From: Kevin Bowling <kevin.bowling@kev009.com>
To: Steve Johnson <scj@yaccman.com>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>,
Doug McIlroy <doug@cs.dartmouth.edu>
Subject: Re: [TUHS] AT&T Hardware (3B2)
Date: Mon, 2 Jul 2018 02:56:33 -0700 [thread overview]
Message-ID: <CAK7dMtDasK0-D2PX8kCL1iAJEP8pyd31868W3KjBXfR73h0ujg@mail.gmail.com> (raw)
In-Reply-To: <285b5c9f6210cfbc4f2ff3a84c11e674cc230879@webmail.yaccman.com>
I have several working 3B2s and a non-working 3B1 aka UNIX PC/ 7300.
Your story sounds more like a 3B1 where Convergent Technologies was
the ODM (original design mfg). I've seen Convergent branded 7300s in
collections or for sale.
The various 3b2 models are a relatively simple backplane design, the
cards are all discrete chips on small boards that aren't very dense
integration vs other contemporary systems. I couldn't see more than a
few manual reworks being more cost effective than reving the PCBs on
it, especially because it was a "serious system".
Wikimedia has a good pic of the first model, 3B2-300, main board
https://upload.wikimedia.org/wikipedia/commons/3/3d/3b2-300-motherboard.jpg
One thing I've desired are contemporary pictures of the 3B5, 3B15 and
3B20 if anyone knows of intact machines.
On Sun, Jul 1, 2018 at 6:29 AM, Steve Johnson <scj@yaccman.com> wrote:
> The 3B2 was designed for AT&T by Convergent Technologies. I later worked
> with several people at Convergent, one of whom had a framed circuit board on
> his wall. It was a wonder to behold -- the board had wires all over it that
> were added later, and nearly a dozen "bugs" -- in the days of discrete logic
> chips, a bug was when you took another chip and glued it, upside down, on
> top of an existing chip and then ran wires to the pins in the air. As I
> recall, the story was that the first demo of the 3B2 happened roughly six
> weeks after the initial request, using the board on the wall. Now, that's
> what should really be in the computer museums...
>
> In those days, if there was floating point it was a separate chip, and the
> 3B2 had none. Floating-point instructions caused a fault, which meant a
> context switch to the OS, where the instruction was emulated and then the
> program returned. The performance, as I recall was about 800 FLOPS -
> dismal. We fixed the compiler so it would generate calls to subroutines
> that did the floating point operations, and the performance improved by over
> an order of magnitude -- still dismal, but no longer ridiculous...
>
> One of the events that led me to leave AT&T was that they fired the head of
> the benchmarking group at Indian Hill, a most competent woman, because they
> didn't like the results she was presenting. When a company's information
> channels stop functioning reliably, it's time to leave...
>
> Steve
>
>
>
> ----- Original Message -----
> From:
> "Doug McIlroy" <doug@cs.dartmouth.edu>
>
> To:
> <tuhs@tuhs.org>
> Cc:
>
> Sent:
> Sat, 30 Jun 2018 14:24:24 -0400
> Subject:
> Re: [TUHS] AT&T Hardware
>
>
> Anent 3B's: Last time I visited Paul Allen's Living Computer Museum
> the only working Unix on display was running on a 3B2. Apparently
> the machine was robust if nothing else.
>
> doug
prev parent reply other threads:[~2018-07-02 9:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-30 18:24 [TUHS] AT&T Hardware Doug McIlroy
2018-07-01 1:05 ` William Corcoran
2018-07-01 13:29 ` [TUHS] AT&T Hardware (3B2) Steve Johnson
2018-07-02 0:12 ` Lyndon Nerenberg
2018-07-02 9:56 ` Kevin Bowling [this message]
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