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From: John Levine <johnl@taugh.com>
Newsgroups: comp.arch
Subject: Re: wisdom of the ancients, was Architectural implications of locate mode I/O
Date: Wed, 3 Jul 2024 23:03:24 -0000 (UTC)
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According to MitchAlsup1 <mitchalsup@aol.com>:
>S.E.L created a thing they called the RCU (Remote Control Unit).
>It was basically a channel with writable microcode. NASA bought
>a bunch of them because they had tapes from the deep space radio
>telescopes where an entire 9-track tape contained 1 record. NASA
>just started the tape and recorded satellite data until the end
>of the tape, where they would start the next tape just before the
>end of the previous tape.
>
>So we programmed the RCU to read as much as the system memory
>allowed, backed the tap up 1 second while dumping the data to
>disk. Then we started the tape forward with the RCU watching
>the pattern on the tape, when it detected 4096 bytes of the
>last read, it would start streaming data in to memory again.
>
>No other company could demonstrate that they could read one
>of those tapes.
>
>Presto, reading a whole 9-track tape with no inter record gaps !!

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?

-- 
Regards,
John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly