Abstract:
A data recording and reproducing apparatus for recording and reproducing data on azimuth tracks of a magnetic tape in which the data may be audio data or computer data in any of several different computer data formats includes a controller that controls the recording and reproducing signal processing so as to be responsive to the four different kinds of data formats such that main data and subdata may be separated from the audio data and subcodes and error correction codes generated and appended to the data stream as required.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the invention 
     This invention relates to a data recording method and apparatus for recording digital audio data or computer data on, a tape-shaped recording medium and to a data reproducing method and apparatus for reproducing digital audio data or computer data from a tape-shaped recording medium. 
     2. Description of the Related Art 
     There has so far been known a digital audio tape recorder (DAT) for recording digital audio signals on a recording track inclined relative to the running direction of a magnetic tape by a rotary head for the purpose of reducing the length of the magnetic tape required for recording. 
     Since the DAT can reduce consumption of the magnetic tape and elevate the data rate during recording, it is preferentially used in a tape recorder, known as a data streamer, used for protecting computer data written on a hard disc. 
     When using the DAT as a tape recorder, data from the host computer is converted into a DAT format data prior to recording. 
     In the DAT format, a frame is completed by two inclined tracks formed during one complete revolution of two heads having different azimuth angles, and 16-bit PCM audio signals are interleaved and recorded on the frame basis. Each track is made up of 196 blocks, each block being formed by 36 bytes. This track is roughly divided into seven areas, as shown in FIG.  1 . 
     Both end marginal areas M are spare areas for realizing stable contact between the tape and the head. Two sub-data areas are those used for recording subcodes which are a variety of signals, such as time or addresses. Two automatic track finding (ATF) areas are those areas for recording the ATF signals and for achieving automatic track finding via the recording head. A main area D is an area for recording main audio data. In this main area D are recorded the main audio data, error correcting parity and part of the subcodes ancillary to the audio data. The main area D is made up of 128 blocks, each being formed by 36 bytes. 
     Each of 128 blocks of the main area D has synchronization signals, PCM-IDs, block addresses and a parity, each of one byte, beginning from the leading end of the block. In the next following 32-byte area is arranged main data. 
     If the data is audio signals, the main data is 16-bit PCM data of the left channel (L) and the right channel (R). This 16-bit main data is interleaved and arranged in the main area of two tracks, that is one frame, along with the parity Q. In this case, approximately 5760 bytes of data are recorded in the main area of one frame. 
     Since each track is divided in the DAT format into a main area and a sub-area, after-recording can be made using the sub-area. 
     The structure of the error correction code of main data in the DAT format is the two-dimensional code, as shown in FIG. 3, with the code planes being, four planes per track, each being coded in C 1  and C 2  directions. 
     If the DAT is used as a data recorder, data sent from the host computer is 16-bit data handled in the same manner as the above-mentioned PCM data. These data are formatted and recorded in the one-frame main area. In this case, data of the two bytes and 16 bits corresponding to L and R channels are used, and upper four bits thereof are used as format ID, while the lower eight bits are recorded as logical frame numbers. The format ID specifies a format proper to the data recorder. The logical frame number has 23 frames, for example, as a unit, and frame numbers of 1 to 23 are attached on the unit basis. 
     With the data recorder, employing such DAT, a higher transfer rate and a larger capacity have recently been realized in keeping up with the progress in the format. The data recorder format is prescribed by, for example, the standard of the European Computer manufacturers Association (ECMA). Recently, the recording density is improved by narrowing the track pitch or changing the recording format, such that a data recorder of the third generation has now been prescribed. 
     The data recorders of the first, second and third generations are termed a DDS (digital data streamer), DDS 2  and DDS 3 , respectively. 
     Meanwhile, audio data for DAT cannot be recorded at present in a tape cassette for DDS 2  nor in a tape cassette for DDS 3 . 
     The above-mentioned DDS 2  and DDS 3  have been utilized as a data recorder for computers, and are not inherently required to have the function of recording or reproducing audio data for DAT. However, if the user in possession of the DDS 2  or DDS 3  desires to record or reproduce audio data for DAT, it is inconvenient if he or she is compelled to purchase a dedicated recording/reproducing apparatus. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a data recording method and apparatus inherently operating as a data recorder and which nevertheless can record audio data for DAT. 
     It is another object of the present invention to provide a data reproducing method and apparatus for reproducing not only computer data but audio data for DAT. 
     In one aspect, the present invention provides a data recording apparatus including recording system signal processing means for performing recording system signal processing on the audio data- or computer data entered via the interface controller, and control means for controlling the recording system signal processing means responsive to four sorts of data format, namely a format for the audio data, a first computer data format comprised of the audio data format added to with error correction provisions in each track width direction in terms of a defined number of tracks, a second computer data format having a track pitch prescribed to be narrower in track pitch than the first computer data format and a third computer data format having a line recording density higher than in the second computer data format. 
     The recording system signal processing means preferably includes separation means for separating main and sub-data of the audio data, subcode generating means for generating sub-codes of the computer data, index appendage means for appending the index information to the computer data, C 3  encoding means for appending the C 3  error correction code to a data string in the track width direction in terms of a defined number of tracks of the computer data having the appended index information, interleaving means for interleaving computer data having an appended C 3  error correction code and separated audio main data, C 2  encoding means for appending the C 2  error correction code to a data string in the track direction of the deinterleaved computer data or audio main data, subcode appendage means for appending the separated audio sub-code to the audio main data and for appending the sub-code of the computer data to the computer data, C 1  encoding means for appending the C 1  error correction code to each defined block unit of audio main data having appended audio sub-codes and computer data having appended computer data subcodes, block-forming means for blocking the audio data or computer data having appended C 1  error correction code and for appending the subcodes for the computer data from the subcode appendage means to the computer main data from the C 1  encoding means and for blocking the resulting data, modulating means for modulating the blocked audio data or computer data and synchronization signal appendage means for appending the synchronization signals to a modulated output of the modulation means. 
     The subcode generating means preferably executes first subcode generating processing or second subcode generating processing if the input computer data is the first or second computer data format or if the input computer data is the third computer data format, respectively. 
     The C 3  encoding means preferably executes first C 3  encoding or second C 3  encoding if the input computer data is of the first or second computer data format or if the the input computer data is of the third computer data format, respectively. 
     The interleaving means preferably executes first interleaving or second interleaving if the input data is of the audio format, first computer data format or the second computer data format or if the input data is of the third computer data format, respectively. 
     The C 2  encoding means preferably executes first C 2  encoding or second C 2  processing if the input data is data of the audio format, first computer data format or the second computer data format processed with the first interleaving, or if the input data is data of the third computer data format processed with the second interleaving. 
     The C 1  encoding means preferably executes first C 1  encoding or second C 1  processing if the input data is data of the audio format, first computer data format or the second computer data format processed with the first C 2  encoding, or if the input data is data of the third computer data format processed with the second C 2  encoding. 
     The subcode appendage means preferably executes first subcode appendage or second subcode appendage if the input data is the subcode of data of the audio format from the separation means, or if the input data is subcode of the third computer data format from the subcode generating means, respectively. 
     The block forming means preferably executes first blocking or second blocking if the input data is data of the audio data format, first computer data format or the second computer data format processed with the first C 1  encoding or if the input data is data of the third computer data format processed with the second C 1  encoding. 
     The modulation means preferably executes first modulation or second modulation if input data is data of the audio data format, first computer data format or the second computer data format or if the input data is data of the third computer data format, respectively. 
     The control means preferably controls the means of the recording system signal processing means depending on a mode designation command of audio or computer data supplied from outside via an interface controller and on the type of a tape-shaped recording medium loaded on recording means provided with a rotary head and which is adapted to record data on the magnetic tape. 
     The control means preferably records the audio data on the tape-shaped recording medium if the audio mode is specified by the mode designating command from outside and if the type of the tape-shaped recording medium is for the second computer data format. 
     The control means preferably advises the user that audio data cannot be recorded on the tape-shaped recording medium if the audio mode is specified by the mode designating command from outside and if the type of the tape-shaped recording medium is for the third computer data format. 
     The control means preferably causes the data of the audio format to be recorded on the tape-shaped recording medium subject to a second command from the user if the audio mode is specified by the mode designating command from the user and if the type of the tape-shaped recording medium is for the second or third computer data format. 
     In another aspect, the present invention provides a data recording method including inputting the audio data or computer data via an interface controller, controlling the recording system signal processing responsive to four sorts of data format, namely a format for the audio data, a first computer data format comprised of the audio data format with error correction provisions in the track width direction in terms of a defined number of tracks as a unit, a second computer data format having a track pitch prescribed to be narrower in track pitch than the first computer data format and a third computer data format having a line recording density higher than in the second computer data format, and recording the audio data or the computer data processed with the recording system signal processing on the magnetic tape. 
     In still another aspect, the present invention provides a data reproducing apparatus including reproducing means for reading out the audio data or the computer data recorded on the magnetic tape using a rotary head, reproducing system signal processing means for processing the read-out data with reproducing system signal processing, and control means for controlling the reproducing system signal processing means in accordance with four sorts of data format, namely a format for the audio data, a first computer data format comprised of the audio data format added to with error correction provisions in each track width direction in terms of a defined number of tracks, a second computer data format having a track pitch prescribed to be narrower than that of the first computer data format and a third computer data format having a line recording density higher than in the second computer data format. 
     The reproducing system signal processing means preferably includes synchronization signal detection means for detecting synchronization signals from data read out from the reproducing means, demodulating means for demodulating the audio or computer data using detected synchronization signals, C 1  decoding means for processing the demodulated audio or computer data with C 1  error correction using the C 1  error correction code, C 2  decoding means for processing the audio or computer data from the C 1  decoding means with C 2  error correction using the C 2  error correction code, deinterleaving means for deinterleaving the audio or computer data from the C 2  decoding means, C 3  decoding means for processing the deinterleaved computer data with C 3  error correction and subcode decoding means for decoding the subcodes from the audio or computer data from the C 1  decoding means and computer data from the demodulating means. 
     The demodulating means preferably processes input data with first demodulation or with second demodulation if input data is data of the audio format, first computer data format or the second computer data format or if the input data is data of the third computer data format. 
     The C 1  decoding means preferably processes input data with first C 1  decoding or with second C 1  decoding if input data is data of the audio format, first computer data format or the second computer data format processed with the first demodulation or if the input data is data of the third computer data format processed with the second demodulation. 
     The C 2  decoding means preferably processes input data with first C 2  decoding or with second C 2  decoding if input data is data of the audio format, first computer data format or the second computer data format processed with the first C 1  decoding or if the input data is data of the third computer data format processed with the second C 1  decoding. 
     The deinterleaving means preferably processes input data with first deinterleaving or with second deinterleaving if input data is data of the audio format, first computer data format or the second computer data format processed with the first C 2  decoding or if the input data is data of the third computer data format processed with the second C 2  decoding. 
     The C 3  decoding means preferably processes input data with first C 3  decoding or with second C 3  decoding if input data is data of first computer data format or the second computer data format processed with the first deinterleaving or if the input data is data of the third computer data format processed with the second deinterleaving. 
     The subcode decoding means preferably processes input data with first subcode decoding, second subcode decoding or with third subcode decoding if input data is data of audio format, if the input data is data of the first computer data format or the second computer data format or if the input data is data of the third computer data format, respectively. 
     The control means preferably controls the reproducing system signal processing means depending on a mode designating command of audio or computer data supplied from outside via interface controller and on the format of data recorded on the tape-shaped recording medium loaded on the reproducing means. 
     If the audio mode is designated from outside and the format of data recorded on the tape-shaped recording medium is the audio format, the control means causes the data of the audio format to be reproduced from the tape-shaped recording medium. If the audio mode is designated from outside, but if the format of data recorded on the tape-shaped recording medium is the computer data format, the control means advises to outside that the computer data cannot be reproduced. 
     In yet another aspect, the present invention provides a data reproducing method including reproducing the audio data or the computer data recorded on the magnetic tape by reproducing means, controlling reproducing system signal processing for reproduced data in accordance with four sorts of data format, namely a format for the audio data, a first computer data format comprised of the audio data format added to with error correction provisions in each track width direction in terms of a defined number of tracks, a second computer data format having a track pitch prescribed to be narrower than that of the first computer data format and a third computer data format having a line recording density higher than in the second computer data format. 
     The data recording apparatus of the present invention, inherently operating as a data recorder for recording data for DDS, DDS 2  and DDS 3 , can also record audio data for DAT. 
     The recording method according to the present invention records can record not only data for DDS, DDS 2  and DDS 3  but also audio data for DAT on an azimuth track of a magnetic tape using a recording device having a rotary head. 
     The data reproducing apparatus can reproduce not only computer data for DDS, DDS 2  and DDS 3 , but also audio data for DAT. 
     In addition, the data reproducing method according to the present invention can reproduce not only DDS, DDS 2  or DDS 3  data but also audio data for DAT from an azimuth track on the magnetic tape using a reproducing apparatus having a rotary head. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a track format in the DAT format. 
     FIG. 2 shows a block format of main data in the DAT format. 
     FIG. 3 shows the structure of an error correction code of main data in the DAT format. 
     FIG. 4 is a block diagram of a data streamer embodying the present invention. 
     FIG. 5 is a flowchart for illustrating the operation of a specified example of a data recording apparatus constituting the data streamer. 
     FIG. 6 illustrates the processing operation under modes A, D 1 , D 2  or D 3  of a signal processing unit of the recording system constituting a specified example of the data recording device. 
     FIG. 7 is a flowchart for illustrating another exemplary operation of a specified example of the data recording apparatus constituting the data streamer. 
     FIG. 8 is a flowchart for illustrating the operation of a specified example of a data reproducing apparatus constituting the data streamer. 
     FIG. 9 illustrates the processing operation under modes A, D 1 , D 2  or D 3  of the signal processing unit of the reproducing system constituting the specified example of the data reproducing apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, preferred embodiments of a data recording method and device and a data reproducing method and device according to the present invention will be explained in detail. These embodiments are directed to a data streamer adapted for recording audio data or computer data on azimuth tracks on a magnetic tape by a rotary head and for reproducing the recording audio data or computer data from the magnetic tape. The data recording method and the data recording device are implemented by this data streamer. 
     The data streamer embodying the present invention, shown in FIG. 4, includes an interface controller  10 , for controlling the input/output of data from e.g., a small computer interface (SCSI), adapted for exchanging data with an external equipment, such as a host computer, and a recording system signal processor  20  for processing input data from the interface controller  10  for converting the data into signals of a defined format. The data streamer also includes a recording/reproducing unit  40  for recording signals supplied from the recording system signal processor  20  on the azimuth tracks on the recording tape  42  by paired rotary magnetic heads  41   a,    41   b  and for reproducing the signals recorded on the azimuth tracks by the rotary magnetic heads  41   a,    41   b,  and a reproducing system signal processor  50  for processing reproduced signals from the recording/reproducing unit  40  to reproduce original signals. The data streamer further includes a tracking controller  60  for controlling the tape running system of the recording/reproducing unit  40  and a controller  70  for controlling the above respective components. 
     This data streamer functionally accepts loading (insertion) into the recording/reproducing unit  40  of the tape cassette for the DAT, in addition to the tape cassette of the first generation DDS, prescribed by the ECMA standard, the tape cassette of the second generation DDS 2  and the tape cassette of the third generation DDS 3 . 
     If the data mode for the computer data is selected, the, data streamer records/reproduces data by the formats of the respective generations conforming to the types of the inserted tape cassettes. If the audio mode is selected, and the tape cassette for DAT is inserted, the data streamer records/reproduces the audio data. 
     During recording, when the audio mode is selected and nevertheless the tape cassette for the DDS 2  is inserted, audio data for DAT is directly recorded. If the audio mode is selected and nevertheless the tape cassette for the DDS 3  is inserted, the external computer is advised of the effect that recording cannot be made. 
     During reproduction, when the audio mode is selected, and nevertheless the tape cassette for the DDS 2  or the tape cassette for the DDS 3  is inserted, the audio data is reproduced only if the format of data recorded on the tape cassette is the audio format. If the data format is the computer data format, the external computer is advised of the effect that recording cannot be made. 
     In the following, the formats of the data streamers DDS, DDS 2  and DDS 3  for recording/reproducing computer data are abbreviated to D 1 , D 2  and D 3 , respectively, while the DAT format is depicted as A. 
     The data streamer records/reproduces data of the four formats A, D 1 , D 2  and D 3 , that is audio data, computer D 1  data, computer D 2  data and computer D 3  data. These four formats are as shown in Table 1 below. 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 format 
                 A 
                 D1 
                 D2 
                 D3 
               
               
                   
               
             
             
               
                 capacity (GB) 
                 120 min 
                 1.3/2 
                 4 
                 12 
               
               
                 tape length (m) 
                 60 
                 60/90 
                 120 
                 120 
               
               
                 track pitch (μm) 
                 13.6 
                 13.6 
                 9.1 
                 9.1 
               
               
                 line recording density 
                 61 
                 61 
                 61 
                 122 
               
               
                 (KBPI) 
               
               
                 modulation system 
                 8/10 
                 ← 
                 ← 
                 new 8/10 
               
               
                 ECC 
               
               
                 C1 
                 (32, 28, 5) 
                 ← 
                 ← 
                 (62, 56, 7) 
               
               
                 C2 
                 (32, 26, 7) 
                 ← 
                 ← 
                 ← 
               
               
                 C3 
                 — 
                 (46, 43, 3) 
                 ← 
                 ← 
               
               
                 interleaving 
               
               
                 data 
                 DAT system 
                 ← 
                 ← 
                 new 
               
               
                 C1 
                 2 symbols 
                 ← 
                 ← 
                 ← 
               
               
                 C2 
                 4 blocks 
                 ← 
                 ← 
                 3 blocks 
               
               
                 C3 
                 — 
                 1 track 
                 ← 
                 ← 
               
               
                 block length 
                 36 bytes 
                 ← 
                 ← 
                 133 bytes 
               
               
                 track 
                 196 blocks 
                 ← 
                 ← 
                 96 blocks 
               
               
                 group 
                 — 
                 46 tracks 
                 ← 
                 ← 
               
               
                   
               
             
          
         
       
     
     The format A is the format for recording audio data, with the tape capacity being 120 minutes and the tape length being 60 m. The track pitch is 13.6 μm, with the line recording density being 61 KBPI. The modulation system is 8/10 modulation, with the error correction codes being C 1  and C 2 . The interleaving system for data is the DAT system. The C 1  and C 2  codes are interleaved every two symbols and every four symbols, respectively. As for the data structure, each track is constituted by 196 blocks, each block being of 36 bytes. 
     In the format D 1 , the recording capacity is 1.3/2 Gbyte (GB), with the tape length being 60/90 m. The track pitch, line recording density and the modulation system are the same as those of the format A. As for the ECC, an error correction code C 3  is appended in the track width direction every pre-set number of tracks, for example, every 46 tracks, in addition to the above-mentioned C 1  and C 2 . The interleaving is every other track for C 3 . Each track is formed by 196 blocks, each block being of 36 bytes. In this manner, the format D 1  is basically the format A changed so as to be usable for data. Therefore, audio data can be recorded on a tape cassette for D 1 . 
     On the other hand, in the format D 2 , the tape length is increased to 120 m, while the track pitch is reduced to 9.1 μm. The line recording density, modulation system, ECC, interleaving, block length, track structure and groove formation are similar to those of the above-mentioned format D 1 . However, the recording capacity can be substantially doubled by technical improvement in the tape length and track pitch. 
     In the format D 3 , the recording capacity can be substantially trebled to 12 GB by improving the track format as later explained, in addition to doubling the line recording density to 122 kBPI, despite the fact that the tape length and the track pitch are the same as those of the format D 2 . The modulation system used is the new 8/10 modulation system, while the ECC and interleaving are also be changed slightly. It is the track format that has been changed significantly. That is, each track is made up of 96 blocks, each block being of 133 bytes. 
     In the data streamer, shown in FIG. 4, the recording system signal processor  20  and so forth are controlled by the controller  70  for absorbing the differences in the four formats shown in table 1. Meanwhile, in FIG. 4, control lines for controlling various parts of the recording system signal processor  20  and the reproducing system signal processor  50  by the controller  70  are not shown. 
     The recording system signal processor  20  includes a separation circuit  21  for separating audio (A) data sent from the host computer via interface controller into audio main (AM) data and audio sub(AS) data, and a subcode generating circuit  22  for generating data sub (DS) codes from the computer data main (DM) sent in similar manner. The recording system signal processor  20  also includes an index appendage circuit  23  for appending the index information to the computer data main DM and a C 3  encoder  24  for appending an error correction code C 3  to the data main DM&#39; from the index appendage circuit  23 . The recording system signal processor  20  also includes an interleaving circuit  25  for interleaving the data main from the C 3  encoder  24  and the audio main AM from the separation circuit  21 , and a C 2  encoder  26  for appending the error correction code C 2  to an interleaved output of the interleaving circuit  25 . The recording system signal processor  20  also includes a C 1  encoder  28  for appending the error correction code C 1  to the computer data system of the encoded output of the C 2  encoder  26  and for appending C 1  to the audio data system using the subcode from a subcode appendage circuit  27  and a block generating circuit  29  for blocking an audio system of the encoded output of the C 1  encoder  28  and for blocking the data system using the subcode from the subcode appendage circuit  27 . The recording system signal processor  20  also includes an 8/10 modulating circuit  30  for 8/10 modulating a block data output of the block generating circuit  29  to generate 10-bit data and a synchronization signal appendage circuit  31  for appending synchronization signals to 10-bit data from the 8/10 modulation circuit  30 . The recording system signal processor  20  further includes a margin appendage circuit  32  for appending the margin to man data to which has been appended the synchronization signal by the synchronization signal appendage circuit  31  and an amplifier  33  for amplifying data to which the margin has been added by the margin appendage circuit  32 . 
     The C 3  encoder  24 , C 2  encoder  26  and the C 1  encoder  28  make up an error correction code generator in cooperation with the memory  34 . In this error correction code generator, the memory  34  stores main data to which has been appended the index information by the index appendage circuit  23 . The C 3  encoder  24  generates the error correction code C 3  of a data string in the track width direction to append the code C 3  to the data string in terms of 46 tracks as a unit. The C 2  encoder generates an error correction code C 2  of a data string in the track direction and splits the code C 2  into two portions which are allocated to both end portions of the main data area of each track. The C 1  encoder  28  generates the block-based error correction code C 1 . 
     The separation circuit  21  separates various subcodes S for time, addresses or the like, making up the audio data, as shown in FIG. 1, as the data subcode DS, from the audio main AM of the main area. 
     The subcode generating circuit  22  generates separator counters, as the division information specifying the divisions of computer data, and record counts, specifying the number of records. The subcode generating circuit  22  also automatically generates area IDs specifying various areas defined on the tape format, frame numbers, group counts specifying the number of record units, and the check sum, along with the block addresses. The subcode generating circuit  22  also generates the hysteresis information (system log). 
     The block generating circuit  29  collects the audio data and the computer data in terms of 36 or 133 bytes as a unit to produce blocks. At this time, two-byte parity for error detection is added to the subcodes appended to main data. 
     The 8/10 modulation circuit  30  converts the blocked data from 8 bits to 10 bits on the byte basis. The synchronization signal appendage circuit  31  appends the synchronization signals on the block basis to data converted by the 8/10 modulation circuit  30  into 10-bit data. 
     The margin appendage circuit  32  appends margins on the track basis to the data having appended synchronization signals. The data having the margins appended thereto on the track basis by the margin appendage circuit  32  are sent via amplifier  33  to the recording/reproducing unit  40 . 
     The recording/reproducing unit  40  has a rotary drum  41  carrying paired rotary magnetic heads  41   a ,  41   b  adapted for providing a track pitch of, for example, 9.1 μm, in order to permit the magnetic tape  42  to be run at a defined running speed, with the magnetic tape  42  being wrapped around the rotary drum  41  over an angular extent of approximately 90°. The rotary magnetic heads  41   a ,  41   b  scan the two azimuth tracks on the magnetic tape  42  per each complete revolution of the rotary drum  41  to record/reproduce signals. 
     In the present embodiment of the data streamer, the reproducing system signal processor  50  includes an amplifier  51  for amplifying signals reproduced from the azimuth tracks of the magnetic tape  42  by the recording/reproducing unit  40 , and a synchronization signal detection circuit  52  for detecting the synchronization signals from the reproduced signals amplified by the amplifier  51  to output resulting bi-level playback signals. The reproducing system signal processor  50  also includes a 10/8 demodulation circuit  53  for 10/8 demodulating the bi-level playback data from the synchronization signal detection circuit  52 , and a C 1  decoder  54  for decoding the D 3  subcode from the 10/8 demodulation circuit  53  and for correcting the block data for errors using the error correction code C 1  appended to each block. The reproducing system signal processor  50  also includes a subcode decoding circuit  55  for decoding the subcodes from the audio A or D 1  and D 2  data from the C 1  decoder  54  and the 10/8 demodulation circuit  53 , and a C 2  decoder  56  for correcting the data string in the track direction for errors using the error correction code C 2  for each unit data corrected for errors by the C 1  decoder  54 . The reproducing system signal processor  50  also includes a deinterleaving circuit  57  for deinterleaving data corrected for errors by the C 2  decoder  56  in order to supply the audio main AM both to the interface controller  10  and to a C 3  decoder  58 , the C 3  decoder  58  for error-correcting the data string of the deinterleaved data from the deinterleaving circuit  57  in terms of 46 tracks as a unit, and an index decoding circuit  59  for decoding the index information appended to a decoded output from the C 3  decoder  58  to route the data main DM to the interface controller  10 . 
     The synchronization signal detection circuit  52  detects synchronization signals from the playback signals supplied from the recording/reproducing unit  40  via amplifier  51  to convert the playback signals into bi-level signals by clocks synchronized with the synchronization signals to generate playback data. 
     The 10/8 demodulation circuit  53  converts 10-bit playback data from the in synchronization signal detection circuit  52  into corresponding 8-bit data by way of performing 10/8 demodulation in association with the operation executed by the 8/10 modulation circuit  30  of the recording system signal processor  20 . 
     The C 1  decoder  54 , C 2  decoder  56  and the C 3  decoder  58  constitute an error correction processor in cooperation with the memory  34 . In this error correction processor, the memory  34  transiently stores data having the appended index information with the above-mentioned 46 track or 23 frame data as a unit. This memory  34  is used in common with the error correction generator of the recording system signal processor  20 . 
     The C 1  decoder  54  corrects the main data of each block stored in the memory  34  using the error correction code C 1  appended on the block basis. The C 2  decoder  56  also error-corrects the data string in the track direction of the data corrected for errors by the C 1  decoder  54 , using the error correction code C 2  appended to both end portions of the main data area of each track. The C 3  decoder  58  also error-corrects the data string in the track width direction of the main data, error-corrected by the C 2  decoder  56 , using the error correction code C 3  allocated to the above-mentioned  46  tracks as unit. 
     The index decoding circuit  59  decodes the index information, appended to the data corrected for errors by the error correction processor, and routes the data main DM via interface controller  10  to the host computer based on the index information. 
     The tracking controller  60  in the present embodiment of the data streamer includes a block address detection circuit  61  fed with block addresses from the reproducing system signal processor  50  via the 10/8 demodulation circuit  53 , a PG pulse detection circuit  62  fed with the PG pulses from the recording/reproducing unit  40 , a time detection circuit  63  fed with detection outputs of the block address detection circuit  61  and the PG pulse detection circuit  62 , a tracking servo circuit  64  fed with a detection output of the tracking servo circuit  64  and a capstan driving circuit  65  fed with an output of the tracking servo circuit  64 . 
     In the tracking controller  60  the block address detection circuit  61  detects the correct block address from the 10/8 demodulation circuit  53  to send a detection output specifying its detection timing to the time detection circuit  63 . The time detection circuit  63  detects the time between the timing the block address detection circuit  61  has detected a defined block address and the timing the PG pulse detection circuit  62  has detected the PG pulse. It is noted that the time detected by the time detection circuit  63  is changed from the time in the just-tracking state depending on the tracking error. 
     The tracking servo circuit  64  detects the time difference between the reference time under the just-tracking state and the time as detected by the time detection circuit  63 , that is the tracking error, in order to control the capstan driving circuit  65 , adapted for driving the tape running system of the recording/reproducing  40 , and in order to reduce the tracking error to zero based on the detection output. 
     The controller  70  controls the operation of the recording system signal processor  20 , recording/reproducing unit  40  and the reproducing system signal processor  50  based on the command supplied from the host computer via interface controller  10 . 
     In particular, when controlling the recording system signal processor  20 , the controller  70  refers to the data subcode from the subcode generating circuit  22 . When controlling the reproducing system signal processor  50 , the controller  70  refers to the data sub DS from the subcode decoding circuit  55 . 
     The above-mentioned recording system signal processor  20 , recording/reproducing unit  40 , tracking controller  60  and the controller  70  can make up a specified embodiment of the data recording apparatus according to the present invention. 
     The present specified embodiment records the audio data or the computer data in accordance with the flowchart shown in FIG.  5 . First, at step S 1 , the controller  70  checks whether or not a command specifying the audio A mode has been sent from the host computer. If the controller  70  verifies that the A mode has been specified, the program shifts to step S 2  and, if otherwise, the program shifts to step S 3 . Meanwhile, the present data streamer basically operates in the mode specified at step S 1  or step S 3 , irrespective of the type of the tape cassette loaded in the recording/reproducing unit  40 . 
     At step S 2 , the controller verifies whether or not the tape cassette loaded on the recording/reproducing unit  40  is a D 2  or D 3  cassette. If the controller verifies that the tape cassette inserted is the D 2  or D 3  cassette, the program shifts to step S 4  and, if otherwise, the program shifts to step S 5 . 
     At step S 3 , the controller  70  checks whether the mode specified by the host computer is the computer data D mode. If the result is YES, that is if the D mode is found to have been specified, the program shifts to step S 6 . If the result is NO, that is if the D mode is found not to have been specified, the program reverts to step s 1 . 
     At step S 4 , it is checked, based on the result of decision at step S 2 , whether or not the loaded tape cassette is the D 2  cassette. If the result is YES, that is if the tape cassette is found to be the D 2  cassette, the program shifts to step S 7  to record the audio data on the D 2  tape cassette. 
     If the result of check at step S 4  is NO, that is if the tape cassette is the D 3  cassette, the program shifts to step S 8 , in order to advise the host computer that the tape cassette is the D 3  cassette and hence cannot be operated in the audio mode. 
     At step S 5 , it is checked whether or not the D 1  or A cassette has been loaded on the recording/reproducing unit  40 . If the result of check at step S 5  is YES, that is if it is verified that the D 1  or A cassette has been loaded on the recording/reproducing unit  40 , the program shifts to step S 7  to operate in the A mode. If the result is NO, that is if it is verified that the loaded tape cassette is not the D 1  or A cassette, the program shifts to step S 9  to notify to the host computer that, as a result of check at steps S 2  and S 5 , the loaded tape cassette cannot be accepted by the present data streamer. 
     At step S 6 , the controller  70  checks, based on the result of step S 3 , indicating that the mode specified by the host computer is the computer data mode, whether or not the tape cassette loaded on the recording/reproducing unit  40  is the D 1  or A cassette. If the result is YES, that is if the loaded tape cassette is the D 1  or A cassette, the program shifts to step S 10  to operate in the D 1  mode. If the result is NO, that is if the loaded tape cassette is not the D 1  nor A cassette, the program shifts to step S 11  to verify whether or not the loaded tape cassette is the D 2  cassette . 
     If the loaded tape cassette is found at step S 11  to be the D 2  cassette, the program shifts to step S 12  to operate in the D 2  mode. If the result of check at step S 11  is NO, the program shifts to step S 13 . 
     At step S 13 , it is checked whether or not the loaded tape cassette is the D 3  cassette. The program shifts to steps  14  to operate in the D 3  mode. If the result is NO, that is if the loaded tape cassette is not the D 3  tape cassette, the program shifts to step S 15  to notify to the host computer that the loaded tape cassette is not acceptable. 
     The recording operation of the specified example of the data recording apparatus at steps S 7 , S 10 , S 12  and S 14  is explained in detail with reference to FIG.  6 . 
     This specified example of the data recording apparatus operates in any of the A mode, D 1  mode, D 2  mode or the D 3  mode. The recording operation is executed by the controller  70  switching among the operations of separation by the separation circuit  21 , subcode generation by the subcode generating circuit  22 , index appendage by the index appendage circuit  23 , C 3  encoding by the C 3  encoder  24 , subcode appendage by the subcode appendage circuit  27 , interleaving by the interleaving circuit  25 , C 2  encoding by the C 2  encoder  26 , C 1  encoding by the C 1  encoder  28 , block generation by the block generating circuit  29 , 8/10 modulation by the 8/10 modulation circuit  30  and synchronization signal appendage by the synchronization signal appendage circuit  31 , depending on the A mode, D 1  mode, D 2  mode or the D 3  mode. 
     The controller  70  performs control so that, if the computer data entered via the interface controller  10  is of the above-mentioned D 1  format or the above-mentioned D 2  format, the processing by the subcode generating circuit  22  is the first subcode generating processing performed by a first subcode generating section  22   1  and so that, if the computer data entered via the interface controller  10  is the above-mentioned D 3  format, the processing by the subcode generating circuit  22  is the second subcode generating processing performed by the second subcode generating section  22   2 . 
     The controller  70  also performs control so that, if the computer data from the index appendage circuit  23  is of the D 1  format or the D 2  format, the C 3  encoding by the C 3  encoder fed with such computer data is the first C 3  encoding executed by a C 3  encoding section  24   1 , and so that, if the computer data is of the D 3  format, the C 3  encoding by the C 3  encoder fed with such computer data is the second C 3  encoding executed by the C 3  encoding section  24   2 . 
     The controller  70  also performs control so that, if the input data, that is the audio main data AM from the separation circuit  21  and computer data from the C 3  encoding circuit  24 , is of the audio A format, D 1  format or the D 2  format, the interleaving processing in the interleaving circuit  25  fed with the above audio and computer data is the first interleaving processing executed by a first interleaving section  25   1 , and so that, if the above input data is of the D 3  format, the interleaving processing in the interleaving circuit  25  fed with the above audio and computer data is the second interleaving executed by a second interleaving section  25   2 . 
     The controller  70  also performs control so that, if the input data is the data of the format A, format D 1  or the Format D 2  processed by the interleaving circuit  25  with first interleaving, the C 2  encoding performed by the C 2  encoder  26  is the first C 2  encoding executed by a first C 2  encoding section  26   1 , and so that, if the above input data is data of the D 3  format, processed by the interleaving circuit  25  with the second interleaving, the interleaving processing in the interleaving circuit  25  is the second C 2  encoding executed by a second encoding section  26   2 . 
     The controller  70  also performs control so that, if the input data is the data of the format A, format D 1  or the Format D 2  processed by the C 2  encoder  26  with first C 2  encoding, the C 1  encoding performed by the C 1  encoder  28  is the first C 1  encoding executed by a first C encoding section  28   1 , and so that, if the above input data is data of the D 3  format, encoded by the C 2  encoder  26  with the second C 2  encoding, the interleaving processing in the interleaving circuit  25  is the second C 1  encoding executed by a second C 1  encoding section  28   2 . 
     The controller  70  also performs control so that, if the input data is the subcode AS of data of the A format from the separation circuit  21 , the subcode appending processing by the subcode appendage circuit  27  is the first subcode appendage processing executed by a first subcode appendage processing section  27   1 . The controller  70  also performs control so that, if the input data is the subcode D 1 S of the format D 1  or the subcode D 2 S of the format D 2  from the subcode generating circuit  22 , the subcode appending processing by the subcode appendage circuit  27  is the second subcode appendage processing executed by a second subcode appendage processing section  27   2  and so that, if the input data is the subcode D 3 S of the D 3  format from the subcode generating circuit  22 , the subcode appending processing by the subcode appendage circuit  27  is the third subcode appendage processing executed by a third subcode appendage processing section  27   3 . 
     The controller  70  also performs control so that, if the input data is the data of the A format, D 1  format or the D 2  format from the C 1  encoder  28 , the block generating processing by the block generating circuit  29  is the first block generating processing executed by a first block generating processor  29   1  and so that, if the input data is the data of the format D 3  format from the C 1  encoder  28 , the block generating processing by the block generating circuit  29  is the second block generating processing executed by a second block generating processor  29   2 . 
     The controller  70  also performs control so that, if the input data is the data of the A format, D 1  format or the D 2  format from the block generating circuit  29 , the 8/10 modulation by 8/10 modulation circuit  30  is the first modulation executed by a first modulation section  30   1  and so that, if the input data is the data of the format D 3  format from the block generating circuit  29 , the 8/10 modulation by 8/10 modulation circuit  30  is the second modulation executed by a second modulation section  30   2 . 
     The controller  70  controls the recording processing by the recording system signal processor  20 , depending on the mode designation for audio or computer data sent from the outside via interface controller  10 , and the type of the tape cassette loaded on the recording/reproducing unit  40 , as shown by the flowchart of FIG.  5 . 
     The above-described embodiment of the data recording device records data with the format of each generation corresponding to the type of the inserted tape cassette when the computer data mode is selected. If the audio mode is selected, and the DAT tape cassette is inserted, the recording device records the audio data. 
     If the audio mode is selected, and the DDS 2  tape cassette is inserted, the audio data directly is recorded. On the other hand, if the audio mode is selected but the DD 3  tape cassette is inserted, the effect that audio data cannot be recorded is advised to the host computer. 
     In the present specified embodiment of the data recording device, the rotational speed of the rotary drum  41  of the recording/reproducing unit  40 , the average data transfer rate and the SCSI transfer rate via interface controller  10  is switched from mode to mode under control by the controller  70 . 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 mode 
                 A 
                 D1 
                 D2 
                 D3 
               
               
                   
               
             
             
               
                 rotational speed of drum (rpm) 
                 4251 
                 4251 
                 4251 
                 4251 
               
               
                 average transfer rate (KBPS) 
                 408 
                 389 
                 389 
                 1180 
               
               
                 SCSI transfer rate (MBPS) 
                 10 
                 10 
                 10 
                 10 
               
               
                   
               
             
          
         
       
     
     That is, for the A mode, the drum rpm is set to 4251, the average transfer rate is set to 408 kBPS and the SCSI transfer rate is 10 MBPS, whereas, for D 1  and D 2  modes, only the average transfer rate is changed to 389 kBPS. For the D 3  mode, the average transfer rate is changed to 180 kBPS. This absorbs the difference in, for example, the track pitch or the line recording density during recording from one data format to another. 
     In the present specified embodiment of the data recording device, audio data or computer data can be recorded in accordance with the flowchart shown in FIG.  7 . The difference of the flowchart from that shown in FIG. 5 resides in elimination of steps S 4  and S 8  and addition of steps S 17 , S 18 . 
     That is, in the present specified embodiment, if it is found at step S 2  in the flowchart of FIG. 7 that the tape cassette inserted is the D 2  or D 3  cassette, the program shifts to step S 17  to advise the host computer of the effect that recording in the audio mode is not possible. If the audio mode is re-designated at step S 18 , the program shifts to step S 7  to operate at the audio mode. That is, the recording device operates in the audio mode despite the fact that the tape cassette loaded on the recording/reproducing  40  is that for D 2  or D 3 . 
     The above-described specified embodiment can record the audio data on all of the four sorts of the tape cassettes. 
     Returning to FIG. 4, the reproducing system signal processor  50 , recording/reproducing unit  40 , tracking controller  60  and the controller  70  make up a specified embodiment of the data reproducing device according to the present invention. 
     The present specified embodiment reproduces the audio data or computer data in accordance with the flowchart shown in FIG.  8 . First, at step S 21 , the controller  70  checks whether or not a command specifying the audio A mode has been supplied from the host computer. If the controller  70  finds that the A mode has been designated, the program shifts to step S 22  and, if otherwise, the program shifts to step S 25 . 
     At step S 22 , it is checked whether or not the data recorded on the tape cassette loaded on the recording/reproducing unit  40  is of the audio format. If the result of check is YES, that is if the recorded data is of the audio format, the program shifts to step S 23  to reproduce audio data from the loaded tape cassette. 
     Meanwhile, the format check is rendered possible by having, reference to the format ID in the main ID and/or data ID of sub-ID of the data recorded on the tape. 
     If the result of check at step S 22  is NO, that is if the format is not the audio format, the program shifts to step S 24  to advise the host computer of the fact that the data recorded on the loaded tape cassette is not of the audio format and hence cannot be reproduced. 
     At step S 25 , it is checked whether or not the mode designated by the host computer is the computer data D mode. If the result of the check is YES, that is if the D mode has been designated, the program shifts to step S 26  and, if otherwise, the flow reverts to step S 21 . 
     At step S 26 , it is checked whether the cassette loaded is the D 1  cassette or the A cassette, based on the result of check of step S 25  indicating that the mode specified by the host computer is the computer data mode. If the result of the check is YES, that is if the cassette loaded is the D 1  or A cassette, the program shifts to step S 27  to operate under the D 1  mode to reproduce computer data. Conversely, if the result of the check is NO, that is if the cassette loaded is not the D 1  nor A cassette, the program shifts to step S 28  to give decision whether or not the loaded cassette is the D 2  cassette. 
     If the cassette loaded is found at step S 28  to be a D 2  cassette, the program shifts to step S 29  to operate in the D 2  mode to reproduce computer data. If the result of the check is NO, the program shifts to step S 30 . 
     At step S 30 , it is checked whether or not the cassette loaded on the recording/reproducing unit  40  is the D 3  cassette. If the result of the check is YES, that is if the loaded cassette is the D 3  cassette, the program shifts to step S 31  to operate in the D 3  mode to reproduce computer data. If the result of the check is NO, that is if the loaded cassette is found to be not for D 3 , the program shifts to step S 32  to advise the host computer of the effect that the loaded cassette is not acceptable. 
     The recording operation of the specified embodiment of the data recording device at steps S 23 , S 27 , S 29  and S 31  is explained by referring to FIG.  9 . 
     This specified embodiment of the data reproducing device is such a device which reproduces data in any one of the A mode, D 1  mode, D 2  mode or the D 3  mode. The reproducing operation occurs by the controller  70  switching between detection of synchronization signals by the synchronization signal detection circuit  52 , 10/8 demodulation by the 10/8 demodulation circuit  53 , C 1  decoding by the C 1  decoder  54 , C 2  decoding by the C 2  decoder  56 , subcode decoding by the subcode decoding circuit  55 , deinterleaving by the deinterleaving circuit  57 , C 3  decoding by the C 3  decoder  58  and index decoding by the index decoding circuit  59  in association with the A 1  mode, D 1  mode, D 2  mode or the D 3 e mode. 
     If the data fed via the synchronization signal detection circuit  52  is the data of A 1 , D 1  or D 2  format, the controller  70  manages control so that demodulation by the 10/8 demodulation by the 10/8 demodulation circuit  53  will be the first demodulation performed by a first demodulation unit  53   1 . If the data fed via the synchronization signal detection circuit  52  is the data of the D 3  format, the controller  70  manages control so that demodulation by the 10/8 demodulation by the 10/8 demodulation circuit  53  will be the second demodulation performed by a second demodulation unit  53   2 . 
     If the input data is the data of the A, D 1  or D 2  format processed by first demodulation by the 10/8 demodulation circuit  53 , the controller  70  manages control so that control so that the C 1  decoding by the C 1  decoder  54  will be the first C 1  decoding performed by the first C 1  decoding processor  54   1 . If the input data is the data of the format D 3  processed with the second demodulation, the controller  70  manages control so that the C 1  decoding by the C 1  decoder  54  will be the second C 1  decoding performed by the second C 1  decoding processor  54   2 . 
     If the input data is the data of the A, D 1  or D 2  format processed by first demodulation by the C 1  decoder  54 , the controller  70  manages control so that the C 2  decoding by the C 2  decoder  56  will be the first C 2  decoding performed by the first C 2  decoding processor  56   1 . If the input data is the data of the format D 3  processed with the second C 1  decoding, the controller  70  manages control so that the C 2  decoding by the C 2  decoder  56  will be the second C 2  decoding performed by the second C 2  decoding processor  56   2 . 
     If the input data is the data of the A, D 1  or D 2  format processed by first C 2  decoding by the C 2  decoder  56 , the controller  70  manages control so that the interleaving by the deinterleaving circuit  57  will be the first deinterleaving performed by the first C 2  deinterleaving processor  57   1 . If the input data is the data of the format D 3  processed with the second C 2  decoding, the controller  70  manages control so that deinterleaving by the deinterleaving circuit  57  will be the second deinterleaving performed by the second deinterleaving processor  57   2 . 
     If the input data is the data of the A, D 1  or D 2  format processed by first deinterleaving by the deinterleaving circuit  57 , the controller  70  manages control so that C 3  decoding by the C 3  decoder  58  will be the first C 3  decoding performed by the first C 3  decoding processor  58   1 . If the input data is the data of the format D 3  processed with the second C 2  deinterleaving, the controller  70  manages control so that C 3  decoding by the c 3  decoder  58  will be the second C 3  decoding performed by the second C 3  decoding processor  58   2 . 
     If the input data is the data of the A format processed by subcode decoding by the C 1  decoder  54 , the controller  70  manages control so that subcode decoding by the subcode decoding circuit  55  will be the first subcode decoding performed by the first subcode decoding processor  55   1 . If the input data is the data of the format D 1  or D 2 , the controller  70  manages control so that subcode decoding by the subcode decoding circuit  55  will be the second subcode decoding performed by the second subcode decoding processor  55   2  and, if the input data is the data of the format D 3 , the controller  70  manages control so that subcode decoding by the subcode decoding circuit  55  will be the third subcode decoding performed by the third subcode decoding processor  55   3 . 
     The controller  70  controls the above-mentioned processing of the reproducing system signal processor  50  depending on the mode designation of the audio or computer data supplied from outside via interface controller  10  and the format of data recorded on the tape cassette loaded on the recording/reproducing unit  40 , as shown in the flowchart of FIG.  8 . 
     If the computer data mode is designated, the above-described specified embodiment of the data reproducing device reproduces data with the format of each generation depending on the type of the loaded tape cassette. If the audio mode is selected and the tape cassette inserted in the tape cassette for DAT, the audio data is reproduced. 
     If the audio mode is selected but the tape cassette of the DDS 2  or DDS 3  is inserted, the audio data is reproduced only if the format of the data recorded on the tape is the audio format. If the data recorded on the tape is the computer data format, the effect that the data cannot be reproduced is transmitted to the lost computer. 
     In the present specified embodiment of the data recording device, the rotational speed of the rotary drum  41  of the recording/reproducing unit  40 , average data transfer rate and the SCSI transfer rate via the interface controller  10  are changed over from one mode to another, under control by the controller  70 , as shown in the above Table 2. 
     The data streamer of the above-described embodiment, made up of the specified embodiment of the data recording device and the specified embodiment of the data reproducing device, can record/reproduce data of the four formats of A, D 1 , D 2  and D 3 , that is audio data and computer D 1 , D 2  and D 3  data.