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From: John Savard <quadibloc@servername.invalid>
Newsgroups: comp.arch
Subject: Re: wisdom of the ancients, was Architectural implications of locate mode I/O
Date: Wed, 03 Jul 2024 22:17:59 -0600
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On Wed, 3 Jul 2024 23:03:24 -0000 (UTC), John Levine <johnl@taugh.com>
wrote:

>That is pretty amazing.  Did NASA have a plan for reading
>those tapes, or did they not realize that normal tape units
>need record gaps, or what?

It would be interesting to find out the real historical answer to that
question.

But I can guess at a possible answer. This is before COTS became an
acronym. They felt they needed to record those tapes that way, and
they figured that reading them should be no big deal, even if existing
hardware didn't support it.

Another possible approach from the one described (which could
potentially lead to errors if data on the tapes was repetitious),
would be to connect two computers to the stream of data coming from
the tape drive, with them synchronously handing off the responsibility
for reading the data back and forth. I'm sure they could have thought
of that back then.

But they really shouldn't have used standard 9-track tape for this.
Something like DECtape, with random-access capabilities, would have
been more appropriate. Getting DEC to make a higher-performance
DECtape drive with vacuum columns may have been a problem, though.

John Savard