> On Mar 17, 2017, at 11:54 AM, Gary Lee Phillips <tivo.ov...@gmail.com> wrote:
>
> ...
> The tape drive was not TK50. It was standard reel to reel media, horizontal
> like an studio audio tape deck, with a cover that had to be lifted in order
> to use it. The disk drive was housed in the same cabinet in a drawer below
> the tape unit. The tape drive was "finicky" and seemed to work only with
> tapes ordered through DEC. The standard tapes our much larger IBM shop used
> never read back correctly when written on it.
That sounds like a TU80, TU81, TA80, or TA81, all basically the same transport
with variations in density and controller interconnect. Interesting about the
"finicky" thing, I don't have any personal experience with feeding it tapes
from other companies.
FWIW, I just saw a comment that some IBM systems (early 360, perhaps) had a
habit of inserting short gaps into the middle of tape records because of memory
latency issues. Apparently IBM's drives could read such stuff but other
people's drives would not, fair enough since such tapes are not
standards-compliant.
More in general, if drive B wont' read tapes written by drive A, the fault
could be at either end (or both). It could even be in the standard -- all too
many standards, for example a whole lot of modern network protocol standards,
permit implementations that conform but don't interoperate. In some cases, the
authors get annoyed when you point this out and call it a standards bug. (By
contrast, the DECnet standards were always written to the rule that
"conformance implies interoperability".)
paul
_______________________________________________
Simh mailing list
Simh@trailing-edge.com
http://mailman.trailing-edge.com/mailman/listinfo/simh
