JPH01319104A - Magnetic tape control device - Google Patents

Abstract

PURPOSE:To decrease the loss of a medium by providing a counter to count up or count down a pulse from a generator, which is connected to a capstan, when writing and rewinding is executed to a magnetic tape and checking a counted value when the tape is rewound. CONSTITUTION:When data are written to the magnetic tape, instruction is executed from a microprocessor 4 so that a counter 12 can count up a strobe from a VF circuit 15 after the tape is reset by a reset circuit 13. When the data are finished to be written in one block, it is checked whether there is any error or not in the data to be just written. Here, when there is no error, the writing of the next block is executed. However, when the error is detected here, the magnetic tape is caused to proceed in a reverse direction and back read is executed. Then, the tape is positioned to a preceding gap. At such a time, instruction is executed from the microprocessor 14 so that the counter 12 can execute the count down with the strobe from the VFO circuit 15. Thus, it can be confirmed that the magnetic tape is positioned to a normal position. Then, the loss of the medium can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to magnetic tape control devices, and more particularly to tape control in the case of media failure.

Conventional technology When recording data on a magnetic tape medium, the data is 6
The data is divided into multiple blocks and recorded on the tape.

The space between these blocks is called a gap, and 6
J& It has been erased and nothing is written on it.

When the magnetic tape control device writes or reads data, the tape is positioned using this gap as a mark.

Especially if there are scratches etc. on the magnetic tape, error 11! will be displayed when checking ``Ad after Vrito'' after writing data. At this time, the magnetic tape controller is used.

The magnetic tape is rewound to the gap before iM of the block in which data has been written and positioned at the immediately previous gap. Furthermore, the data on the magnetic tape is erased from this position by the amount of the leak block, and the data that could not be written due to an error is subsequently written. As a result, the data is erased from the scratched part on the magnetic tape, and the data is Since no writing is performed, writing can be performed normally.

On the other hand, since magnetic tape is made of a thin film, folding of the magnetic tape often occurs when a loosely wound tape is mounted in a magnetic tape device and started up, such as during transport.

These folds are different from scratches on the magnetic tape, and when such a magnetic tape is read, this part does not come into close contact with the magnetic head, so when viewed from the output of the magnetic head, the output of this part disappears and it becomes a gap. Looks similar.

In addition, similar to scratches on magnetic tape, errors occur after data is written, so the magnetic tape controller performs the same processing as when dealing with scratches on the magnetic tape. The tape is rewound until the end and positioned at the gap. However, in this case, the folded part of the tape appears to be an erased part with no output, just like the gap, so the positioning is done at one wrong position. .

Conventionally, in such cases, the magnetic tape medium itself became unusable.

Problems to be Solved by the Invention In the conventional magnetic tape control device described above, when the magnetic tape is bent, it is impossible to distinguish it from the gap part where data has been erased by looking at the output from the magnetic head. Therefore, if there is a poem like this, it becomes impossible to position the tape.

The medium itself becomes unusable.

Furthermore, if the tape is mistakenly recognized as a gap and positioned at a tape fold, the error data is written after erasing the gap from this position. For this reason, the part before the tape bend remains and an extra block is created. This is not known immediately after writing, so it becomes data addition, and is a serious problem in usage where verification is not performed after writing. It becomes an obstacle.

The present invention has been made in view of the above-mentioned conventional circumstances,
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a novel magnetic tape control device which makes it possible to eliminate the above-mentioned drawbacks inherent in the prior art.

Means for Solving the Problems In order to achieve the object described above, a magnetic tape control device of the present invention includes a counter that counts strobe pulses for writing data to and reading data from a magnetic tape device, and a magnetic tape control device for writing data to a magnetic tape device. A set circuit that resets this counter each time an instruction is given to the tape device, a microprocessor that controls data transfer between the magnetic tape device and the central processing unit, tape positioning, etc. The device includes a switching circuit for switching the counting direction of the counter to addition or subtraction, and a read buffer for reading the value of the counter from the microprocessor.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

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

Referring to FIG. 1, the VFOH path 5 generates a write strobe and a read strobe from data input to and output from the magnetic tape device 11.

Write strobe and read strobe are counter 12
are entered and counted. The counter 12 is reset to zero by a reset signal from the reset circuit 13, and counts up from the beginning of the block by an addition instruction from the microprocessor 14.

Furthermore, a countdown is performed upon error recovery based on a subtraction instruction from the microprocessor 4.

FIG. 2 shows how blocks are recorded on a tape medium, and each block is divided by a gap and recorded. Furthermore, the above-mentioned folds occur in the block as shown in the figure.

Next, the operation of this embodiment will be explained using this diagram.

Usually when writing data to magnetic tape.

After being reset by the reset circuit 13, the viro circuit 15
The microprocessor 4 instructs the counter 12 to count up the strobes from the microprocessor 4.

When one block of data has been written, a check is made to see if there are any errors in the written data. This can be done by reading the written data from a read head, which is usually placed after the write head.

If there is no error here, the next block is written, but if an error is detected here, the magnetic tape is advanced in the opposite direction and a pack read is performed to position it at the previous gap. Counter 1z is VFO circuit 1
The microprocessor 14 instructs the microprocessor 14 to perform a countdown using the strobe 5. When the positioning is performed normally and the positioning is performed at the immediately preceding gap, this counter 12 becomes zero, indicating that the positioning is performed normally.

However, as shown in Figure 2, if there is a mark □ on the magnetic tape and it is misrecognized and positioned at the bend when backreading, this counter l
``l'' is a value other than zero, indicating that the positioning is not performed normally. In this case, perform a grasshopper read again and check the counter value. When this value becomes zero, Now that it is located at the normal position, erase one block of data from this position.

The data with the error can be written again.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a counter is provided to count up or count down pulses from a generator connected to a capstan when writing and rewinding a magnetic tape, and when rewinding a magnetic tape, By checking this value, it can be confirmed that the magnetic tape is positioned at the correct position. As a result, even magnetic tapes with folds can be used normally, resulting in the effect of reducing media loss.

In addition, since rewriting is completely eliminated while the data is positioned at the wrong position, the writing operation no longer ends with one wrong data being written, which greatly improves the reliability of writing. I can do it.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figure 1 is a part of a block diagram showing an embodiment of the present invention, and Figure 2 is a diagram showing how data blocks are written on a magnetic tape. This shows a case in which a positioning error occurs during recovery in the case of tape bending. 11. Magnetic tape device 12. ,,counter,1
3. ,. Reset circuit, 14. ,,Microprocessor circuit. 15,,,VFOi road

Claims (1)

[Claims] In a magnetic tape control device that transfers data between the magnetic tape device and the central processing unit and controls the magnetic tape device, counts data write and data read strobes to the magnetic tape device. a reset circuit that resets the counter each time the magnetic tape device is instructed to write data; a microprocessor that controls the magnetic tape device; Alternatively, a magnetic tape control device comprising a switching circuit for switching to subtractive counting, and a read buffer for reading the value of the counter from the microprocessor.