On Sun, 15 Nov 2020 16:28:02 -0600, Mike Schwab wrote: >They only had 7 track tapes at the time. > >9 track tapes introduced with S/360 in 1964. >https://en.wikipedia.org/wiki/9_track_tape > Which was no obstacle. There were two modes of I/O to 7-track tapes: TRTCH=T, which mapped each tape frame of 6 data bits plus 1 parity to one 8-bit byte. TRTCH=C, which mapped the 24 data bits of 4 tape frames to 3 bytes
I know; I successfully used the latter. I had to argue with ops who tried to tell me that I shouldn't use that; it would corrupt mu data. It didn't. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
