On 09/08/2017 07:24 AM, Jay Jaeger via cctalk wrote: > On an IBM 1410 (at least - but I suspect this was likely widely true), > tape marks were *always* EVEN parity, 0x0F (Bits 8421), even on an odd > parity tape.
Oh, I know--but remember that I was reading a 7-track tape in a 9-track drive. With the 9-track "scramble" of tracks and the position of the tracks, it makes perfect sense. I'm reading data that isn't massaged by a formatter--this is the (deskewed) output of the read channels. There are a number of documents on bitsavers that explain the 7/9 track differences. As an aside, I know that not all 9 track 800 NRZI drive formatters included the CRC byte before the final LRCC. I'll have to keep an eye out for those. --Chuck
