JPH0743852B2 - Block positioning control method in magnetic tape device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] A block positioning method for executing a backspace instruction in a magnetic tape device is provided with a block length information in a magnetic tape device for the purpose of performing block positioning in a magnetic tape device at high speed. When the backspace command is stored, the distance or time to backspace is calculated from the length information of the recorded block and the number of blocks to be backspaced, and the backspace command of the magnetic tape is calculated based on the calculation result. Configured to run.

[Field of Use of Invention]

The present invention relates to a magnetic tape device used as an external storage device in an information processing device, and more particularly to a block positioning control method in a magnetic tape device that records information in blocks.

A magnetic tape device is used as an external storage device of the information processing device.

This magnetic tape device stores information in blocks on a magnetic tape medium.

That is, the information is divided into blocks, the identification management information (ID) is recorded at the beginning, a block is composed of the information and the identification management information (ID), and a non-recorded part IBG) is provided and recorded.

In such a magnetic tape device,
There is an instruction called a backspace instruction that feeds the magnetic tape up to a plurality of recorded blocks and positions the magnetic head in a predetermined block, and it is required to execute this instruction at high speed.

[Conventional technology]

Conventionally, the following method has been adopted to execute the backspace instruction as described above.

That is, after advancing the magnetic tape in the reverse direction by a certain distance, the magnetic tape is sent in the forward direction to read the block, and it is determined whether or not the block is designated by the backspace command.

If the block indicated by the block is before that, advance the magnetic tape in the reverse direction for a certain distance, send the magnetic tape in the forward direction to read the block, and then instruct by the backspace command. If it is determined that the designated block is located in the front, it is equal to the designated block or until the designated block is determined to be located in the forward direction. repeat.

When it is determined that the block is equal to the block designated by the backspace command or is located in the forward direction from that position, the block is read in the forward direction and the magnetic head is positioned at the head position of the block designated. I was doing the action.

[Problems to be solved by the invention]

As described above, in the conventional method, when the backspace command is issued, the magnetic tape device does not have the backward reading function, and therefore the operation of advancing the magnetic tape in the backward direction for the predetermined fixed distance is performed. Since the control is performed by repeatedly searching for the head of the instructed block and positioning it, it takes a lot of time to process the backspace instruction, and there is a problem that the information processing apparatus is degraded.

An object of the present invention is to solve the above problems and perform block positioning control of a magnetic tape in response to a backspace instruction in a single time.

[Means for solving problems]

In order to achieve the above object, the present invention stores block length information in a magnetic tape device, and when a backspace command is received, the backspace is set based on the recorded block length information and the number of blocks to be backspaced. The power distance or time is calculated, and the backspace command of the magnetic tape is executed based on the calculation result.

[Work]

In the present invention, by pre-recording the block length information, it becomes possible to calculate the number of blocks to be backspaced by the backspace command and the distance / time to move the magnetic tape device from this block length. .

Therefore, by moving the magnetic tape using this operation result, it is possible to position the head of the block designated by the backspace instruction by moving the magnetic tape once.

As a result, the execution of the backspace instruction is accelerated as compared with the conventional case.

〔Example〕

FIG. 1 is a diagram for explaining the data format on the magnetic tape of the present invention.

In the figure, 1 is an ID part, 2 is a data part, 3 is a block,
4 shows IBG, respectively.

The block 3 is composed of a fixed length ID part 1 and a data part 2 as shown in the figure, and each block is divided by a fixed length IBG4.

The ID section 1 includes a data section 2 which is block identification and control information.
And the block number of the block 3 are recorded.

Such a block is divided and recorded by a fixed length IBG in the longitudinal direction of the magnetic tape.

The operation of the present invention will be described below based on the data format on the magnetic tape.

FIG. 2 is a diagram for explaining the operation of the magnetic tape device of the present invention.

Reference numeral 3 denotes a block similar to the block described with reference to FIG. 1, which is assumed to be recorded with a predetermined IBG interval in the longitudinal direction of the magnetic tape.

And the magnetic head is between the blocks of n + 4 and n + 5
It is assumed that the processing for the block n + 5 from the IBG has been completed, and the block is currently positioned at the IBG after n + 5 of the block 3 (positioned at the head of n + 6) and stopped.

The magnetic tape device recognizes and stores that it is currently positioned at the beginning of the block of n + 6.

In this state, it is assumed that a backspace command of 6 blocks is received from the host device to which the magnetic tape device is connected.

In that case, the actual position of the magnetic head is
Between blocks n-1 and n (positioned in block n)
Need to be positioned in IBG.

As will be described later, the length of one block on the magnetic tape is recognized in the magnetic tape device by the ID part of the block 3, calculated from the number of data bytes in the data part and other fixed constants and stored. ing.

Therefore, the distance or time to actually backspace the magnetic tape is calculated from this length information, and the backspace operation is started.

In this backspace operation, the backspace operation is performed for a distance or time corresponding to the number of blocks obtained by adding 1 to the number of blocks actually received by the instruction.

That is, the magnetic tape is run in the reverse direction to advance to the beginning of the n-1 block as shown in the figure, and then the magnetic tape is driven in the forward direction to read the n-1 block to recognize the block number. Then, the block number is compared with the previously recognized block number, and it is confirmed that the block is a block before the block designated by the backspace instruction.
Stop at IBG between and complete block positioning with backspace instructions.

As described above, according to the present invention, the backspace instruction can be executed by only one backspace operation of the magnetic tape, so that the backspace instruction can be completed in a single time as compared with the conventional case.

Next, referring to FIG. 3, a method of storing and calculating the block length on the magnetic tape will be described.

If one block is stored with the length of the ID part, the length of the data part, and the length of the IBG, the distance or time of the magnetic tape to be moved can be determined by multiplying this by the number of blocks.

First, since the length d of the ID part and the length c of the IBG4 are always fixed, they can be set in advance as constants.

Since the length of the data part 2 changes depending on the number of bytes in each file and the recording density of data,
It can be calculated by dividing the number of bytes of the data part 2 recorded in the ID part 1 by the recording density.

That is, assuming that the recording density is a and the number of bytes in the data section is d, the length of the data section can be calculated by d / a.

Therefore, the length L of one block is L = d / a + b + c.

Therefore, by storing the length L of this block in a register or the like, the operation described in FIG. 2 can be achieved.

Next, an embodiment for executing the backspace operation described in FIG. 2 will be described with reference to FIGS.

FIG. 4 is a diagram for explaining the configuration of the position embodiment of the magnetic tape device according to the present invention.

Reference numeral 10 denotes an interface register, which transmits / receives data to / from an upper device (not shown) and receives instructions and
This is for notifying the upper device of the completion of processing.

11 is a microprocessor that controls the entire magnetic tape device.

Reference numeral 12 is an external register for tape running control, and is for sending control information for controlling the running of the magnetic tape from the microprocessor 11.

Reference numeral 13 is an external register to which data to be recorded is sent out by a kind of DMA transfer through a buffer (not shown) provided in the interface register 10 under the control of a formatter 21 which will be described later. The data is set by the control of.

Reference numeral 14 is an external register for taking in data and transferring it to a higher-level device, and is for taking in the reproduced data reproduced from the magnetic tape to the microprocessor side.

Reference numeral 15 is a tape running control circuit for controlling a motor (not shown) for driving the reels 18 and 19 to run the magnetic tape under the control of the external register 12.

Reference numeral 16 is a recording circuit for modulating the recording data sent from the external register 13 according to a predetermined rule and sending it to the magnetic head 20 to record the data on the magnetic tape.

A reproducing circuit 17 reproduces the data on the magnetic tape by demodulating the data read by the magnetic head 20 from the magnetic tape.

Reference numeral 21 is a formatter for controlling the format for recording the data on the magnetic tape and separating the reproduced data according to a predetermined format.

22 is set a predetermined value from the microprocessor 11,
It is a timer for interrupting the microprocessor by calculating the time between them.

Reference numeral 23 is a ROM that stores a program for operating the microprocessor 11.

24 is a RAM provided in the microprocessor 11,
In this, various constants and the number of the block currently positioned are recorded.

In addition, 18 is a supply reel, 19 is a take-up reel, and 20 is a recording / reproducing magnetic head.

Next, the operation of the magnetic tape device of FIG. 4 according to the present invention will be described with reference to FIGS. 5 and 6.

FIG. 3 is an operation flowchart for explaining the block length recording operation according to the present invention.

Processing Step 100 This step is started when the magnetic tape device shown in FIG. 4 is brought into an operable state by performing a predetermined initialization process after the power is turned on.

After the processing step 101 is started, the interface register 10 continues to receive the command from the host device until the interface register 10 receives the command from the host device.

When the command is received, the process proceeds to the next step.

Processing Step 102 In this step, the received instruction is fetched into the microprocessor, and what kind of instruction the received instruction is is decoded.

The decoding of this instruction may be performed by software, or a decoder (not shown) may be used.

Processing Step 103 This step is to determine what the instruction from the host device is as a result of the instruction decoding in the processing step 102, and determine the next processing step.

That is, if the command is data recording / reproducing (read / write command), the process proceeds to step 105. If the command is a backspace command, the process proceeds to the process step shown in FIG. Proceed to processing step 104.

Process step 104 Process step 104 is a process of a part that is not related to the present invention, for example, a process for a file search command, a diagnostic command, etc., and is a process that is not related to the present invention. The description is omitted.

When this process ends, the process returns to step 101.

Processing step 105 If it is found in processing step 103 that it is a read / write command, in this step, a control signal for running the magnetic tape is set to the external register 12 by the microprocessor, and the tape running control circuit is set.
Drive 15 to start running the magnetic tape.

Process step 106 The magnetic tape is started to travel by process step 105,
When the magnetic tape reaches a predetermined speed, data recording / reproduction is performed on the magnetic tape.

That is, in the case of data recording, the data transferred from the host device is controlled by the formatter 21, for example, the predetermined block format shown in FIG. 1 is sent to the recording circuit 16 via the external register 13, And the data is recorded on the magnetic tape by the magnetic head 20.

In the case of reproducing data, the data reproduced from the magnetic tape via the magnetic head 20 is received via the external register 14 demodulated by the reproducing circuit 19, and unnecessary portions are controlled by the formatter 21. Is removed and only the desired data is transferred to the higher-level device via the interface register 10.

Then, the number of the block in which the magnetic head is currently located is recorded in the RAM 25 on the microprocessor 11.

Processing step 107 Then, the operation of this processing step 106 is continued until the end of one block, and when the recording / reproducing of one block is completed, the process proceeds to the next step.

Processing Step 108 In processing step 108, the block length of the block that has been recorded / reproduced is recorded.

That is, when the processing for one block is completed, the data of the ID part in the block is naturally discriminated by the control of the formatter 21, so the data of this ID part is fetched by the microprocessor 11 and is shown in FIG. ID part 1 explained
It is possible to determine the number of bytes d of the data part 2 in

Then, the block length L is calculated from the IBG length c, the ID length b, and the recording density a, which are already recognized as a fixed length and recorded on the RAM 25, as described in FIG. It is stored in the block length register 24 provided in the microprocessor 11.

L = d / a + b + c processing step 109 Then, in this step, it is judged whether or not all the blocks of the read / write command received by the command are completed,
Until the end, the processing step 106 to this step are repeated, and when the recording / reproducing of the data of all blocks is completed, the process proceeds to the next step.

Process step 110 When this step is reached, the process ends, and therefore the process returns to the process step 100.

The above is the operation for storing the block length.

In the above description, the block length is stored only at the time of reading / writing. However, for example, even when a file search command is executed, the block ID is read because the ID part of the block is read. It is possible to store it, and it is possible to perform the same processing as the above when executing the file search instruction.

In the above steps, when recording / reproducing data of a plurality of blocks with one command, the block length register 24 is updated at the end of recording / reproducing in each block. Does not change in one file, and recording / playback is performed only for blocks in one file in one command, so recording of the blotch length register once for one recording / playback command. ， Renewal only is acceptable.

In that case, the processing step 108 may be passed only once and then skipped for processing.

Next, the operation of backspace instruction execution according to the present invention will be described with reference to FIG. 6 using a flowchart.

This flow chart is executed when it is found that there is a backspace instruction as a result of instruction decoding from the host device in FIG.

Processing step 111 If it is found to be a backspace instruction, first, how many blocks are backspaced is recognized from the data stored in the interface register 10.

Explaining using the example of FIG. 2, there are 6 blocks in this case.

Process step 112 Next, the block length previously stored in the block length register 24 is read.

Process step 113 Next, the number of blocks to be backspaced and the running distance of the magnetic tape required for backspace are calculated based on the number of blocks to be backspaced obtained in process steps 112 and 113.

That is, in FIG. 2, since the number of back spaces is 6 and the block length is L, the traveling distance M is M = L × (6 + 1).

The number of backspaces is incremented by 1 for the reason described in FIG.

Then, the calculated traveling distance M is temporarily stored in the RAM in the microprocessor 11.

Process step 114 Next, the required travel distance calculated in process step 113 is converted into the running time of the magnetic tape.

That is, in the magnetic tape device of FIG. 4, since the magnetic tape is driven only by the drive motor of the reel, the traveling distance cannot be accurately grasped. In this embodiment, therefore, the traveling distance is not controlled but the time is controlled. To do.

However, when the magnetic tape device is driven by a capstan or the like, the accurate traveling distance of the magnetic tape can be known, so the value obtained in the processing step 114 can be used as it is.

Here, the running speed of the magnetic tape device is known in advance.

That is, assuming that the running speed of the magnetic tape is N (inch) / second, the running time is determined by dividing the tape running distance M (inch) stored in the previous step by this N (inch). .

Process step 115 The time calculated in process step 114 is set in the timer 22.

Processing step 116 Then, the microprocessor 11 issues a control signal to the external register 12 to drive the motor (not shown) of the reels 18 and 19 by the tape running control circuit 15 to start moving the magnetic tape in the reverse direction. Start timer 22.

Process Step 117 In this process step, the process loops until the timer 22 detects a timeout, and when the timeout is detected, the process proceeds to the next step.

Processing Step 118 At the time of entering this step, in FIG.
Since the magnetic tape has advanced to the IBG before n-1, the microprocessor 11 at this point issues a control signal to the external register 12 to cause the tape running control circuit 15 to drive the motor (not shown) of the reels 18 and 19. The magnetic tape is driven to start moving in the forward direction.

Processing step 119 Then, in this step, the ID section of the block n-1 in FIG. 2 is read from the magnetic tape via the magnetic head 20 and the reproducing circuit by the control of the formatter 21, and is read. The block number that was previously recorded in the RAM 25 of the microprocessor 11 is compared with the ID number of the block at the time of starting the backspace, and it is confirmed whether the block is one block before the block to be positioned by the backspace instruction. .

Processing step 120: By checking the block number in processing step 119, n
Since -1 is confirmed, if the drive stops at the point of the next IBG, it is the previous IBG of the desired block n. At this point, the tape running control circuit 15 transfers the magnetic tape of the magnetic tape via the external register 12. Stop running.

Processing step 121 Then, in this state, the execution of the backspace instruction is completed, and the completion of the execution is directed to the host device via the interface register 10, and the processing is completed.

〔effect〕

As described above, according to the present invention, the execution of the backspace instruction is stored as the block length, the distance or time for backspace is calculated based on this block, and the magnetic tape is run. In comparison, positioning of blocks by backspace operation can be completed in a single time.

[Brief description of drawings]

1 is a diagram for explaining the data format on the magnetic tape of the present invention, FIG. 2 is a diagram for explaining the operation of the magnetic tape device of the present invention, and FIG. 3 is a diagram for explaining the magnetic tape block length of the present invention. FIG. 4 is a block diagram of an embodiment of a tape device according to the present invention, FIG. 5 is a block length recording operation flowchart according to the present invention, and FIG. 6 is a backspace instruction execution flowchart according to the present invention. . Further, in the figure, 1 is an ID part, 2 is a data part, 3 is a block, 4 is an IBG, 11
Indicates a microprocessor, and 24 indicates a block length register.

Claims (3)

[Claims] 1. A magnetic tape device for recording data in block units on a magnetic tape, wherein the magnetic tape device stores block length information, and when a backspace command is received, the recorded block length. A block positioning in a magnetic tape device, characterized in that a distance or time to be backspaced is calculated from information and the number of blocks to be backspaced, and a backspace command of the magnetic tape is executed based on the calculation result. Control method. 2. The block length information is stored while the magnetic tape device is recording / reproducing data and executing a file search command. A block positioning control method in a magnetic tape device. 3. The block comprises an ID section and a data section, and the ID section is constructed by recording at least a block number and the number of bytes of the data section. 2. A block positioning control method in a magnetic tape device according to claim 1.