[Simh] query about ibsys tape format

[Richard Cornwell]

Hi Ken,

> Could some one tell me how to interpret an output tape written on 
> sysut3.bin with Fortran WRITE OUTPUT TAPE statements.

  Without seeing the write statements it is hard to tell. But generally
  the SYSUTx tapes are written in binary and not BCD.

> Is bcd2txta the appropriate tool to translate it to something I can
> dump with od or hexdump?

   Like I recommended in my previous email I would use listtape. The
   -b option will convert binary to ascii. Besides BCD, listtape can
   also convert CDC display code, Burroughs BCI, Univac code. 
 
> Where can I read about the tape header or record format?

  Under IBSYS each write statement will be one record. If you use
  Fortran IV under IBJOB you can group records into a block.

> I don't know very much about the tape but output from hexdump shows
> me familiar strings.

  If you want to look at the raw tapes I would recommend using P7B
  format rather then simH. If you use I7090 rather then I7094 you will
  get tapes written with correct parity. For P7B, bit 7 is the record
  mark, bit 6 is the parity (even for BCD, odd for Binary), 5-0 the
  character. SimH tape format as a 4 byte record length before and
  after each record. 

Rich


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Richard Cornwell
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