JP2844960B2 - Digital data recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital data recording / reproducing apparatus using a magnetic tape as a recording medium for an external storage device of a computer.

[0002]

2. Description of the Related Art In recent years, the capacity of digital data recording devices using magnetic tapes has been increasing for backup use of hard disks and the like. In these devices, as the backup capacity increases, the capacity of a built-in buffer memory is increased to reduce the occupation time of the host computer, and an error correction code is employed to improve the reliability of data to be recorded and reproduced. It has become

A conventional digital data recording / reproducing apparatus will be described below. FIG. 17 is a block diagram of this conventional digital data recording / reproducing apparatus. 17, an interface control unit 101 includes a start address memory 102 and an end address memory 103, and a control unit that controls data transfer between a host computer and a buffer memory 104. A data group processing unit 105 includes a data group memory 106. Error correction code processing unit with a work area,
The magnetic recording / reproducing unit 107 is a device for directly controlling recording / reproduction on a magnetic tape as a recording medium.

The operation of the digital data recording / reproducing apparatus includes a recording operation and a reproducing operation. First, the recording operation will be described.

[0005] The host computer issues a recording operation command to the digital data recording / reproducing apparatus using a record, which is a data block having a fixed capacity set in advance, as a unit for specifying the recording capacity. Upon receiving the recording operation instruction command, the interface control unit 101
Starts data transfer control for the specified number of records. The data transfer control method executed by the interface control unit 101 is a ring buffer method using the buffer memory 104. The interface control unit 101 stores the data received from the host computer at the position of the buffer memory 104 indicated by the start address unless the start address stored in the start address memory 102 matches the end address stored in the end address memory 103. Is incremented. When the start address matches the end address, the interface control unit 101 holds the received data, does not proceed to the next data reception, and does not write the data in the buffer memory 104. When the end address moves due to the data transfer from the buffer memory 104 to the data group memory 106 and does not match the start address, the interface control unit 101 writes the received data again at the position indicated by the start address, and sends the received data from the host computer. Resumes data reception.

On the other hand, when the data group processing unit 105 receives an operation instruction from the host computer via the interface control unit 101, the data control unit 105 sends the data group memory 106 from the buffer memory 104 to the interface control unit 101.
Request for data transfer to a magnetic tape, and start a process of generating a data group, which is the minimum unit for recording and reproduction on the magnetic tape. FIG. 3 is a structural diagram showing a logical structure of a data group generated on the data group memory 106. In FIG. 3, the data group has a logical two-dimensional array, and the direction of the arrow C matches the direction of the physical address of the data group memory 106. The interface control unit 101 records the record from the buffer memory 104 in the column direction of the two-dimensional array,
That is, the logical addresses in the two-dimensional array are transferred while being converted into physical addresses in the direction of arrow A, and are stored. When the transfer of the record included in the data group being processed is completed, the data group processing unit 105 sets the record as an information word,
An error correction code encoding process with the arrow A as the encoding direction is executed, the generated code parity is stored in the area shown in FIG. 3B, and the data group is completed on the data group memory 106. Data Group Processing The data group 105 is completed when the data group is completed.
At the same time, an operation instruction is issued to the data group 07 and the data is transferred from the data group memory 106 to the magnetic recording / reproducing unit 107 in the row direction of the two-dimensional array of the data group, that is, in the direction indicated by the arrow C in FIG. The magnetic recording / reproducing unit 107 records the transferred data on a magnetic tape, which is a recording medium, to execute magnetic recording with a data group as a minimum unit. FIG. 2 is a state diagram showing the state of a data group recorded on a magnetic tape. By interleaving the direction of the error correction code and the recording direction on the magnetic tape orthogonally as shown by arrows A and C in FIG. 3, one code sequence is scattered on the magnetic tape as shown by D. Become
The effect of a data error caused by damage to the magnetic tape or the like is minimized.

Next, the reproducing operation will be described. When the interface control unit 101 receives the command of the reproducing operation instruction from the host computer, it transmits the command to the data group processing unit 105. The data group processing unit 105 specifies the data group including the record specified by the command, and 107 is instructed to reproduce the data group. The magnetic recording / reproducing unit 107 searches the specified data group on the magnetic tape, starts a reproducing operation, and transfers the reproduced data to the group data processing unit 105. The group data processing unit 105 stores the transferred and transferred data on the logical two-dimensional array of the data group memory 106 shown in FIG. The data group processing unit 105 finishes the reproduction of the specified data group, and stores the two-dimensional array of FIG.
When completed on step 6, the data error generated during the reproducing operation is corrected by the decoding process of the error correction code multiplied in the direction of arrow A. When the error correction is completed, the data group processing unit 105 calculates the position of the record specified by the host computer on the two-dimensional array of the data group, and sorts the records in the order indicated by the arrow A in the interface control unit 101.
Request transfer to The data transfer control method executed by the interface control unit 101 in the reproducing operation is also a ring buffer method using the buffer memory 104 as in the case of the recording operation. The interface control unit 101 stores the data transferred from the data group processing unit 105 at the position of the buffer memory 104 indicated by the start address unless the start address stored in the start address memory 102 matches the end address stored in the end address memory 103. And the start address is incremented. On the other hand, the interface control unit 101 requests the host computer to receive data. When the host computer is ready to receive data, the interface control unit 101 transfers the data temporarily stored in the buffer memory 104 according to the receivable transfer speed of the host computer. End address memory 103 according to
Is moved to the end address stored in. If the host computer delays preparation for reception and the start address matches the end address, the interface control unit 101 does not proceed with data transfer from the data group processing unit 105 and does not write the data into the buffer memory 104. In this case, when the data transfer from the buffer memory 104 to the host computer is restarted, the end address moves, and when the end address does not match, the data reception from the data group processing unit 105 is restarted again.
Write the received data to the position indicated by the start address.

As described above, in the conventional recording operation and reproducing operation, while the data group processing for securing high data reliability by adding an error correction code and interleaving is adopted, the buffer memory 104 is executed in parallel with the processing. Since the data transfer control with the host computer is performed by using the buffer, the influence of the recording speed of the magnetic recording / reproducing unit 107 and the processing time of the data group processing unit 105 is minimized by using the buffer memory 104 as a large-capacity memory. This realizes high-speed transfer that minimizes the binding time required for data transfer by the host computer.

[0009]

However, in the above-mentioned conventional configuration, the data group has a logical two-dimensional array, whereas the interface control unit 1 executes the transfer control of the ring buffer system, so that the buffer memory 104 is used.
And the need for two large-capacity memories of the data group memory 106 and the record specified by the host computer being buffered when a reproducing operation is requested again after executing some recording and reproducing operations. Memory 4
The interface control unit 101 cannot obtain the storage address of the record even if the record is temporarily stored, and must reproduce the record from the magnetic tape again, resulting in a slow response. .

In a continuous recording operation of large-capacity data such as a backup process of a hard disk, if data transfer from a host computer is lower than a data recording speed on a magnetic tape, a two-dimensional array of data groups is not completed unless a magnetic tape is completed. Since the recording operation on the magnetic tape cannot be started, the recording operation on the magnetic tape is an intermittent operation in which recording and stop are repeated as needed, but the magnetic recording / reproducing unit 7 generally starts the actual data writing from the start of the recording operation on the magnetic tape. By this time, a long time is required for the search operation, the tracking pull-in control, and the like, so that there has been a problem that the backup processing time is greatly increased overall in comparison with the data transfer time from the host computer.

The present invention solves the above-mentioned conventional problems, and realizes data group processing and transfer control processing with one buffer memory, and temporarily stores data specified by a host computer in the buffer memory. The object of the present invention is to provide a digital data recording / reproducing device which responds at high speed when the data transfer speed of the host computer is lower than the data recording speed on the magnetic tape, and does not increase the overall processing time. I do.

[0012]

In order to achieve this object, a digital data recording / reproducing apparatus according to the present invention comprises: a magnetic tape recording / reproducing means for recording / reproducing a data group on a magnetic tape in a minimum unit; A buffer memory for temporarily storing one data group in one area after being divided into areas, a control information memory for storing control information indicating a processing state of the temporarily stored data group, and a temporarily stored data group. An identification information memory for storing identification information to be distinguished, and an interface for referring to the identification information and the control information, giving an operation start instruction to the magnetic tape recording / reproducing means according to the state, and controlling transfer of a record specified to the host computer When the control unit, referring to the identification information and the control information and executing the data group management process according to the state, A reproducing operation control unit for giving a reproduction operation stop instruction to the magnetic tape recording / reproducing unit; and a data group management process and a protection process are executed by referring to the identification information and the control information and according to the state thereof, and It has a configuration provided with recording operation control means for giving a recording operation end instruction to the reproducing means.

[0013]

According to the present invention, the buffer memory having a plurality of regions having a logical two-dimensional array configuration manages the processing state of each region by the control information corresponding to each region on a one-to-one basis. Buffering can be performed in units, and a memory for buffering and a memory for work in group processing can be shared and operated with one buffer memory.

In addition, whether the operation is a recording operation or a reproducing operation,
In the data group area temporarily stored in each area of the buffer memory, identification information corresponding to each area in a one-to-one correspondence is uniquely managed, so that a record requested by the host computer is always stored in the buffer memory. Immediately determine if it is stored, and if so, its location.
Calculation and transfer can be started, realizing a high-speed response.

In a continuous recording operation of large-capacity data such as a backup process of a hard disk, if the data transfer from the host computer is lower than the data recording speed on the magnetic tape, the recording operation processing means executes a protection process, and all the data are transferred to zero. By recording a special data group composed of the above data on the magnetic tape recording / reproducing means to secure the transfer time for completing the data transfer from the host computer, it is necessary to perform an intermittent operation for interrupting the recording operation on the magnetic tape. Instead, the continuous recording operation is completed in the shortest processing time overall.

[0016]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a digital data recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, a buffer memory 1 is a random access memory 2 (hereinafter referred to as a RAM).
2), a logical address converter 3 for converting a virtual logical address and a physical address of the RAM 2, and a logical bus 4 a and a logical bus 4 b. A memory device that can be accessed by being divided into a dimensional space; an interface control unit 5 is connected to the buffer memory 1 via a logical bus 4a and is connected to a host computer as an external device; The processing unit 6 is connected to the buffer memory 1 via the logical bus 4a, and is a code processing unit that executes an error correction code encoding process and an error correction process on the data stored in the buffer memory 1. The magnetic recording / reproducing unit 7 is a device for directly recording / reproducing digital data using a magnetic tape as a recording medium. The recording operation control unit 8 and the reproduction operation control unit 9 are both connected to the buffer memory 1 via the physical bus 4b.
The recording operation control unit 8 outputs recording data to the magnetic recording control unit 7 via the digital transmission circuit 10, and the reproduction operation control unit 9 is a control unit that inputs reproduction data from the magnetic recording / reproduction unit 7. The control information memory 11 and the identification information memory 12
These are memories for storing the same number of control information and identification information as the number of virtual two-dimensional spaces in the buffer memory 1, respectively, which are referred to by the interface control unit 5, the recording operation control unit 8, and the reproduction operation control unit 9, Connected writable. The magnetic tape operation flag register 13 is connected to the recording operation control unit 8 and the reproduction operation control unit 9 so as to be referred to and writable. The continuous ampule counter 14 is a counter connected to the recording operation control unit 8.

With respect to the digital data recording / reproducing apparatus, a description will first be made of a data recording form on a magnetic tape as a recording medium and a data storage form on a buffer memory 1, and then a recording operation and a protection in the recording operation will be described. The processing and the reproducing operation will be sequentially described.

First, a recording form on a magnetic tape will be described with reference to FIGS. FIG. 2 is a state diagram showing a magnetic tape Ueno recording mode. In FIG. 2, a data group, which is a block of fixed-capacity data, is continuously formed on a magnetic tape, and the inside of the data group is constituted by a plurality of continuous tracks formed by a helical scan method. . Each data group is sequentially numbered with a group number as information for identifying the data group from other data groups.
Operates with the data group as the minimum delimiter for recording / reproducing, and performs recording / reproducing operation on the data group specified by the group number. FIG. 3 is a logical structure diagram showing a logical structure of data recorded and reproduced in the data group of FIG. In FIG. 3, the data group has a virtual two-dimensional array structure, and includes a plurality of fixed-capacity records transmitted and received from the host computer and a parity part of an error correction code configured in the direction indicated by arrow A, that is, the column direction. In. An example of the error correction code is configured as one code sequence. Since this two-dimensional array is recorded and reproduced on the magnetic tape in the direction indicated by arrow C, that is, in the row direction, one error correction code sequence is dispersed on the magnetic tape as indicated by arrow D in FIG. Interleaving is realized, and has a high error correction capability with respect to a data error caused by a loss of a magnetic tape or the like.

In the following description, the two-dimensional array shown in FIG. 3 has 38 rows and 4096 columns, the 0th to 31st rows are record areas, and the 32nd to 37th rows are parity areas. It is also assumed that the record capacity is fixed to 512 bytes, that is, 16 columns per record, and the logical address of the first record included in a certain group in the virtual two-dimensional space is defined as the 0th row and the 0th column. FIG. 4 shows the buffer memory 1
8 is a memory map showing a data storage format of the memory. When the buffer memory 1 is accessed from the logical bus 4a, FIG.
Each page has the same structure as the virtual two-dimensional array of the data groups shown in FIG. 3, and one page temporarily stores one data group. When the page number is P and the logical address of the virtual two-dimensional array is the Nth row and the Mth column, the logical address converter 3 converts the logical address to the corresponding physical address Adr by Adr = P
* 4096 * 38 + M * 38 + N
Access AM2. In FIG. 4, the identification information memory 12 has the same number as the total number of pages, and is a memory for storing identification information corresponding to each page on a one-to-one basis, or a group number of a data group temporarily stored in each page as identification information. Remember. Similarly, the control information memory 11 is a memory that corresponds to each page one-to-one and stores control information indicating the processing state of the data group temporarily stored in each page. In this embodiment, the total number of pages is six pages from the 0th page to the 5th page.

Next, the recording operation will be described. It is assumed that the recording operation of this embodiment is sequentially accessed from the host computer. FIGS. 5, 6, and 7 show the interface control unit 5 in the recording operation of this embodiment.
7 is a flowchart showing a processing procedure of a recording operation control unit 8 and a code processing unit 6. The host computer issues a recording operation instruction command to the digital data recording / reproducing device with a fixed large amount of records as a unit for designating a recording position and a recording amount. First, when the interface control unit 1 receives the command of the recording operation instruction, the interface control unit 1 executes step 50 in FIG.
In step 1, the group number of the data group including the target record to be processed specified by the host computer and the logical address of the target record in the group are calculated. By checking the group number, it is determined whether or not the corresponding data group is temporarily stored in the buffer memory 1. If the data group is stored, the page number is obtained, and the process proceeds to step 503. An integer value 7 is written in the control information of the page number to be written, and the data of the record to be recorded from the host computer via the logical bus 4a is written to the address on the virtual two-dimensional array indicated by the page number and the logical address of the target record. Transfer. (Table 1) shows the definition of the control information. In the case of the recording operation, the control information defines an integer value from 7 to 4, and the value decreases as the processing state of the corresponding page in the buffer memory 1 progresses. In the case of the reproducing operation, the integer value 1 to the integer value 4 are defined so as to increase as the processing state progresses, and the integer value 0 indicates that the buffer memory 1 is not used immediately after the power is turned on. Defined for use.

[0022]

[Table 1]

When the data transfer from the host computer is completed, the interface control unit 5 proceeds to step 50 in FIG.
In step 4, it is determined whether or not the record that has just been transferred is the last record of the records constituting the corresponding data group.
If the record is the last record, the control information of the corresponding data group is stored with an integer value 6 indicating the completion of data transfer from the host computer in step 505, and then the process proceeds to step 506. It is determined whether or not all the records have been transferred to the buffer memory 1. If all the transfers have been completed, the process is terminated and the next command is awaited.
Returning to 01, the transfer processing of the transfer record is continued.

On the other hand, the code processing section 6 executes the coding processing of the error correction code of the data group shown in FIG. 7 in parallel with the processing of the interface control section 5 described above. In step 701 of FIG. 7, the code processing unit 6 checks all control information in the control information memory 11, and determines whether the control information is an integer 6, that is, whether a group in which coding processing can be started is temporarily stored in the buffer memory 1. Repeat inspection. When the interface control unit 5 writes the integer value 6 in the control information in step 505, the code processing unit 6 finds the integer value 6, obtains the page number of the buffer memory 1 corresponding to the control information, and proceeds to step 702. To go to the logical bus 4a for the data group stored in the corresponding page of the buffer memory 1.
The encoding process of the error correction code is started as shown in FIG. 3 via the, and the generated parity is transferred to the area B in FIG. When the encoding process is completed, the encoding processing unit 6 proceeds to step 7
In step 03, an integer value 5 indicating the completion of the encoding process is stored in the control information of the page for which the encoding process has been completed.
Returning to 01, the search for the data group that can be encoded is restarted.

If the interface control unit 5 detects in step 502 that the data group including the target record is not temporarily stored in the buffer memory 1, it proceeds to step 507 to delete all the control information stored in the control information memory 11. Is searched for a page that can be reused as an integer value 4 or less, that is, a page for temporary storage of a new data group. If there is a reusable page, the page number is obtained, the group number corresponding to the identification information corresponding to the page number is stored in step 508, and a series of processes from step 503 onward are executed. The data transfer from the host computer is executed to one new page. For example, when the host computer instructs the storage operation of 2048 records from the position corresponding to the first record of the data group of group number 9 when the buffer memory 1 is in the state of FIG. The control information is set to an integer value of 7, data transfer is performed for the first 256 records, and the control information is advanced to an integer value of 6. The next record to be transferred is to be stored in the group number 10, but since there is no page in the buffer memory 1 in which the group number 10 is temporarily stored, one page is selected from the reusable pages in the process of step 507. Here, assuming that page 0 is selected, the interface control unit writes the group number 10 in the identification information of page 0 and the integer value 7 in the control information, causes the host computer to transfer 256 records, and adjusts the transfer end control information. Proceed to Numerical Value 6. Hereinafter, the second page, the third page and the transfer buffer are sequentially used. As described above, as the transfer of the record from the host computer is buffered in the buffer memory 1 by the processing of the interface processing unit 5 shown in FIG. The number of data groups processed further than the completion of transfer from the computer increases. Now, all of the six pages in the buffer memory 1 are equal to or greater than the transfer completion from the host computer, that is, the integer value 6 or the integer value 5
Let's say you went to At this time, the interface control unit 5 determines in step 507 of FIG.
If it is determined that the magnetic tape can be temporarily stored, and the magnetic tape operation flag register 13 is referred to in step 509 and it is detected that the recording operation on the magnetic tape has not been started, the recording operation control unit 8, a recording operation start request is issued, and the process returns to step 507. If the recording operation is already being performed on the magnetic tape, the process returns to step 507, and the magnetic recording / reproducing unit 7 and the recording operation control unit 8
The process waits until any page on the buffer memory 1 becomes reusable.

When the recording operation control section 8 receives the recording operation start request, the recording operation control section 8 refers to the control information of the first data group in which the recording operation is to be started in step 601 in FIG. Wait for the processing to be completed, and when completed, set the magnetic tape operation flag register 13 in step 602 and instruct the magnetic recording / reproducing unit 7 to start the recording operation. The magnetic recording / reproducing unit 7 moves the magnetic tape to the position of the data group where the recording operation starts, and starts recording on the magnetic tape with the recording data given from the recording operation control unit 8. At the start of magnetic recording, the recording operation control unit 8 clears the continuous amble count 14 in step 603, and in step 604 records from the corresponding page of the buffer memory 1 via the physical bus 4b in the direction of arrow C in FIG. The data is transferred to the magnetic recording / reproducing unit 7. When the transfer for one group is completed, the recording operation control unit 8 writes the integer value 4 indicating the completion of the recording operation to the control information of the page that has been transferred to the magnetic recording / reproducing unit 7 in step 605, and continues the magnetic processing in step 606. It is checked whether the control information of the data group to be continuously transferred to the recording / reproducing unit 7 indicates that the encoding has been completed, and if the encoding has been completed, the recording data transfer processing after step 603 is continued.

On the other hand, the interface control unit 5 detects in step 507 that the recording operation control unit 8 has written the integer value 4 in the control information in step 605, and reuses the page to rewrite the buffer memory 1 of the next record. Start transfer to. FIG. 8 is an example showing the state of the buffer memory 1 after the start of the recording operation on the magnetic tape. The data group of group number 10 on page 0 is in a reusable state upon completion of recording on the magnetic tape, and the group number 1 on page 2 is
The third and fourth data groups are being recorded on the magnetic tape.
The group numbers 12 and 13 of the pages are in a state of waiting for the start of recording on the magnetic tape after the completion of the encoding process, the group number 14 of the fifth page is in the encoding process, and the first page is the magnetic tape whose group number is 9 in FIG. In FIG. 8, the data is re-used in the buffer of the group number 15 and the data is being transferred from the host computer.

As described above, the data transfer process from the host computer shown in FIG. 5 to the buffer memory 1 by the interface control unit 5, the coding process shown in FIG. Buffer memory 1 shown in 6
The data transfer process from the CPU to the magnetic recording / reproducing unit 7 performs the processes in parallel with each other on the plurality of pages of the buffer memory 1 using the control information and the identification information of each page as clues, thereby hosting each page. Since the buffer memory for transfer control from the computer and the work memory for data group processing can be used in common, there is no need to have two buffer memories independently, and a recording operation in units of pages in one buffer memory 1 Buffering is efficiently realized.

Next, the operation of the protection processing in the recording operation will be described. In the above-described buffering of the recording operation, when the transfer speed of the host computer is higher than the recording speed of the magnetic recording / reproducing unit 7, the difference in the speed is effectively absorbed. On the other hand, when the transfer speed of the host computer is low or the transfer of the host computer is temporarily interrupted, a protection process for minimizing an increase in the time required for recording is required. Hereinafter, this protection processing will be described.

When the transfer speed of the host computer is low or the transfer is temporarily interrupted, the code in the buffer memory 1 is repeated by repeating the recording control processing on the magnetic tape from step 602 to step 606 of the recording operation control unit 8. The number of encoded pages decreases, and eventually, the data group to be continuously recorded by the magnetic recording / reproducing unit 7 reaches a state in which encoding is not completed. When the recording operation control unit 8 detects this in step 606, the recording operation control unit 8 forms an amble group, which is a special temporary data group in which the recording data is all zeros, on the magnetic tape to thereby determine the data group to be originally recorded. The protection processing for creating the transfer and encoding processing time is started. First, step 60
In step 7, if it is detected by referring to the continuous amble counter 14 that the value is equal to or smaller than a preset limit value, the process proceeds to step 608, and the disconnection signal of the digital transmission circuit 10 is output as true. When true is output to the disconnection signal, the digital transmission circuit 10 generates zero data of a capacity corresponding to one data group by hardware and transfers it to the magnetic recording / reproducing unit 7. The magnetic recording / reproducing unit transmits the zero data to a magnetic tape. By recording above, an amble group is formed. On the other hand, the recording operation control unit 8 checks all the identification information in the identification information memory 12 in step 609, and assigns 1 to all data groups having a group number equal to or greater than the group number of the amble group being recorded. In step 610, the continuous amble count 14 is incremented. When the zero data transfer of the digital transmission circuit 10 is completed, the recording operation control section 8 proceeds to step 61.
In step 1, false is output to the disconnection signal, and the process returns to step 606. The processing of the interface control unit 5 and the code processing unit 6 proceeds according to the recording time during which the amble group is formed on the magnetic tape, and the data group for which the magnetic recording / reproducing unit 7 is to continue recording is completed. If so, the recording operation control unit 8 proceeds to step 603 to start the recording data transfer process, and if the encoding is not completed, the recording operation control unit 8 proceeds to step 6.
If the process proceeds to 07, the protection process is executed again. FIG. 9 shows a state of the magnetic tape in which the protection processing is executed twice consecutively and two amble groups are formed. In FIG. 9, group numbers 15 and 16 are amble groups. In the data group of the group number 17, since the completion of the encoding was not in time for the start of the transfer of the recording data to the magnetic recording / reproducing unit 7, the data to be recorded as the group number 15 is shifted to the group number 17 and recorded. FIG. 10 shows the state of the buffer memory 1 when the amble group of the group number 16 in FIG. 9 is being recorded. FIG.
At 0, the data group of the group number 17 of the first page was the group number 15 in FIG. 8, but the recording process is not started on the magnetic tape because the encoding process is being performed, and the group number is shifted by the protection process. ing.

As described above, even when data transfer from the host computer is delayed due to the protection processing of the recording operation control unit 8, the recording operation on the magnetic tape can be performed without stopping the recording operation on the magnetic tape by temporarily recording the amble group. And the processing time of the code processing unit 6 can be created. Generally, once the recording operation is stopped, the magnetic recording / reproducing unit 7 must search and move the recording position on the tape based on the group number when resuming the recording operation next, and further until the tracking is stabilized. , It takes a lot of time until the recording time. However, by forming an amble group by the protection processing of Steps 607 to 611 of the recording operation control unit 8, data transfer from the host computer and improper operation can be performed without inadvertently interrupting the recording operation of the recording / reproduction control unit 7. Since the recording can be started immediately on the magnetic tape when the processing is completed, the recording operation is completed almost in the data transfer time from the host computer, and the increase in the time required for recording can be minimized. You can do it. Moreover, as shown in FIG. 10, a dedicated buffer for the amble group is not required, so that high utilization efficiency of the buffer memory 1 can be ensured.

When the recording operation control unit 8 detects in the protection processing that the value of the continuous amble count 14 has reached the preset limit value in step 607 of FIG. 6, data transfer from the host computer is temporarily interrupted. It is determined that the recording has been performed, and the process proceeds to step 12 to issue a recording operation stop instruction to the magnetic recording / reproducing unit 7, reset the magnetic tape operation flag register 13, and end the series of recording operation control processing of FIG. Upon receiving the recording operation stop instruction, the magnetic recording / reproducing unit 7 ends the recording operation on the magnetic tape. Even after the recording operation control unit 8 finishes the recording operation control process, the interface control unit 5 continues the interface control process of FIG. 5, the data transfer from the host computer is resumed, and the data transfer from the host computer to the buffer memory 1 is completed. When the data group is accumulated, the recording operation control unit 8 is requested to restart the recording operation in the processing of steps 507, 509, and 510 again. That is, when the data transfer from the host computer is interrupted for a long time, the recording operation of the magnetic recording / reproducing unit 7 is stopped, so that there is a danger that a large capacity area on the magnetic tape is consumed as an amble group. Can be prevented. Also, when the data transfer from the host computer is restarted, the recording operation on the magnetic tape is automatically restarted as necessary, so that the host computer does not require any special processing to interrupt the data transfer, It is extremely versatile.

Next, the reproducing operation will be described. In the reproducing operation of the present embodiment, it is assumed that sequential access is made from the host computer as in the recording operation. FIGS. 11, 12, and 13 are flowcharts showing the processing procedure of the interface control unit 5, the reproduction operation control unit 9, and the code processing unit 6 in the reproduction operation of this embodiment. The host computer issues a reproduction operation instruction command to the digital data recording / reproducing apparatus according to the present embodiment, using the record as a specified unit of a reproduction position and a reproduction amount. First, when the interface control unit 1 receives the command of the reproduction operation instruction, the interface control unit 1 calculates the group number of the data group including the target record specified by the host computer in step 1101 of FIG. 11 and stores it in the identification information memory 12 in step 1102. It is determined whether the corresponding data group is temporarily stored in the buffer memory by inspecting the group number that has been set. If not, it is determined in step 1103 that the magnetic tape operation flag register 1
When it is confirmed that the reproducing operation for the magnetic tape has not been started with reference to Step 3, a reproducing operation start request is issued to the reproducing operation control unit 9 in Step 1104, and Step 110 is performed.
Return to 2. If the reproducing operation from the magnetic tape has already been started, the process returns to step 1102, and the processing of the magnetic recording / reproducing unit 7 and the reproducing operation control unit 9 proceeds to transfer the corresponding data group to the buffer memory 1. Will wait for

When the reproduction operation control unit 9 receives the reproduction operation start request, it checks all the control information in the control information storage memory 11 in step 1201 in FIG. Since it can be used as a buffer for temporarily storing the reproduction data from the reproduction unit 7, the value is changed to an integer value 4. Next, in step 1202, all control information is checked again, and a page to be used as a buffer first is determined from pages whose value is the integer value 4.
Next, proceeding to step 1203, the group number of the data group to be reproduced is stored in the identification information corresponding to the determined page, and in step 1204, the integer corresponding to the start of the reproducing operation is stored in the corresponding control information. At 1205, the magnetic tape operation flag register 13 is set, and the magnetic recording / reproducing section 7 is instructed to start the reproducing operation. After moving the magnetic tape to the position where the reproducing operation starts, the magnetic recording / reproducing unit 7 starts the reproducing operation and starts transferring the reproduction data to the reproducing operation control unit 9. In step 1206, the reproducing operation control unit 9 transfers the reproduced data transferred from the magnetic recording / reproducing unit 7 to the corresponding page of the buffer memory 1 via the physical bus 4b in the direction of arrow C in FIG. I will store it temporarily. When the transfer for one group is completed, the reproduction operation control unit 9 proceeds to step 120.
7, the control information of the page to which the transfer of the reproduction data has been completed from the magnetic recording / reproduction unit 7 has an integer value 2 indicating the completion of the reproduction operation.
Then, in step 1202, the process returns to the process of determining the page of the buffer memory 1 for temporarily storing the reproduced data of the data group to be continuously reproduced by the magnetic recording / reproducing unit 7. Subsequently, the data groups to be continuously reproduced by the magnetic recording / reproducing unit 7 are temporarily stored in the buffer memory 1 in order.

On the other hand, the code processing section 6 executes the error correction processing of the reproduced data group shown in FIG. 13 in parallel with the processing of the reproduction operation control section 9 described above. In the reproducing operation, the code processing unit 6 checks all control information in the control information storage memory 11 at step 1301 in FIG. Repeated inspections are temporarily stored above. When the reproducing operation control unit 9 stores the integer value 2 in the control information in step 1207, the code processing unit 6 finds out the integer value 2 and obtains the page number of the buffer memory 1 corresponding to the control information, and obtains the step 1302 To perform error correction processing on the data group of the corresponding page via the logical bus 4a using the parity of the error correction code configured as shown in FIG. correct. When the error correction processing is completed, the code processing unit 6 stores the integer value 3 indicating the completion of the error correction processing in the control information of the page for which the processing has been completed in step 1303, returns to step 1301, and returns to the data group in which the error correction processing is possible. Resume search for.

The group number stored in the identification information storage memory by the reproduction operation control section 9 in step 1203 is the data group including the target record in the identification information check in step 1102 of the interface control section 5.
Then, the interface control unit 5 obtains the page number and proceeds to step 1105 to check the corresponding control information and transfer the target record to the host computer. Determine if it is in a state. According to the definition of the control information in Table 1, if the control information is a value between integers 3 and 7 in the case of a reproducing operation, the target record is transferred from the host computer or reproduced from the magnetic tape and subjected to error correction processing. Is completed, and is temporarily stored in the buffer memory 1 without any error. Therefore, the interface control unit 5 determines that the transfer is possible when the control information has the integer value 3 or more. Next, in step 1106, the logical address of the target record in the corresponding data group is calculated. In step 1107, the logical bus 1a is assigned to the address on the virtual two-dimensional array indicated by the page number and the logical address of the target record. The data of the designated record is transferred to the host computer via the host computer. When the data transfer to the host computer is completed, the interface control unit 5 determines in step 1108 whether or not the record that has just been transferred is the last record included in the corresponding group. In the following, that is, in the case of a page used as a buffer for the reproducing operation, in step 1109, the corresponding control information is stored with an integer value 4 indicating that the data group is a data transfer completed group to the host computer in the corresponding data group. Next, in step 1110, it is determined whether or not all the records requested to be reproduced by the command from the host computer have been transferred to the host computer. If the transfer of all records has been completed, the process ends once and the next command is waited. If any untransferred records remain, the process returns to step 1101 to continue the transfer processing of the untransferred records. FIG.
FIG. 4 shows an example of the state of the buffer memory 1 when the reproduction operation is being continued. In FIG. 14, the group number 12 of the 0th page is a buffer storing the reproduction data from the magnetic recording / reproducing unit 7, the group number 11 of the 5th page is in error correction processing, and the group number of the 3rd and 4th pages. 9 and 10 indicate the completion of the error correction processing, and the group numbers 7 and 8 of the first and second pages have also completed the data transfer to the host computer and are in a reusable state as a buffer for the reproducing operation. The interface controller 5 is transferring data of the third page to the host computer. When the transfer is completed, the interface controller 5 sets the control information of the third page to the integer value 4, and continues the fourth page.
Start transferring the page. When the reproduction data transfer from the magnetic recording / reproduction unit 7 to the 0th page is completed, the reproduction operation control unit 9 advances the control information to an integer value of 2 and continues to use the first page as a reproduction buffer of the group number 13. use.

As described above, the data transfer process from the buffer memory 1 shown in FIG. 11 to the host computer by the interface control unit 5, the error correction process shown in FIG. The process of transferring data from the magnetic recording / reproducing unit 7 to the buffer memory 1 shown in FIG. 12 is performed in parallel with respect to a plurality of pages of the buffer memory 1 using the control information and identification information of each page as clues. As in the case of the recording operation, the buffer memory with good transfer control from the host computer and the working memory for data group processing can be shared, so that it is not necessary to have two independent buffer memories and one buffer memory 1 efficiently realizes buffering of the recording operation in units of pages. Further, if the data group already temporarily stored in the buffer memory 1 includes the target record specified by the host computer, the transfer operation is started immediately without starting the reproducing operation from the magnetic tape. Also produces the effect as a cache memory,
This realizes high-speed operation.

In the above operation, when the transfer speed of the host computer is higher than the reproduction speed of the magnetic recording / reproducing unit 7, the buffering operation absorbs the speed difference. Next, the operation when the transfer speed of the host computer is low or the transfer of the host computer is temporarily interrupted will be described. In this case, the reproduction operation control unit 9
By repeating the temporary storage processing of the reproduced data in the buffer memory 1 in steps 1202 to 1207, the number of error correction processing completed pages in the buffer memory 1 increases, and the data group to be reproduced next is temporarily stored. There is no page that can be reached. When this time is detected in step 1202, the reproduction operation control unit 9 determines that the data transfer from the host computer has been temporarily interrupted, and
In step 8, the reproduction operation stop instruction is issued to the magnetic recording / reproduction unit 7, the magnetic tape operation flag register 13 is reset, and the series of reproduction operation control processing of FIG. Upon receiving the reproduction operation stop instruction, the magnetic recording / reproduction unit 7 ends the reproduction operation from the magnetic tape. Since the interface control unit 5 continues the interface control process of FIG. 1 even after the reproduction operation control unit 9 ends the reproduction operation control process, when the data reception of the host computer is resumed, steps 1101, 1102, and 1105 are performed. Step 111
The process of 0 proceeds, and the number of data groups reproduced from the magnetic tape stored in the buffer memory 1 decreases.
Eventually, when the data group including the record specified by the host computer no longer exists in the buffer memory, the processing in steps 1103 and 1104 again requests the reproduction operation control unit 9 to resume the reproduction operation. In other words, when the data transfer from the host computer is interrupted for a long time, the reproducing operation of the magnetic recording / reproducing unit 7 is stopped. The reproduction operation from the server can be resumed, and no special processing is required of the host computer even after the data transfer is interrupted. It is highly versatile.

Next, the definition of the control information shown in (Table 1)
Step 507 in FIG. 5, step 1105 in FIG.
2. The relationship between the judgment processing such as step 1202 of No. 2 and the state of each page on the buffer memory 1 will be described, and the buffer memory 1 will be used efficiently without any problem in buffering in these judgments. Is shown.

Now, it is assumed that the recording operation instructed by the host computer has been completed, and the buffer memory 1 at that time is terminated.
Are in the state shown in FIG. At this time, the control information indicates that the data group of the group number 15 temporarily stored in the 0th page has been completed up to the encoding process but has not yet been recorded on the magnetic tape, and the data group of the group number 16 on the first page has Indicates that there is room for storing records from the host computer and the data is not recorded on the magnetic tape, but the data groups stored on other pages have already been recorded on the magnetic tape. In this state, when the host computer instructs the recording operation again, the interface control unit 5 starts the transfer from the record transfer to the spare portion of the group number 16 data group. At step 505, the control information is rewritten from 7 to 6, and a page to be used as a buffer is selected at step 507. In the process of step 507, if the control information is 4 or less, the interface control unit 5 solders that it can be used as a new buffer, but in the example of FIG. 15, it is determined that four pages from the second page to the fifth page can be used. One of them is selected and the group number 17
Will be used as a buffer. That is, the 0th
The page storing the page and the first page of the unrecorded data group on the magnetic tape are not erroneously used as a new buffer, but are securely stored until the next recording operation on the magnetic tape is started. Things.

Next, a case where a reproducing operation is instructed from the host computer when the buffer memory 1 is in the state shown in FIG. 15 will be described. Interface control unit 5
Calculates the number of the data group including the specified target record in the process of step 1101, and the value is 15
, The 0th page is to be processed. If the control information is equal to or larger than the integer value 3 in step 1105, it is determined that transfer to the host computer is possible, and the target record is transferred from page 0 to the host computer. In this case, the record previously transferred from the host computer for recording and stored in the buffer memory 1 is transferred again to the host computer as it is. Further, since the control information is the integer value 5, the transfer is not completed at the end of the transfer in the judgment of step 1108, and therefore the integer value 5 is held without proceeding to step 1109. The stored contents of page 0 are retained until the next recording operation on the magnetic tape, and unrecorded pages are not inadvertently destroyed. Next, consider a case where the target record requested to be reproduced by the host computer is included in the data group of group number 5. In this case, since the data group is not stored in the buffer memory 1, the reproducing operation from the magnetic tape is started. In the processing of step 1202, the reproduction operation control unit 9 determines that the page whose control information is the integer value 4 can be used as a temporary storage buffer for the reproduction data from the magnetic recording / reproduction unit 7, but in the example of FIG. It is determined that four pages up to the fifth page are usable, and any one of them is used as a buffer for the data group of group number 5, but the zeroth page and the first page may be erroneously used as new buffers. Absent. Also in this case, the page storing the unrecorded data group on the magnetic tape is stored without being used.

Next, the operation from the completion of the reproducing operation will be described. Now, it is assumed that the reproduction operation instructed by the host computer has been completed, and the buffer memory 1 at that time has been completed.
Are in the state shown in FIG. At this time, the control information indicates that the data groups of the 0th page and the 1st page are not recorded on the magnetic tape, and the data groups of the other pages are reproduced from the magnetic tape. In this state, when a recording operation is next instructed from the host computer, the interface control unit 5 starts record transfer from the spare portion of the group number 16 data group. Is rewritten from 7 to 6, and a page to be used next as a buffer is selected in step 507. In the process of step 507, if the control information is 4 or less, the interface control unit 5 determines that it can be used as a new buffer. In the example of FIG. 16, however, it is determined that four pages from the second page to the fifth page can be used, and Either one is selected and used as the buffer of the group number 17, and the page storing the 0th page and the 1st page of the unrecorded data group on the magnetic tape is also stored.

Next, a case where a reproduction operation is instructed from the host computer when the buffer memory 1 is in the state shown in FIG. 16 will be described. The interface control unit 5 calculates the number of the data group including the specified target record in the process of step 1101. When the value is 15 or 16, the target record is immediately transferred from the buffer memory 1 to the host computer. However, after the transfer is completed, the unrecorded pages on the magnetic tape are stored in the same manner as in the case of the reproducing operation following the recording operation. When the target record requested to be reproduced by the host computer is included in the data group of the group number 5, 6, 7, or 8, the control information is set to the integer value 3
Therefore, the error correction processing is completed, and the transfer to the host computer is started as it is. When the target record is included in the data record of the group number 11, the reproduction operation from the magnetic tape is started because the data record is not stored in the buffer memory 1. The reproduction operation control unit 9 initializes the control information having the integer value of 3 or less to the integer value 4 in the process of step 1201, so that the second to fifth pages are initialized to the integer value 4.
Thereafter, in the process of step 1202, it is determined that the page whose control information is the integer value 4 can be used as a temporary storage buffer of the reproduction data from the magnetic recording / reproducing unit 7, so that any one of the four pages from the second page to the fifth page is used. Is used as a buffer for the data group of group number 11. Also in this case, the pages of the 0th page and the 1st page of the unrecorded data group on the magnetic tape are securely stored without being used erroneously.

As described above, according to the digital data recording / reproducing apparatus of the embodiment of the present invention, as shown in (Table 1), in the recording operation, the integer value decreasing in the progress of the processing in the recording operation, and the processing value in the reproducing operation, The same integer value is defined for the completion of the recording operation and the completion of the reproduction operation, respectively, so that whether the type of operation immediately before the recording operation or the reproduction operation is the recording operation or not is determined. Regardless of whether or not the page that should always be saved by the same judgment processing is correctly saved, and only the page that can be used as a new buffer will be used as a new buffer,
Reliable and efficient buffering is realized. In addition, since each determination process can accurately determine the control information by comparing the control information with a specific reference value, the process can be simply and easily realized, and the determination can be made in a short time.

In this embodiment, the interface control unit 5, the recording operation control unit 8, and the reproduction operation control unit 9 are independent control units. However, these units are replaced by a single microprocessor, and each processing is performed by multitasking. Alternatively, a configuration may be adopted in which an execution method corresponding thereto is adopted.

[0046]

As is apparent from the above embodiments, the digital data recording / reproducing apparatus of the present invention comprises a magnetic tape recording / reproducing means for recording / reproducing a data group as a minimum unit on a magnetic tape, and a plurality of logical areas. A buffer memory for temporarily storing one data group in one area, a control information memory for storing control information indicating a processing state of the temporarily stored data group, and a temporarily stored data group. An identification storage memory for storing identification information to be processed, and an interface for referring to the identification information and the control information to start and give an instruction to the magnetic tape recording / reproducing means in accordance with the state thereof, and to transfer a designated record to the host computer The control means, referring to the identification information and the control information, and executing the data group management process according to the state. Operation control means for instructing the magnetic tape recording / reproduction means to perform a reproduction operation, and executing the data group management processing and the protection processing according to the state with reference to the identification information and the control information. By providing a recording operation control means for giving a recording operation end instruction to the means, a buffer memory having a plurality of regions having a logical two-dimensional array configuration has a one-to-one correspondence between the processing state of each region and each region. Since the control information to be managed is managed, a buffer memory for each area can be provided, and the memory for buffering and the working memory for group processing can be shared and operated with one buffer memory.

In addition, whether it is a recording operation or a reproducing operation,
Since the identification information corresponding to each area of the data group identification temporarily stored in each area of the buffer memory has a one-to-one correspondence, a record requested by the host computer is stored in the buffer memory. If the data is stored, the storage position can be immediately determined, calculated, and the transfer can be started. Therefore, the effect as a cache memory can be generated in the buffer memory, and a high-speed response can be realized. is there.

Further, in the continuous recording operation of large-capacity data, when the data transfer from the host computer is lower than the data recording speed on the magnetic tape, the recording operation processing means executes the protection processing, and is composed of all zero data. By recording the special data group on the magnetic tape recording / reproducing means, a transfer time for completing the data transfer from the host computer is secured, so that there is no need to perform an intermittent operation for interrupting the recording operation on the magnetic tape. Even if the transfer with the oven toaster is interrupted due to the cause, the recording / reproducing operation on the magnetic tape is automatically stopped or restarted according to the interruption time, so continuous recording operation is realized with the shortest overall processing time be able to.

Moreover, since the control information is comprehensively defined by the recording operation and the reproducing operation, the page to be always stored by the same judgment processing in the recording operation and the reproducing operation is always correct regardless of the immediately preceding operation. Since the control for saving is executed, highly reliable and efficient buffering can be realized. These controls can be easily and accurately determined by comparing the control information with a specific reference value, so that the processing is simple and can be realized very easily.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a digital data recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a state diagram showing a recording state of a magnetic tape.

FIG. 3 is a logical structure diagram of a data group.

FIG. 4 is a memory map of a buffer memory 1 according to an embodiment of the present invention.

FIG. 5 is a flowchart of a process in a recording operation of the interface control unit 5 of the embodiment.

FIG. 6 is a flowchart of a process in a recording operation of a recording operation control unit 8 of the embodiment.

FIG. 7 is a flowchart of a process in a recording operation of the code processing unit 6 of the embodiment.

FIG. 8 is a memory map of the buffer memory 1 during a recording operation of the embodiment.

FIG. 9 is a state diagram showing the recording state of the magnetic tape after execution of the protection processing of the embodiment.

FIG. 10 is a memory map of the buffer memory 1 during execution of the protection processing of the embodiment.

FIG. 11 is a flowchart of a process in a reproduction operation of the interface control unit 5 of the embodiment.

FIG. 12 is a flowchart of a process in a reproduction operation of the reproduction operation control unit 9 of the embodiment.

FIG. 13 is a flowchart of a process in a reproduction operation of the code processing unit 6 of the embodiment.

FIG. 14 is a memory map of the buffer memory 1 during a reproducing operation of the embodiment.

FIG. 15 is a memory map of the buffer memory 1 after the recording operation of the embodiment.

FIG. 16 is a memory map of the buffer memory 1 after the reproducing operation of the embodiment.

FIG. 17 is a block diagram of a conventional digital data recording / reproducing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Buffer memory 2 RAM 3 Logical address converter 4a Logical bus 4b Physical bus 5 Interface control unit 6 Code processing unit 7 Magnetic recording / reproducing unit 8 Recording operation control unit 9 Reproduction operation control unit 10 Digital transmission circuit 11 Control information storage memory 12 Identification Information storage memory 13 Magnetic tape operation flag register 14 Continuous amble counter

Claims (11)

(57) [Claims] 1. A magnetic tape recording / reproducing means for recording / reproducing a data group, which is data of a fixed capacity, on a magnetic tape as a minimum unit, and logically dividing the data group into a plurality of areas, one data group per area. A buffer memory for temporarily storing a plurality of areas, a control information memory corresponding to each of the plurality of areas and storing control information indicating a processing state of the data group, and a one-to-one correspondence with each of the plurality of areas. 1, an identification information memory for storing identification information for distinguishing the data group, wherein the identification information matches the identification information of a data group including a record specified to be read from an external device, and the control information When indicating that data transfer to the external device is possible, the record is transferred to an external device, and the transferred record includes the record. If the last record of the data group, an interface control means for storing a first control code indicating the completion of the reproducing operation in the corresponding control information memory, and the control information memory is inspected and used as a temporary storage area of a new data group. If a control code meaning possible is found, the identification information of the new data group is stored in the identification information memory corresponding to the control information memory, and the magnetic information is stored in the buffer memory area corresponding to the identification information memory. A reproducing operation control means for transferring a data group reproduced by the tape recording / reproducing means and storing a second control code in the control information memory indicating completion of transfer of reproduction data from the magnetic tape recording / reproducing means. Data recording and playback device. 2. The reproducing operation control means, when detecting that the control information of all the control information memories is not a control code indicating that the control information can be used as a temporary storage area of a new data group, performs the reproducing operation of the magnetic tape recording / reproducing means. When the interface control means detects that the identification information indicated by all of the identification information memories does not match the identification information of the data group including the record specified by the external device, the interface control means controls the data corresponding to the reproduction operation control means. 2. The digital data storage / playback apparatus according to claim 1, further comprising a control procedure for instructing start of playback of a group. 3. When the control information in the control information memory that matches the second control code is found, a decoding process of an error correction code is executed for an area of the buffer memory corresponding to the control information memory, and the decoding is performed. 2. The digital data recording / reproducing apparatus according to claim 1, further comprising a decryption processing means for storing a third control code in the control information memory, which means that data can be transferred to an external device when the decryption processing is completed. 4. A magnetic tape recording / reproducing means for recording / reproducing a data group which is data of a fixed capacity on a magnetic tape as a minimum unit, and logically dividing the data group into a plurality of areas, one data group per area. A buffer memory for temporarily storing data, a control information memory for storing control information indicating a processing state of the data group in one-to-one correspondence with each of the plurality of areas, and a buffer memory for storing each of the plurality of areas.
An identification information memory that stores identification information for identifying the data group corresponding to the pair, and detecting that all the identification information do not match the identification information of the data group including the record whose record is designated by the external device. Then, the control information memory is inspected, and when an area usable as temporary storage information of a new data group is found, the record is transferred to the area from an external device, and the transferred record is a data group of the data group including the record. If the last record, a corresponding control information memory stores a fourth control code indicating the completion of data transfer from the external device, an interface control unit, and the data group to be recorded by the magnetic tape recording / reproducing unit. When it is detected that the control information in the temporarily stored area indicates a recording operable state, Recording operation control means for transferring the data group to the magnetic tape recording / reproducing means, and storing a fifth control code indicating completion of the recording operation in the control information memory upon completion of the transfer. Playback device. 5. When the control information of the control information memory that matches the fourth control code is found, encoding processing of an error correction code is executed for a region of a buffer memory corresponding to the control information memory, and 5. The digital data recording / reproducing apparatus according to claim 4, further comprising an encoding processing means for storing a sixth control code in the control information memory, which means that data can be transferred to the magnetic tape recording / reproducing means when the encoding processing is completed. apparatus. 6. The recording operation control means, upon detecting that the control information of the area where the data group to be recorded by the magnetic tape recording / reproduction means is temporarily stored does not indicate a recording operable state, sets all data to zero. 5. The digital data recording / reproducing apparatus according to claim 4, further comprising a protection process for transferring the constructed special data group to said magnetic tape recording / reproducing means. 7. The recording operation control means, if detecting that the protection processing for transferring a special data group composed of all zero data to the magnetic tape recording / reproduction means has been continuously performed a preset number of times. 7. The digital data recording / reproducing apparatus according to claim 6, further comprising an automatic stop process for stopping the recording operation in said magnetic tape recording / reproducing means. 8. The recording operation control means can select between a first state in which the output of the buffer memory is transmitted to the magnetic tape recording / reproducing means and a second state in which fixed data is always transmitted to the magnetic tape recording / reproducing means. 7. The digital data recording / reproducing apparatus according to claim 6, further comprising a digital transmission circuit. 9. The interface control means according to claim 1, wherein all the identification information in the identification information storage memory does not match the identification information of the data group including the record designated to be recorded by the external device, and all the control information in the control information memory is 5. The digital data recording / reproducing apparatus according to claim 4, further comprising an automatic restart process for requesting the recording operation control means to start a recording operation when detecting that the recording operation is not available as a temporary storage area of a new data group. . 10. The control information is an integer value corresponding to the processing state of the area of the buffer memory on a one-to-one basis. In the reproducing operation, an integer value which increases or decreases in the progressing order of the processing state of the area of the buffer memory is defined. In the recording operation, an integer value that decreases or increases in the reverse order as in the case of the reproduction operation is defined in the order of progress of the processing state of the area of the buffer memory,
5. The digital data recording / reproducing apparatus according to claim 1, wherein the same integer value is defined for the completion state of the reproduction operation and the completion state of the recording operation. 11. An interface control unit, a recording operation control unit, and a reproduction operation control unit can transfer data based on a result of a magnitude comparison between an integer value of control information indicated by the control information memory and a preset reference value. 11. The digital data recording / reproducing apparatus according to claim 10, wherein it is determined whether or not the digital data is recorded.