JPH06124501A - Magnetic tape reading method - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding the reading method of a reciprocal recording type magnetic tape device, even if a medium defect in which a wrap mark cannot be detected correctly occurs, the tape is correctly folded and data reading can be continued. To aim. In a reciprocal recording type magnetic tape device in which a tape running direction is turned back by detecting lap marks WRAP1 and WRAP2 recorded at a turning point near the end of the tape, a forward side wrap mark W
When RAP1 is not detected, the tape is run to the physical tape end position FEOT of the magnetic tape, the tape is folded back, and the reading of the recording data on the backward side is continued on condition that the wrap mark WRAP2 on the backward side is detected. At the same time, if the forward wrap mark is normal and the backward lap mark is not detected, it is configured to continue reading the recorded data on the backward side from the time when the wrap mark on the forward side is folded back. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal loopback processing method for reading data in a reciprocal recording type magnetic tape device.

[0002]

2. Description of the Related Art In recent years, a magnetic tape apparatus has been used in which a 36-track magnetic tape is divided into 18 tracks in the forward direction and 18 tracks in the reverse direction for reciprocal recording.
In such a reciprocal recording type magnetic tape device, as shown in the recording format in FIG. 4, the magnetic tape device is located at a folding point near the end of the tape and is folded at two points on the forward side and the backward side. Lap mark WRAP1, which is a marker
WRAP2 is recorded, and when reading data, the lap mark is used to turn the tape running direction back.

[0003]

However, the conventional magnetic tape device has a problem that when a medium defect in which the lap mark cannot be detected correctly occurs, the tape cannot be folded correctly and an error occurs in the device. .

The present invention has been made in order to solve the above problems, and an object of the present invention is to correctly fold a tape and continue reading data even when a medium defect in which a lap mark cannot be detected correctly occurs. Is to provide a method that can be done.

[0005]

In order to achieve the above object, the magnetic tape reading method of the present invention detects the lap mark recorded at the turning point near the end of the tape so as to turn the running direction of the tape. In the reciprocating recording type magnetic tape device, when the forward wrap mark is not detected, the tape is run back to the physical tape end position of the magnetic tape, the tape is folded back, and the backward wrap mark is detected. If the wrap mark on the forward side is normal and the lap mark on the reverse side is not detected while continuing to read the recorded data on the reverse side under the condition of, the wrap mark on the forward side is returned. The reading of recording data on the reverse side is continued.

[0006]

[Operation] As shown in Fig. 4, the lap mark is located at the turnaround point of the magnetic tape and is located at the forward side and the reverse side.
It is recorded in some places. Therefore, the case where the lap mark becomes abnormal is either one of the lap marks or both of them.

If neither lap mark is present, the normal operation of the system is not guaranteed from the beginning, and in this case, it is treated as an apparatus error as in the conventional case. In the magnetic tape reading method of the present invention, the lap mark is not detected. In the case where there is only one, the tape is correctly folded and data reading is continued.

When there is only one lap mark, there is no WRAP1 on the forward side and W on the reverse side.
There are two possible cases without RAP2. On the other hand, FIG.
As shown in FIG. 3, a physical tape end marker FEOT such as a light reflecting piece is provided at the end of the magnetic tape.
Therefore, the present invention uses the physical tape end marker FE.
If there is no wrap mark WRAP1 on the forward side using the OT, as shown in FIG. 1 (A), the tape is folded back by traveling to the physical tape end marker FEOT position, and the wrap mark WRAP2 on the reverse side is provided. On the condition that is detected, the reading of the data on the backward direction is continued.

The lap mark WRAP2 on the opposite side
If there is not, as shown in FIG. 1 (B), the reading of the data on the backward direction is continued from the time when the wrap mark WRAP1 on the forward direction is turned back. By doing this, even if one of the lap marks is missing,
It is possible to correctly fold the tape and continue reading data without causing a device error as in the past.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of a magnetic tape device configured by applying the method of the present invention. In the figure, 1 is a magnetic tape, 2 is a reciprocal recording type magnetic tape device, and 3 is a magnetic tape control device. The magnetic tape device 2 includes a magnetic head 21, a magnetic head drive unit 22, a write amplifier circuit 23, a read amplifier circuit 24, and a controller 25. The magnetic tape control device 3 is composed of a writing circuit 31, a reading analog circuit 32, a reading circuit 33, a block / mark recognition circuit 34, and a controller 35.

Next, the operation of the above embodiment will be described with reference to the flow chart of FIG. It is assumed that desired data is recorded on the magnetic tape 1 according to the recording format shown in FIG.

Now, when a data read command is given from the host device, the controller 35 of the magnetic tape controller 3 sends the data read command to the controller 25 of the magnetic tape device 2. The controller 25 of the magnetic tape device 2 controls the magnetic head 21, the tape drive unit 22, and the reading amplifier circuit 24 according to the read command,
The tape starts to move in the forward direction and the reading of the data recorded on the tape is started.

The recording data read by the magnetic head 21 is sent to the reading circuit 33 and the block mark recognition circuit 34 via the reading amplifier circuit 25 and the reading analog circuit 32.

The block / mark recognition circuit 34 identifies which data portion in the recording format shown in FIG. 4 is the currently read data, and sends the identification result to the controller 35. The controller 35 performs corresponding control according to the identification result.

When the reading of the data block DB from the magnetic tape 1 is started (step S1 in FIG. 3), the block mark recognition circuit 34 sends a data block start signal DBOB to the controller 35. Thereafter, while the data block DB continues, the data block processing (step S2) is continued, and the read block data is transferred to the higher-level device via the reading circuit 33.

When the tape runs in the forward direction and reaches the folding point of the tape, the lap mark WRAP1 on the forward side is read if the tape is normal (step S5). As a result, the wrap mark detection signal DWRAP is sent from the block / mark recognition circuit 34 to the controller 35, the drive unit 27 of the magnetic tape device 2 is controlled, and the running direction of the tape is reversed (step S8). Then, the tape running in the reverse direction is started, and the lap mark WR on the reverse direction side
When AP2 is detected (step S9), the reading of the recording data on the reverse side is continued (step S10).

If the forward lap mark WRAP1 is not detected in step S5,
Go to step S6, physical tape end marker FE
Forward tape feeding continues until OT is detected. When the physical tape end marker FEOT is detected (step S6), a reset process for temporarily stopping the tape feeding is performed (step S7), and then the tape running direction is reversed to start running in the opposite direction (step S7). Step S8).
By traveling in this reverse direction, the lap mark W on the reverse direction side
When RAP2 is detected (step S9), it is considered that the tape has been normally folded back, and reading of recorded data on the reverse side is continued (step S10).

On the other hand, in step S9, if the lap mark WRAP2 on the opposite side cannot be detected,
The process proceeds to step S11, and the forward lap mark WR
Check if AP1 is detected. When the wrap mark WRAP1 on the forward side is detected, the process proceeds to step S13, and when the data block on the reverse side is detected, it is determined that the data block is normally folded, and the process (step S10) is performed. continue.

If the data block DB on the reverse direction side cannot be detected in step S13, it is confirmed whether or not the tape mark TM can be detected in step S14. If the tape mark TM cannot be detected, either. When the tape has run for a specified length, it is determined to be an error (step S15), an error warning is issued in step S16, and the process ends abnormally.

If it is determined in step S11 that the forward lap mark WRAP1 is not detected, both lap marks WRAP1 and WRAP2 are missing, and this is a complete device error. , After issuing an error warning in step S12,
It ends abnormally.

When the tape is normally folded back, the recording data on the opposite side is read, and the magnetic head 21 passes the last data block DB, the tape mark TM indicating the end of the data block is detected (step S).
3). As a result, the tape mark detection signal DTM is sent from the block / mark recognition circuit 34 to the controller 35, and the tape mark (TM) process indicating that the reading of the data block is completed is executed (step S4).
When the data recording end marker EOD is detected, a series of data reading operation is completed.

[0022]

As described above, according to the magnetic tape reading method of the present invention, even if a medium defect in which a lap mark cannot be detected correctly occurs, the tape is correctly folded and data reading in the reverse direction is continued. This makes it possible to significantly improve the data reading performance of this type of magnetic tape device.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

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

FIG. 3 is a flowchart of the operation of the embodiment.

FIG. 4 is a diagram showing a recording format of a reciprocal recording type magnetic tape.

[Explanation of symbols]

 1 magnetic tape 2 magnetic tape device 3 magnetic tape control device 21 magnetic head WRAP1 forward wrap mark WRAP2 reverse wrap mark FEOT physical tape end marker

Claims (1)

[Claims] 1. A reciprocal recording type magnetic tape device in which a lap mark recorded at a folding point near the end of the tape is detected to fold the traveling direction of the tape, and no forward wrap mark is detected. In this case, the tape is returned to the physical tape end position of the magnetic tape, the tape is folded back, and reading of the recorded data on the reverse side is continued while the wrap mark on the reverse side is detected. If the lap mark is normal and the wrap mark on the reverse side is not detected, it is possible to continue reading the recorded data on the reverse side from the time when the wrap mark on the forward side is folded back. Tape reading method.