JP2625796B2 - Magnetic tape unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Summary] The present invention relates to a magnetic tape device of the serpentine system, which aims to perform high-speed block positioning in a magnetic tape device, and stores information of the last block of each data track on the magnetic tape, and executes a block positioning command. Upon reception, the data track to be positioned is recognized based on the stored information, and after positioning the magnetic head on the data track, the magnetic tape is run and the command is executed by positioning the magnetic tape in a predetermined block. Configured. 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 serpentine type magnetic tape device. A magnetic tape device is used as an external storage device of the information processing device. In such a magnetic tape device, a magnetic tape recording method called a serpentine method has recently been adopted. The serpentine system does not collectively record / reproduce a plurality of data tracks on a magnetic tape, but forms one logical track with one or several physical tracks. The head is sought in the width direction of the magnetic tape to record / reproduce data. That is, first, data is recorded / reproduced from the beginning to the end of the magnetic tape in units of one logical track on the magnetic tape, and then the tracks are switched to record / reproduce data from the end of the magnetic tape to the beginning. By reproducing and repeating this, data is recorded / reproduced on the magnetic tape. Further, this magnetic tape device stores information on a magnetic tape in block units. That is, information is divided into blocks, identification management information (ID) is recorded at the beginning of the information, and a block is formed from the information and the identification management information (ID). IBG). In such a magnetic tape device, it is desired that the execution of the block positioning command is completed in a short time when the block positioning command is received from the host device. [Prior Art] In a magnetic tape device adopting the above-mentioned serpentine recording method, when a block positioning command is received, conventionally, a block is positioned by the following method. That is, when a block positioning command is received from a higher-level device while the magnetic tape is positioned at a predetermined position on a desired track of the magnetic tape medium, the block to be positioned is located at a position before the own position or at a position after the block. Thus, the running direction of the magnetic tape is determined, the magnetic tape is run in the determined direction, the identification management information (ID) is read for each block, and it is checked whether the ID matches the ID of the desired block. . This search process is continued until a desired block is found. [Problems to be Solved by the Invention] However, in such a serpentine magnetic tape device, when a block to be positioned by a block positioning command is not in the same data track, As described above, since the search is continued until the desired block is found as described above, the processing of the block positioning command is not completed until after the magnetic tape has been run several times the total tape length, and the block positioning command is not completed. Processing takes a very long time. In particular, in the method of reading and checking the ID for each block as described above, if the block to be positioned is located behind its own position, such as a command related to backspace, the magnetic tape is moved backward by one block. A search operation of running and stopping, and then running forward and reading and checking the ID of the immediately preceding block is required, and there has been a problem that the processing time is extremely enormous. SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic tape device which solves the above-mentioned problem and can execute a block positioning command in a single time. [Means for Solving the Problems] To achieve the above object, the present invention provides a magnetic tape device, comprising: a storage unit for storing information of the last block of each data track on a magnetic tape; Upon receiving the positioning command, the recognition unit for recognizing the data track where the block to be positioned based on the stored information is located, and the magnetic head were positioned when the execution of the block positioning command was started. A head drive unit that moves from a location in the width direction of the magnetic tape to position the recognized data track; and, after the magnetic head is positioned at the recognized data track, moves the magnetic tape to position the magnetic tape. And a tape drive unit positioned at a power block. [Operation] In the present invention, by storing the information of the last block of each track, upon receiving the block positioning command, the block to be positioned is located in any data track by referring to the stored information. Can be determined. Therefore, at first, the magnetic head is moved to the data track in the width direction of the magnetic tape to be positioned, and then only the block to be positioned in the data track is searched for.
Execution of the instruction can be completed. Therefore, at worst, the running length of the magnetic tape is within the range of the entire length of the magnetic tape, and the positioning of the block can be completed in a single time as compared with the related art. FIG. 1 is a diagram for explaining a data format of one data track on a magnetic tape according to the present invention. In the figure, 1 is an ID part, 2 is a data part, 3 is an IBG, 4
Indicates a data block and 5 indicates a file mark block. The block 4 includes a fixed-length ID section 1 and a data section 2 as shown in the figure. Each block is divided by a fixed-length IBG 3. The ID section 1 includes a flag bit indicating that the data block is block identification and control information, a file number (for example, 2 bytes), a block number (for example, 3 bytes) in the file, and the number of bytes of the data section 2. Has been recorded. Such a data block 4 is recorded by being divided by a fixed length IBG in the longitudinal direction of the magnetic tape. Further, the file mark block 5 is substantially composed of only an ID part of a data part, and a flag bit indicating a file mark and a file number indicating a file number in the tape are recorded. “0” is recorded. Next, a data recording method of a magnetic tape device using a serpentine method which is a magnetic tape device according to the present invention will be described with reference to FIG. In the figure, reference numeral 6 denotes a magnetic tape, and 7 denotes a data track. On the magnetic tape 6, for example, 0 to 0
Suppose there are 15 tracks. As described above, the concept of a logical track is a unit in which one logical track is recorded at a time, and is physically composed of one or several tracks. For convenience of explanation, the following description is based on the assumption that one logical track is one physical track. As shown in the figure, it is assumed that a total of 16 tracks 0 to 15 exist on the magnetic tape 6 in the width direction of the tape (up and down in the drawing). Then, from the track at the end in the width direction of the tape 6, 0
~ 15 track numbers are assigned. On such a magnetic tape 6, data is recorded from the beginning of the track 0 to the end of the magnetic tape 6 in a block format as described in FIG. When data recording is completed up to the end of the magnetic tape 6, the magnetic tape is temporarily stopped at that time, and a magnetic head (not shown) is moved and positioned in the width direction of the magnetic tape 6, and this time, the magnetic head is positioned on the track 1. This time, data is recorded on the track 1 while running the magnetic tape 6 from the end of the magnetic tape 6 to the start end. Then, when the magnetic tape 6 reaches the start end, the magnetic tape is temporarily stopped at that time, a magnetic head (not shown) is moved and positioned in the width direction of the magnetic tape 6, and then the magnetic head is positioned on the track 2, and this time. Record data by running the magnetic tape 6 from the beginning to the end of the magnetic tape 6 as in the case of the track 0. As described above, the magnetic tape 6 is moved alternately from the starting end to the end and from the end to the starting end while the magnetic head is sequentially moved and positioned on each track to record information. In such a magnetic tape device, in the present invention, information of the last block of each track on the magnetic tape 6 is stored in a storage element provided in the magnetic tape device. That is, in the track 0, the information of the last block recorded before switching to the track 1 is recorded on the end side of the magnetic tape, and then in the track 1, the information of the magnetic tape 6 is recorded.
The information of the last block recorded before switching to the track 2 is recorded at the start end of the data track, and the information of the last block in each data track is sequentially stored. That is, the block information records the file number and the block number in the file. In this way, it is possible to determine the stored information as to which block of which file is recorded on which data track. The file number in the block ID portion is a serial number from the beginning of track 0 to the end of the last track, and the block number is assigned from 1 in the same file from the beginning of the data block with the file mark being 0. No block number straddling is given. The recording format of this block information will be described later. Next, a block positioning method according to the present invention using the block information will be described with reference to FIG. First, it is assumed that information of the last block recorded on each data track is stored in the magnetic tape device as described with reference to FIG. In this state, it is assumed that the magnetic head is currently located at a predetermined position on the data track 4. In this state, when a block positioning command is issued from the host device, the block positioning command is executed as follows in the present invention. The block positioning instruction is, for example ,. Since the instruction comes in the form of the previous file or in the form of positioning multiple blocks before, the block position command received first receives the current position of the block and the information obtained by this command. Then, the file or block number to be actually positioned is calculated. Next, in order to recognize on which data track the file or block number to be actually located is located, the last block information of each data track previously stored is referred to. Then, a data track whose relation between the information of the last block and the block to be positioned meets the following conditions is searched. That is, the relationship between blocks and file numbers between adjacent data tracks is as follows: (information of last block of previous track) <(information of target block) <(information of last block of subsequent track)
Find a data track that satisfies the relationship. As a result of the finding, when there is a block to be positioned on the track 1, the magnetic head is moved by the track selection as indicated by the arrow, and the position of the block is determined. As described above, the magnetic tape is read and recognized in the forward direction, and as a result, when the magnetic tape is ahead, the magnetic tape is moved as it is, and positioned and stopped at the target block. That is, the gist of the present invention is to enable the positioning of the blocks on the magnetic tape in a short time by enabling the selection of the track on the magnetic tape first. Next, referring to FIG. 4, an embodiment of a magnetic tape apparatus for carrying out the method of the present invention will be described. In FIG. 1, reference numeral 10 denotes a microprocessor, which has a program ROM therein, and controls driving of a magnetic tape, recording / reproducing of data on the magnetic tape, and selection of a track of a magnetic head by an instruction from a host device. . 11 receives the control signal from the microprocessor,
This is a tape running control circuit for controlling the running of the magnetic tape by driving a motor (not shown) for driving the reels 232 and 24. A signal 12 from a detector 27 for detecting the start and end markers of the magnetic tape and a rotation detection signal from the reels 23 and 24 are input to detect the start and end of the magnetic tape and to detect the start and end of the magnetic tape. And that the magnetic head is located near the end,
Is a tape position detection circuit for notifying the user. When approaching the beginning or end of the magnetic tape,
It is determined from the tape winding ratio of the reels 23 and 24. Reference numeral 13 denotes a recording system for converting data transferred from the host device into a predetermined data format under the control of a format control circuit 16 described later, and performing predetermined modulation to record the data on the magnetic tape 6 via the magnetic head 26. Circuit. Reference numeral 14 denotes a reproducing circuit for demodulating a signal reproduced from the magnetic tape 6 via the magnetic head 26, separating data under the control of a format control circuit 16 described later, and transferring the data to a higher-level device. Reference numeral 15 denotes a head drive circuit for moving the magnetic head 26 in the width direction of the magnetic tape 6 and controlling the mechanism 25 to select a track, thereby moving and positioning the magnetic head to a desired data track. It operates under the control of the processor 11. Reference numeral 16 denotes a format control circuit, which constitutes a block for recording on a magnetic tape, and is used for adding a desired correction code or adding a file number or a block number to a block ID portion. . The microprocessor is provided with the following registers and table memory for recording data for use in the present invention. A track number register 17 is a register for storing the number of the data track where the magnetic head is currently located. Reference numeral 18 denotes a current block number register for storing the number of the block where the head is currently positioned. Reference numeral 19 denotes a current file number register for storing the number of the file in which the magnetic head is currently positioned. Reference numeral 20 denotes a block length register for storing information on the length of the block in which the magnetic head is currently positioned. Reference numeral 21 denotes a table memory for storing a file number and a block number of the last block recorded on each data track. Reference numeral 22 denotes a RAM, which is a work area for performing calculations and processing for determination. Next, in FIG. 5, the table memory in FIG.
The configuration of 21 will be described. As shown in the figure, the table memory has areas corresponding to the number of data tracks, and each area has an area for storing a file number and a block number. Next, the operation of the magnetic tape device in FIG. 4 will be described using a processing flowchart. FIG. 6 is a diagram for explaining a command decoding unit processing flowchart according to the present invention. After the power is turned on and the initialization of the magnetic tape device is completed, the microprocessor 11 takes an instruction receivable state from the host device, and the processing steps in FIG. 6 are started. Processing Step 100 In the processing step 100, an interface register with the higher-level device provided in the microprocessor 10 is constantly monitored whether an instruction from the higher-level device is received. In this state, the process moves to the next step when a command is received from the host device. Processing Step 101 In this step, what kind of instruction the previously received instruction is is decoded in the microprocessor 10. Processing Step 102 In this step, the contents of the decoded instruction are separated into the direction in which the magnetic tape runs, and other diagnostic instructions are separated. In the case of another instruction, the process proceeds to the processing step 103, where the other instruction is executed, and returns to the initial state. If the command is for a forward running command of the magnetic tape, the process proceeds to processing step 104. On the other hand, if the command is for a reverse direction command for the magnetic tape, the process proceeds to steps described later with reference to FIG. The reverse direction command includes a backspace command, and includes a backspace file command and a backspace block command. Processing step 104 If the preceding processing step 102 is a command relating to the forward running of the magnetic tape, this command includes a data read / write command, a space file command, and a block space command. 3
It separates two instructions. That is, in the case of a data read / write instruction,
The process proceeds to the processing steps shown in FIG. In the case of a space file instruction,
The process proceeds to the processing steps shown in FIG. If the instruction is a block space instruction, the process proceeds to the processing steps shown in FIG. The above is the processing related to instruction decoding. Next, a block space instruction processing flowchart according to the present invention will be described with reference to FIG. Processing Step 200 First, the microprocessor 10 writes the block number where the magnetic head is currently located from the register 18 into the RAM 22. Processing Step 201 Then, a target block number is calculated from the number of blocks to be skipped specified by the block space instruction and the current block number read in the previous step. Then, the calculated block number is stored in the RAM 22 of the microprocessor 10, and the process proceeds to the next step. Processing step 202 In processing step 202, the microprocessor 10
By issuing a control signal to the tape running control circuit 11 more,
Start running the magnetic tape in the forward direction. Processing Step 203 When the running of the magnetic tape is started, the microprogram 10 determines whether the start (BOT) end (EOT) of the magnetic tape is detected from the marker 27 by the tape position detection circuit 12, and If it is detected, the table memory recording routine 300 is executed next. If not, proceed to the next step. Processing Step 204 In this step, first, it is detected whether a block is detected. If no block has been detected, the process returns to processing step 202. If a block has been detected, proceed to the next step. The microprocessor 10 can detect a block by detecting a predetermined block pattern by the reproducing circuit 14 and the format control circuit 16. Processing Step 205 If a block is detected in the previous step, then the format control circuit 16 separates and recognizes the ID part of the block, and reads the block number into the RAM 22. Processing Step 206 The block number read in the previous step is
Once stored in the RAM 22, the contents of the current block number register 18 are updated with this block number. Processing step 207 and the target block number stored in the RAM 22;
The current block numbers are compared, and if they match the target, the process proceeds to the next step.
Return to 2. Processing step 208 If the target block and the current block number match in processing step 207, the microprocessor 10
A signal is issued to the tape running control circuit 11 to stop the running of the magnetic tape. Processing Step 209 Then, the completion of the execution for the block space instruction is reported to the host device, and this processing ends.

[Table Memory Recording Routine 300] If the start and end of the tape are detected in the previous processing step 203, it is necessary to store the information of the last block of the data track according to the present invention, and the track switching of the magnetic head is performed. Since the operation needs to be performed, the following processing is performed. This routine is a subroutine, and is used in other processes. In the present invention, this routine is called a table memory recording routine for the sake of convenience. However, only the processing steps 302 and 303 are actually added in the present invention, and the other steps are conventional. Processing Step 301 First, upon detecting the start / end of the tape, the microprocessor 10 issues a control signal to the tape running control circuit 11 to stop the running of the tape. Processing Step 302 In this processing step, the contents of the current block number register 18, the current file number register 19, and the current track number register 17 in the microprocessor 10 are read. Processing Step 303 In this step, the address of the recording area of the track is specified by the contents of the current track number register 17 read out from the previous step of the table memory 21, and the current block number register 1 read out in the previous step is read out.
8. The contents of the current file number register 19 are stored in the table memory 21. By this processing, information of the last block can be recorded when located at the end of the data track. Processing step 304 Next, when the recording to the table memory is completed, the microprocessor 10 issues a head switching signal to the head driving circuit 15, drives the switching mechanism 25, and moves the magnetic head 26 to the next track. Position. Then, the current track number register is updated. Processing step 305 and the microprocessor 10
A reversal instruction is issued to 11 so that the tape running direction is reversed. The above is the table memory recording routine. In the case of FIG. 7, after executing this routine, step 20 is executed.
Return to 2. Next, a flowchart of the read / write instruction processing according to the present invention will be described with reference to FIG. Processing Step 400 In this step, each part of the microprocessor 10 is set in a processable state in order to record / reproduce data on / from the magnetic tape. Processing Step 401 Next, the microprocessor 10
Is instructed to drive the tape, and the running of the magnetic tape is started. Processing Step 402 In this processing step, first, when the running of the magnetic tape is started, it is detected from the signal from the tape position detection circuit 12 whether or not the magnetic tape is in the vicinity of the start / end of the magnetic tape. That is, if the magnetic tape is traveling from the start end to the end, it is determined whether the magnetic tape is in the area near the end.If the magnetic tape is traveling from the end to the start, the area is in the area near the start. This is for recognizing whether or not each of the reels is present, which can be detected by rotation detection signals from the reels 23 and 24. If it is detected that it is near the start / end of the magnetic tape, the process proceeds to processing step 408. Otherwise, go to the next step. Processing Step 403 In this step, the running of the magnetic tape is started, and it is determined from the signal from the tape position detecting circuit 12 whether or not the start and end of the magnetic tape are detected by the marker 27. If so, the process proceeds to the table memory recording routine of processing step 300, and if not, the process proceeds to the next step. Processing Step 404 In this step, running of the magnetic tape is started,
Upon reaching the predetermined speed, the microprocessor drives either the recording circuit 13 or the reproducing circuit 14 and the format control circuit 16 to start recording and reproducing data in block units. Processing step 405 and processing step 404 are continued until recording / reproduction of data in units of one block is completed, and the processing proceeds to the next step upon completion. Processing Step 406 In this step, the recording /
The data of the reproduced block is stored in the microprocessor 10
The current block number register 18, the current file number register 19, and the block length register 20 are updated using this data. The block length register is calculated and calculated from the number of bytes of the data part in the ID part of the block. Processing Step 407 In the processing step 406, it is determined whether the recording / reproduction of data has been completed for all blocks by the read / write command. If all the designated blocks are completed,
If the processing is completed and there are still blocks to be recorded / reproduced, the process proceeds to processing step 400. Processing Step 408 In processing step 408, this step is entered because it is located near the start / end of the magnetic tape. However, in the case of data reproduction, it is necessary to reproduce the data until the start / end of the magnetic tape is detected. In the case of data recording, however, the start / end of the magnetic tape is always required.
Data recording must be completed before the end is detected. Therefore, in this step, it is determined whether the instruction is data recording / reproduction. If the instruction is a recording, the process proceeds to a processing step therefor. Return to 403. Processing Step 409 If the vicinity of the start / end of the magnetic tape is detected during the data recording, the microprocessor 10 reports to the host device that it is near the start / end of the magnetic tape, and the data recording is interrupted once. Foretell. Processing Step 410 In processing step 410, the same step is executed in the part related to recording in processing step 404. Processing step 411 Performs the same processing as processing step 405. When this process is completed, the same process as the process step 406 is performed, and then the table recording routine described above is operated. Then, the process proceeds to the post-process step 407. The above is the read / write instruction processing. Next, a file space instruction processing flow according to the present invention will be described with reference to FIG. Processing step 500 In this step, the microprocessor 10
Read the current file number from 19. Processing step 501, the file number read in the previous step,
The file number to be spaced by the instruction and the target file number are calculated. Processing Step 502 The microprocessor 10 issues a control signal to the tape running control circuit 11 to start driving the magnetic tape. Processing Step 503 In this step, a tape position detection circuit determines whether the start / end of the magnetic tape is detected by the marker 27.
Detected by the microprocessor 10 from the twelve output signals. If not detected, the process proceeds to the next step. If detected, the process proceeds to the table memory recording routine 300. Processing Step 504 In this step, it is determined whether a block is detected.
If the block is detected by the reproduction circuit 14 and the format control circuit 16 and the microprocessor 10 recognizes the block, the process proceeds to the next step; otherwise, the process returns to the processing step 502. Processing Step 505 In this processing step, the ID part of the block recognized in the previous step is read and recorded in the RAM 22 of the microprocessor 10. Processing Step 506 It is determined from the flag information of the flag ID part whether the block is a file mark block or a data block based on the ID part of the block read in the previous step. If it is a file mark block, the processing step
Proceeding to 508, if it is a data block, proceed to processing step 507. Processing step 507 If it is determined in the previous step that the data block is a data block, in this step the block number is recognized from the data of this ID part and the current block number register
Update the contents of 18. Processing Step 508 If it is determined in the preceding step that the block is a file mark block, the file number is recognized from the data of this ID part in this step, and the contents of the current file number register 19 are updated. Processing Step 508 In this step, it is determined whether the file mark block is the target file first by comparing it with the target file number previously stored in the RAM 22. If the result of the determination is that the file number is different from the target file number, the process returns to processing step 502. If it is the target file number, go to the next step. Processing Step 509 Since the magnetic head is positioned at the target file in the upper step, the microprocessor 10 issues a control signal to the tape running control circuit 11 to stop the running of the magnetic tape. Processing Step 510 Then, in this step, the completion of the execution of the file space instruction is reported to the host device. The above is the processing flow of the file space instruction execution. Next, the backspace instruction processing flow according to the present invention will be described with reference to FIG. As described in the instruction decoding process in FIG. 6, there are two backward traveling-related instructions. That is, one is a backspace file instruction and the other is a backspace block instruction. Processing Step 600 In this step, first, it is determined whether the instruction is a backspace file instruction or a backspace block instruction. If the result of the determination is that the command is a backspace file command, the process proceeds to the process described in FIG. If it is a backspace block instruction, the process proceeds to the next step. Processing step 601 The microprocessor 10 sets the current block number register
The current block number and the current file number are read from the current file number register 18 and the current file number register 19 and stored in the RAM 22. Processing Step 602 The microprocessor 10 calculates a target block number from the number of blocks to be backspaced received by the instruction and the current block number on the RAM 22, and records the target block number on the RAM 22. Processing Step 603 The microprocessor 10 determines the number of the data track on which the block of the target block number is recorded with reference to the table memory 21 based on the target file number and the block number. Processing step 604 The microprocessor 10 issues a control signal to the head drive circuit 15 according to the data track number determined in the previous step, drives the head drive mechanism 25, and moves and positions the magnetic head 26 to the target track. I do. The microprocessor 10 has a track number register
Update the contents of 17. Processing Step 605 The microprocessor 10 issues a drive signal to the tape running control circuit 11 to move the magnetic tape in the forward direction. Processing Step 606 The microprocessor 10 controls the reproduction circuit 14 and the format control circuit to control the ID of the read block.
The part is read and stored in the RAM 22. Processing Step 607 The microprocessor 10 updates the current block number register 18, the current file number register 19 and the block length register 20 based on the data of the ID part stored in the RAM 22 in the previous step. Processing Step 608 Based on the data read into the RAM 22 in the previous step, the microprocessor 10 determines whether the file is in the same file as the target block. If the files are in the same file, the process proceeds to the next step. If the file is not in the same file, the process proceeds to processing step 611 if the file is positioned before the target, and if the file is positioned in a file after the target, the process proceeds to processing step 613. move on. Processing Step 609 If the magnetic tape is positioned in the same file as the target file first, the target block is determined. That is, if it matches the target block, the process proceeds to the next step. If the block is positioned before the target block, the process proceeds to processing step 615. If the block is positioned after the target block, the process proceeds to processing step 617. Processing Step 610 As described above, when the processing is completed, a completion report is issued to the higher-level device, and the present processing ends. Processing Step 611 In the processing step 611, since the file is positioned in the file before the target file, the microprocessor 10
Issues a command to the tape running control circuit 11 to stop the magnetic tape immediately to stop the running of the magnetic tape. Then, the difference between the current file position and the target file is calculated by the microprocessor 10, and based on the calculated value, the microprocessor 10 issues a file space instruction in the same manner as the file space instruction from the host device. Then, in a processing step 612, a file space processing routine 612 is executed. This routine is the same as that described with reference to FIG. When the processing of this routine is completed, the process returns to processing step 605. Processing step 613 In processing step 613, since the file is positioned in a file after the target file, the microprocessor 10
Issues a command to the tape running control circuit 11 to stop the magnetic tape immediately to stop the running of the magnetic tape. Then, the difference between the current file position and the target file is calculated by the microprocessor 10, and based on the calculated value, the microprocessor 10 executes the backspace file instruction in the same manner as the backspace file instruction from the host device. Is issued, and a backspace file processing routine is executed in the next processing step 614. Since this processing routine is almost the same as the conventional processing,
Although the details are omitted, the magnetic tape is run in the reverse direction for a fixed length, and then the magnetic tape is run in the forward direction to read the blocks repeatedly until a target file mark is found. Processing Step 615 In the processing step 615, in the previous routine, since it is necessary to forward the magnetic tape to search for the target block because it is located in the block before the target block, the number of blocks to be spaced Is calculated,
Issued as an instruction format that is almost the same as the block space instruction from the host device, the block space processing routine 61
Step 6 causes block space processing to be performed. This block space processing is the same as the processing described in FIG. Processing Step 616 In processing step 616, the number of blocks to be spaced is determined because the magnetic tape needs to be sent in the reverse direction to search for the target block because it is located in the block after the target block in the previous routine. Is calculated,
It is issued as an instruction format substantially the same as the backspace block instruction from the host device, and the backspace block processing routine 618 performs block space processing. For this backspace processing routine, the method described in Japanese Patent Application No. 62-333138 filed by the present inventors on the same filing date may be used, or a conventional method may be used. Then, when these processes are completed, a process step 610 is performed.
In, the completion direction is performed to the host device, and the process ends. Next, the processing of the present invention for a backspace file instruction will be described with reference to FIG. The processing of the backspace file instruction is determined by processing step 600 in FIG. 10, and this step is started. Processing Step 700 The microprocessor 10 reads the file number where the magnetic head is currently located from the current file number register 19 and writes it to the RAM 22. Processing Step 701 The microprocessor 10 calculates a target file number from the number of files to be backspaced received by the instruction and the current file number on the RAM 22, and records the target file number on the RAM 22. Processing Step 702 The microprocessor 10 determines the number of the data track on which the block of the target file number is recorded by referring to the table memory 21 based on the target file number. Since the file number may be recorded over a plurality of data tracks depending on the number of blocks in the file, if there are a plurality of files having the same file number, it is necessary to position the file at the head of the file. , The data track located at the top is selected. Processing step 703 The microprocessor 10 issues a control signal to the head drive circuit 15 according to the data track number determined in the previous step, drives the head drive mechanism 25, and moves and positions the magnetic head 26 to the target track. I do. The microprocessor 10 has a track number register
Update the contents of 17. Processing Step 704 The microprocessor 10 issues a drive signal to the tape running control circuit 11 to move the magnetic tape in the forward direction. Processing Step 705 The microprocessor 10 controls the reproduction circuit 14 and the format control circuit to control the ID of the read block.
The part is read and stored in the RAM 22. Processing Step 706 The microprocessor 10 updates the current block number register 18, the current file number register 19, and the block length register 20 based on the data of the ID part stored in the RAM 22 in the previous step. Processing Step 707 Based on the data read into the RAM 22 in the previous step, the microprocessor 10 determines whether the file number is the same as the target file number. If it is the same as the target file, the process proceeds to the next step. If the target file is not a target file but a file before the target file, the processing step 71
The process proceeds to 0, and if the file is positioned in a file after the target file, the process proceeds to processing step 712. Processing step 708 If the magnetic head is located in the same file, then it is necessary to position the magnetic head at the beginning of the file mark at the beginning of the file.
In the processing step 609 in FIG. 10, the same processing is executed by designating the target block number to 0, and the same processing is executed as this file positioning processing routine to be positioned at a predetermined file mark, and the processing ends. Processing Step 710 In processing step 710, since the file is positioned before the target file, the microprocessor 10
Issues a command to the tape running control circuit 11 to stop the magnetic tape immediately to stop the running of the magnetic tape. Then, the difference between the current file position and the target file is calculated by the microprocessor 10, and based on the calculated value, the microprocessor 10 issues a file space instruction in the same manner as the file space instruction from the host device. Then, a file space processing routine is executed in processing step 711. This routine is the same as that described with reference to FIG. When the processing of this routine is completed, the process returns to processing step 709. Processing Step 712 In processing step 712, since the file is positioned after the target file, the microprocessor 10
Issues a command to the tape running control circuit 11 to stop the magnetic tape immediately to stop the running of the magnetic tape. Then, the difference between the current file position and the target file is calculated by the microprocessor 10, and based on the calculated value, the microprocessor 10 executes the backspace file instruction in the same manner as the backspace file instruction from the host device. Is issued, and a backspace file processing routine is executed in the next processing step 713. Since this processing routine is almost the same as the conventional processing,
Although the details are omitted, the magnetic tape is run in the reverse direction for a fixed length, and then the magnetic tape is run in the forward direction to read the block repeatedly until a target file mark is found. Processing Step 709 As described above, when the processing is completed, a completion report is issued to the higher-level device, and the present processing ends. With the above configuration, it is possible to switch the track of the magnetic head 26 by referring to the table memory 21 particularly in the processing related to the back space, so that the positioning of the block is performed in a short time. It becomes possible. Although the positioning of the backspace block is omitted in the above description, it will be briefly described here. The operation of the present invention will be described below based on a data format on a magnetic tape as shown in FIG. As described above, the microprocessor 10 is provided with the block length register 20, and recognizes the current length of one block on the magnetic tape from the ID portion of the block, and determines the number of data bytes in the data portion. And other fixed constants. Accordingly, the distance or time to actually backspace the magnetic tape is calculated from the length information, and the operation starts the backspace operation. 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, assuming that the target block number is n, the magnetic tape is run in the reverse direction and the target block number (n)
Then, the magnetic tape is driven forward to read the block of the block number (n-1) to recognize the block number by driving the magnetic tape in the forward direction. Is compared with the previously recognized block number, and recognizes that the block is located before the block designated by the backspace instruction, and compares the block with the block number (n-1) and the block with the block number (n). It is sufficient to stop at the IBG during the period and complete the block positioning by the backspace instruction. Next, a method of storing and calculating the block length will be described. If one block is stored with the length of the ID section, the length of the data section, 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 portion and the length c of the IBG4 are always fixed lengths, they can be set as constants in advance. Since the length of the data portion 2 varies depending on the number of bytes in a file unit and the recording density of data, the length can be calculated by dividing the number of bytes of the data portion 2 recorded in the ID portion 1 by the recording density. . That is, if the recording density is a and the number of bytes of the data part is d, the length of the data part can be calculated by d / a. Therefore, the length L of one block is L = d / a + b + c. Therefore, the operation described above can be achieved by storing the length L of this block in a register or the like. [Effect] As described above, according to the present invention, by referring to the table memory 21 at the time of receiving the block positioning command, it is possible to know how many tracks the track in which the block to be positioned is recorded is away from the current track. Can be. Therefore, by moving the magnetic head 26 in the width direction of the magnetic tape 6, it is possible to position the target track in a short time, and thereafter, the execution of the instruction is completed only by searching for a block to be positioned in the track. be able to. Therefore, at worst, the running length of the magnetic tape is within the entire length of the magnetic tape, and the positioning of the block can be completed in a short time. In particular, in the process related to the back space, the track switching of the magnetic head 26 can be performed by referring to the table memory 21, so that the block can be positioned in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a data format on a magnetic tape of the present invention, FIG. 2 is a diagram for explaining a data recording method of a magnetic tape device according to the present invention, and FIG. 3 is an operation of the magnetic tape device of the present invention. FIG. 4 is a configuration diagram of an embodiment of a magnetic tape device according to the present invention. FIG. 5 is a diagram illustrating a memory table configuration according to the present invention. FIG. 6 is an instruction decoding unit process of the present invention. FIG. 7 is a block space instruction processing flowchart according to the present invention, FIG. 8 is a read / write instruction processing flowchart according to the present invention, FIG. 9 is a file space instruction processing flowchart according to the present invention, and FIG. FIG. 11 is a backspace command processing flowchart according to the present invention, and FIG. 11 is a backspace file command processing flowchart according to the present invention. In the figure, 1 is an ID part, 2 is a data part, 3 is an IBG, 4 is a block, 10
Is a microprocessor, 17 is a track number register,
Reference numeral 18 denotes a current block number register, 19 denotes a current file number register, 21 denotes a table memory, and 22 denotes a RAM.

Claims (1)

(57) [Claims] 1. A magnetic head is provided for each track at a start end position or an end position of the magnetic tape so as to record or reproduce data blocks sequentially over a plurality of data tracks provided along the width direction of the magnetic tape. In a magnetic tape device that relatively moves in the width direction of a magnetic tape to position a desired data track, and records or reproduces data on the data track in block units, A storage unit for storing a block number or a file number, and upon receiving a block positioning command, the size of the block number or the file number of the last block of each data track and the block number or the file number of the block to be positioned, Data that contains the block to be positioned A recognition unit for recognizing a rack; and a head for moving the magnetic head from a position where it was positioned when the execution of the block positioning command is started in a width direction of the magnetic tape and positioning the magnetic head on the recognized data track. A magnetic tape device comprising: a drive unit; and a tape drive unit that moves the magnetic tape after the magnetic head is positioned on the recognized data track and positions the magnetic tape on the block to be positioned.