From: lars@nocrew.org (Lars Brinkhoff)
Subject: [TUHS] [TUHS} PDP-11, Unix, octal?
Date: Wed, 18 Jan 2017 07:04:31 +0100 [thread overview]
Message-ID: <86lgu8rjio.fsf@molnjunk.nocrew.org> (raw)
In-Reply-To: <50a7fbcbb6af280eb108fff1361c37ee1718bff0@webmail.yaccman.com> (Steve Johnson's message of "Tue, 17 Jan 2017 19:06:28 -0800")
Steve Johnson wrote:
> Historical note: before networking, magnetic tapes were essential for
> backups and moving large quantities of data. Data was stored in
> magnetic dots running across the tape, and typically held a character
> plus a parity bit. Thus, there were 7-track drives for 6-bit machines,
> and 9-track drives for 8-bit machines. But nothing for 9-bit
> machines...
The 36-bit PDP-10 initially used 7-track drives, with six frames to a
word. During its lifetime sunset, 7-track drives were no longer made,
so 9-track drives were used instead. The most common encoding was to
store a word in five 8-bit frames, with four bits unused.
The PDP-10 did not have a fixed byte size. Were there any 9-bit
machines?
next prev parent reply other threads:[~2017-01-18 6:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-18 2:33 Noel Chiappa
2017-01-18 3:06 ` Steve Johnson
2017-01-18 3:36 ` Dan Cross
2017-01-18 6:53 ` Angelo Papenhoff
2017-01-18 7:31 ` ron minnich
2017-01-18 8:09 ` Angelo Papenhoff
2017-01-18 21:04 ` Steve Johnson
2017-01-18 21:42 ` Charles Anthony
2017-01-18 6:04 ` Lars Brinkhoff [this message]
2017-01-18 18:47 ` Peter Jeremy
2017-01-18 18:58 ` Charles Anthony
-- strict thread matches above, loose matches on Subject: below --
2017-01-18 14:28 Nelson H. F. Beebe
2017-01-17 2:23 Doug McIlroy
2017-01-18 16:47 ` Clem Cole
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