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From: Clem Cole <clemc@ccc.com>
To: Dave Horsfall <dave@horsfall.org>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] dmr streams & networking [was: Re: If not Linux, then what?]
Date: Sat, 31 Aug 2019 15:03:46 -0400
Message-ID: <CAC20D2MdDGGZ9Ex1k8vTifZUEKxk+dt+NcUeYm8HkPQMKpnAvA@mail.gmail.com> (raw)
In-Reply-To: <alpine.BSF.2.21.9999.1908311531460.37360@aneurin.horsfall.org>

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On Sat, Aug 31, 2019 at 1:38 AM Dave Horsfall <dave@horsfall.org> wrote:

> Yep, that certainly rings a bell.  ISTR that Sun had a board with the two
> CPUs, one keeping an eye on the other.

Interesting, I was under the belief that Sun never even tried the trick (at
least as a product).  The original Stanford University Network (SUN) CPU
was built for an Intel Multibus (electrically and mechanically) but using a
single 68000 instead of an Intel processor.  The 'SUN' was designed by one
of Forest's graduate students (Andy Bechtolsheim
<https://en.wikipedia.org/wiki/Andy_Bechtolsheim>); and the University licensed
the design extremely cheaply throughout the valley (VLSI Tech, *a.k.a.* Sun
Microsystems, was only one of the licensees.  But for instance the original
Cisco AGS and the Imagen Laser printers both used CPU's licensed from the
Unversity).

FWIW: I knew Andy at CMU previously, he had designed a similar board for
the CMU front-end as I was leaving for Tektronix - when I was there we used
LSI-11s and Andy replaced that with an 8085 (then 8086) based Multibus
[IIRC, Phil Karn may have mixed up in all that too - he was hacking on what
would become KA9Q TCP on his Z80 and then the 8085.   We had all taken the
graduate realtime course from Steely Dan as lab partners and our big
project was based on hacks to that hardware].

That said, it was Forest that proposed the executor/fixer trick (as I say
he gave a paper at an Asilomar Microprocessor Conference which I have sadly
misplaced).   It is certainly possible that Andy tried building it, but the
only two firms that I know of that built processors using the idea were
Apollo and Masscomp (neither who used or licensed the SUN CPU design from
Stanford) although all of them used a flavor of the Multibus as their first
bus.

I don't know what Apollo did. The multibus mechanically had two connectors,
but the Intel-defined I/O bus was on the lower (larger connector).   At,
Masscomp the MC-500 a private (synchronous) memory bus, that was very
similar to the BI in its protocol (because Dave designed both of course).
It was built on the unused/undefined header and ran much faster than the
I/O bus since memory fetches occurred.  Also, the Masscomp >>card cage<<
was larger than Multibus (I think Apollo was also).   The shorter boards
fit into the backplane, the larger size allowed for more 'chips to fit.'
IIRC, with the original memory chips being used at the time, one reason why
the Masscomp was so much faster than the Sun-1 (and 2) was it had larger
memory capacity on its boards and the memory transaction were quicker.

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  reply	other threads:[~2019-08-31 19:04 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30 20:21 Norman Wilson
2019-08-30 20:28 ` Larry McVoy
2019-08-30 20:39 ` Clem Cole
2019-08-30 21:52   ` Larry McVoy
2019-08-31  0:58     ` Clem Cole
2019-08-31  1:13       ` Bakul Shah
2019-08-31  2:46         ` Clem cole
2019-08-31  2:57           ` Clem cole
2019-08-31  3:14             ` Gregg Levine
2019-08-31  3:47               ` Clem cole
2019-08-31  3:38             ` Bakul Shah
2019-08-31  5:37             ` Dave Horsfall
2019-08-31 19:03               ` Clem Cole [this message]
2019-09-05  5:11                 ` Al Kossow
2019-09-02  8:28               ` Peter Jeremy
2019-09-02 23:26                 ` Dave Horsfall
2019-08-31  3:19           ` Bakul Shah
  -- strict thread matches above, loose matches on Subject: below --
2019-09-01  2:36 [TUHS] dmr streams & networking [was: Re: If not Linux, then what? Rudi Blom
2019-09-01  2:16 [TUHS] dmr streams & networking [was: Re: If not Linux, then what?] Rudi Blom
2019-08-31  9:43 Rudi Blom
2019-08-31 15:41 ` Clem Cole
2019-08-28 18:41 Doug McIlroy
2019-08-28 18:49 ` arnold
2019-08-28 19:03   ` Chet Ramey
2019-08-28 19:05     ` Larry McVoy
2019-08-29 14:58       ` Jason Stevens
2019-08-29 16:25         ` arnold
2019-08-29 16:38           ` Ralph Corderoy
2019-08-29 17:35             ` arnold
2019-08-28 21:55 ` Rob Pike
2019-08-28 22:29   ` George Michaelson
2019-08-28 22:36     ` William Pechter
2019-08-28 23:02       ` Arthur Krewat
2019-08-29  0:11       ` Clem cole
2019-08-29  0:18         ` George Michaelson
2019-08-29  6:27         ` Lars Brinkhoff
2019-08-28 17:57 Doug McIlroy
2019-08-28 18:05 ` Adam Thornton
2019-08-28 18:08 ` arnold
2019-08-28 18:27 ` Warner Losh
2019-08-28 18:34   ` Warner Losh
2019-08-28 21:54 ` Rob Pike
2019-08-29  6:43   ` arnold
2019-08-29  7:39     ` Rob Pike
2019-08-29 16:26       ` arnold
2019-08-29  3:29 ` Lawrence Stewart
2019-08-29  4:10   ` Larry McVoy
2019-08-28  9:17 Paul Ruizendaal
2019-08-28 10:44 ` Angelo Papenhoff

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