecting means detects a tape mark on the magnetic tape, the counting means is subtracted, and when the count value reaches zero, the detecting means stops detecting the data mark.

Therefore, it is possible to skip a plurality of files with one command and easily position them at a predetermined tape mark.

Therefore, there is no need to issue commands multiple times as in the past, and there is no need for the host CPtJ to operate multiple times.

As a result, the number of steps can be reduced, command overhead can be reduced, and file processing can be performed efficiently.

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

FIG. 2 is a block diagram showing one embodiment of the present invention.

First, the configuration will be explained. In FIG. 2, 11 is a host CPU, 12 is a channel, and 13 is a magnetic tape control device. The magnetic tape controller @13 has a channel interface controller 14, a command decoder 15, a space counter 16, a microprocessor 17, a read/write controller 18, and a tape mark detector 19.

A command (HULTIFILE FO) that specifies the number of tape marks to be skipped is issued by the host CPU
RWARD 5PACE FILE Co +)
Channel 12i! -3 and the channel interface control section 14, and is decoded by the command decoder (decoding means) 15.

When the command decoder 15 decodes the command, it sends the command to the microprocessor 17 and the signal line 21 via the signal line 20.
The completion of decoding is notified to the space counter 16 via the space counter 16.

The number of tape marks to be skipped, which is a command parameter, is stored in a space counter 16 as a counting means via a bus 22. and space counter 16
notifies the command decoder 15 of the reception of the data via the signal line 23, and on the other hand, subtracts the number of tape marks until the number of tape marks becomes zero in response to a subtraction instruction inputted from the microprocessor 17 via the signal line 21.

The microprocessor 17 serving as a control means instructs the read/write control unit 18 to detect a tape mark based on the decoding notification from the command decoder 15, and also instructs the read/write control unit 18 to detect tape marks via the signal line 24. The status is notified to the channel interface control unit 14. Furthermore, every time the microprocessor 17 receives a tape mark detection signal from the tape mark detector 19 via the signal line 24, the microprocessor 17 causes the space counter 16 to output the signal line 2
1 to instruct subtraction, and when the count value of the space counter 16 reaches zero, the tape mark detector 19 is instructed to stop tape mark detection via the signal line 26.

One tape mark detector serving as a detection means detects tape marks on the magnetic tape 27 and sends a tape mark detection signal to the microprocessor 17 each time it is detected.

As shown in FIG. 3, the magnetic tape 27 has a plurality of files consisting of a plurality of blocks, and tape marks are placed between the files.

Next, the operation will be explained.

A command specifying the number of tape marks to be skipped from the host CPU 11 is decoded by the command decoder 15 via the channel 1273 and the interface control unit 14.

Subsequently, the number of tape marks to be skipped specified by the command is stored in the space counter 16 via the bus 22.

When the microprocessor 17 receives the command decoding notification from the command decoder 15, the microprocessor 17 activates the read/write control unit 1.
8 to perform tape mark detection.

The tape mark detector 19 notifies the microprocessor 17 of a tape mark detection signal every time it detects a tape mark on the magnetic tape 27 according to a detection instruction from the read/write control unit 18 .

The microprocessor 17 decrements the space counter 16 each time it receives a tape mark detection signal from the tape mark detector 19. When the count of the space counter 16 reaches zero, one microprocessor instructs one tape mark detector to stop detecting tape marks, and notifies the channel interface controller 14 of the end of the operation.

In this manner, in this embodiment, a plurality of files can be easily read and positioned on tape marks using one command.

Therefore, there is no need to issue commands multiple times, and there is no need for the host CPLJ 11 to operate multiple times, as in the prior art. As a result, the number of steps can be reduced, command overhead can be reduced, and file processing can be performed efficiently.

[Effects of the Invention] As described above, according to the present invention, it is possible to skip reading a plurality of files and easily position them to a predetermined tape mark with one command.

As a result, command overhead can be reduced and file processing can be performed efficiently.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a block diagram showing an embodiment of the invention, FIG. 3 is a configuration diagram of a magnetic tape, and FIG. 4 is a block diagram showing a conventional example. In the figure, 11... host CPU. 2... Channel, 13... Magnetic tape control device, 14... Channel interface control unit, 15...
Command decoder (decoding means), 16... Space counter (counting means), 17... Microprocessor (
control means), 18... read/write control unit, 19... tape mark detector (tape mark detection means) 20.21.23-26... signal line, 22... bus, 27... Magnetic tape. Fig. 1 of the basic flow, Fig. 8

Claims (1)

[Claims] Decoding means (15) for decoding a command specifying the number of tape marks to be skipped; and counting means (16) for counting the number of tape marks to be skipped specified by the command.
and tape mark detection means (19) for detecting tape marks on the magnetic tape (27), and each time an output of the detection means (19) is received, the counting means (16) is subtracted;
A magnetic tape control device comprising: control means (17) for stopping detection by the tape mark detection means (19) when the mark becomes zero.