Re: [TUHS] AT&T Hardware

Re: [TUHS] AT&T Hardware

[Doug McIlroy]

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

Re: [TUHS] AT&T Hardware

[William Corcoran]

On my 3b2 310, you could always tell when the CPU were soaked at 100% utilization.  The main board would actually buzz. 

If you entered a CPU bound job with bc for example, you would know when the result was displayed on your terminal as the 3b2 would stop buzzing.  


Truly,

Bill Corcoran 

> On Jun 30, 2018, at 6:17 PM, Doug McIlroy <doug@cs.dartmouth.edu> wrote:
> 
> 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

Re: [TUHS] AT&T Hardware (3B2)

[Steve Johnson]

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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


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Re: [TUHS] AT&T Hardware (3B2)

[Lyndon Nerenberg]

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On Sun, 1 Jul 2018, Steve Johnson wrote:

> The 3B2 was designed for AT&T by Convergent Technologies. 

Really?

I think you are thinking of the PC[67]300?  Aka the 3B1?

The Convergent machines of the day were 68K based, and had nothing to do 
with any of the WE chips.

I sold/maintained Convergent gear for a few years before being hired into 
a shop that was inflicted with 3B2 hardware. Believe me, I know the 
difference between the two.

--lyndon

Re: [TUHS] AT&T Hardware (3B2)

[Kevin Bowling]

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