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⟶ ACL ⟶ Literature ⟶ Progress Reports ⟶ FR80 User :: FR80 User Notes
⟶ ACL ⟶ Literature ⟶ Progress Reports ⟶ FR80 User :: FR80 User Notes
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Further reading ⇓

□ Overview □ User Note 1 □ User Note 2 □ User Note 3 □ User Note 4 □ User Note 5 □ User Note 6 □ User Note 7 □ User Note 8 □ User Note 9 □ User Note 10 □ User Note 11 □ User Note 12 □ User Note 13 □ User Note 14 □ User Note 15 □ User Note 16 □ User Note 17 □ User Note 18 □ User Note 19 □ User Note 20

User Note No 16: Multiple Magnetic Tapes

A H Francis

20 May 1976

1. Introduction

The FR80 is now being used for some long production runs of film, the data for which some times exceeds the size of one magnetic tape. Until recently the user has had to split the job into several shorter jobs each producing less than a full tape of data. A system is now available on the 1906A and will shortly be available on the 360/195 for producing several magnetic tapes for the FR80 from one job.

2. New Routines

Due to restrictions in the FRSO Displayer programs it is necessary to have an advance frame order as the last command on each tape. Therefore after each call to advance the frame the user should test to see if the current tape is almost full and if it is almost full then a new tape should be requested.

The routine 

      BLCNTP(IR,ITYPE)

is called to determine the amount of data output to the current tape so far, where IR is the number of records written to the tape and ITYPE is the tape type. If ITYPE is 1 a 9-track tape is being used, if ITYPE is 0 a 7-track tape is being used and if ITYPE is negative no tape is being used (ie output is going to the spool or some other device). When the tape is almost full, typically after 8000 records for 7-track or 20,000 records for 9-track tapes 2400 feet in length (these figures are approximate and vary from tape to tape) the routine 

      NEXTAP

should be called. This will correctly close the current tape, open a new one of the same type and reset the record count to 0. The new tape is then ready to accept commands for the FR80. If any error restart facilities are in use the program should be dumped at this point. Thus if one of several magnetic tapes were to fail on the FR80 the program could be restarted from its state at the beginning of that tape and finished when the next tape would be called. This would save considerable amounts of computer time when rerunning the job.

These routines can be called from SMOG, SPROGS or SCSIM but should not be used unless large amounts of FR80 data are expected, A separate record count for each tape is written on the user information output stream (LP6 on the 1906A).

Example:

      DO 100 I=1,N 
      ...
C LINE AND/OR TEXT DRAWING COMMANDS 
      ....
C ADVANCE FILM 
      CALL ADVFLM 
C GET CURRENT BLOCK COUNT AND TAPE TYPE 
      CALL BLCNTP(IR,IT) 
      IF(IT)100,70,80 
C HERE IF 7 TRACK 

70    IF(IR-8000)100,90,90 
C HERE IF 9 TRACK 
80    IF(IR-20000)100,90,90 
C THIS TAPE NEARLY FULL SO GET NEXT TAPE 
90    CALL NEXTAP 
C DUMP FOR ERROR RESTART , 
100   CONTINUE 
       ...

3. Tapes on the 1906A

The first owned tape for the job is specified in the normal method by a #MT14 parameter (see Appendix 2 of the SMOG manual or Appendix 12 of the SPROGS manual). When the routine NEXTAP is called this tape is closed and released. The magnetic tape REEL number is then increased by 1 and another tape is requested. If, in the directory in which the job is running, the user already has a tape of the same name and generation number as the previous tape, but with the reel number increased by one, then this tape is used. If the user does not already own such a tape, a pool tape is obtained, it is renamed and then used. The user must have a sufficient magnetic tape budget to be able to obtain tapes in this way. A job may use up to 10 tapes, the reel number being increased by one each time NEXTAP is called, as long as neither the reel number nor the generation number exceed 9. The first tape normally has a reel number and generation number of 0. This system allows the same. set of owned tapes to be used for each run of a job. Work tapes should not be used with this system.

4. Tapes on the 360/195

Currently all FR80 data is routed via the spool so user owned magnetic tapes are not used. A system for outputting to one or more user owned tapes will be made available later.

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