[TUHS] re: ATT 3b2

[TUHS] re: ATT 3b2

[dmr]

 > I'm interested in acquring an AT&T 3b2 computer.  One of these systems
 > used to run a famous public UNIX system "killer".  They also run #5ess
 > telephone switches, however the OS is different in that case
 > (DMERT/UNIX-RTR instead of whatever the consumer-level 3b2 runs).

 > If anyone has information on where to acquire these (I saw the recent
 > discussion on 3b1s and I know they are more prolific than 3b2s-- infact
 > a friend of mine used to have a UNIX PC which we set up a BBS on).

The 3B2 was not the same machine as the one in 5ESS, which
was/is the 3B20D, a fairly large duplexed machine (two processors
that mutually checked each other).  The 3B2 was a desktop.
The 3B20D wasn't sold commercially, as far as I know.  There
was a 3B20S (multi-cabinet) that at least nominally
was commercially available.

Their ISAs were not quite the same, but some assembler language
tricks made the assembler-level languages look quite similar.

	Dennis

[TUHS] ATT 3b2

[Corey Lindsly]

> The 3B2 was not the same machine as the one in 5ESS, which
> was/is the 3B20D, a fairly large duplexed machine (two processors
> that mutually checked each other).  The 3B2 was a desktop.
> The 3B20D wasn't sold commercially, as far as I know.  There
> was a 3B20S (multi-cabinet) that at least nominally
> was commercially available.

In '93 or '94 I responded to an advertisement by
Temple University (Philadelphia) that they were
giving away for free - U haul - a working 3B20S
system. Figuring it was simply a slightly bigger 
brother of the 3B2, I arranged to pick it up and
drove out there. 

Imagine my dismay when I discovered it to consist
of four refrigerator-sized cabinets, several
washing-machine disk units, and boxes of spare
parts. Alas, no way that was all going to fit
in my little apartment, not to mention the power
requirements, so I had to turn it down. I hope
they eventually found a good home for it..

Regards,

---corey

[TUHS] ATT 3b2

[Carl Lowenstein]

On 2/20/06, dmr at plan9.bell-labs.com <dmr at plan9.bell-labs.com> wrote:
>  > I'm interested in acquring an AT&T 3b2 computer.  One of these systems
>  > used to run a famous public UNIX system "killer".  They also run #5ess
>  > telephone switches, however the OS is different in that case
>  > (DMERT/UNIX-RTR instead of whatever the consumer-level 3b2 runs).
>
>  > If anyone has information on where to acquire these (I saw the recent
>  > discussion on 3b1s and I know they are more prolific than 3b2s-- infact
>  > a friend of mine used to have a UNIX PC which we set up a BBS on).
>
> The 3B2 was not the same machine as the one in 5ESS, which
> was/is the 3B20D, a fairly large duplexed machine (two processors
> that mutually checked each other).  The 3B2 was a desktop.
> The 3B20D wasn't sold commercially, as far as I know.  There
> was a 3B20S (multi-cabinet) that at least nominally
> was commercially available.
>
> Their ISAs were not quite the same, but some assembler language
> tricks made the assembler-level languages look quite similar.

Here at U.C. San Diego, the Electrical Engineering and Computer
Science department  received an AT&T donation of a whole lab full of
3B2 computers for instructional purposes.

I had the unenviable task of trying to teach a course based around
Assembly language and interfacing to higher-level languages (like C)
and OS functionality.  Using the 3B2, for which the official AT&T
position was that these computers were not intended to be programmed
in assembly language, and the appropriate documentation was sort of
non-existent to us outsiders.

I remember when I discovered that the assembler would generate
instructions different from those that were present in the source
code, as demonstrated by running the object-code disassembler.

    carl
--
    carl lowenstein         marine physical lab     u.c. san diego
                                                 clowenst at ucsd.edu

[TUHS] ATT 3b2

[Michael Davidson]

dmr at plan9.bell-labs.com wrote:

>The 3B2 was not the same machine as the one in 5ESS, which
>was/is the 3B20D, a fairly large duplexed machine (two processors
>that mutually checked each other).  The 3B2 was a desktop.
>The 3B20D wasn't sold commercially, as far as I know.  There
>was a 3B20S (multi-cabinet) that at least nominally
>was commercially available.
>
>Their ISAs were not quite the same, but some assembler language
>tricks made the assembler-level languages look quite similar.
>  
>
That brings back memories ...

If I remember correctly, all of the "real" members of the 3B family
(i.e. 3B2, 3B5, 3B15 and 3B20) shared a common "virtual"
instruction set called (I think) IS25 - it was the job of the assembler
to translate IS25 into the actual machine code for the specific
processor used in each machine.

IS25 was a little curious because it only defined those instructions
that were likely to be of use to the C compiler - thus there was a
"push" instruction so that the compiler could push function arguments
onto the stack, but no "pop" instruction because the C compiler
never generated it.

The 3B2 was also quite "ahead of it's time" in having a soft power
switch (i.e. one that signalled the sytem to shut down and power
off rather than simply cutting the power) and the ability to (attempt
to) reconfigure itself when new hardware was installed. This latter
feature involved automatically relinking the kernel and rebooting
the system and it was not uncommon to get into an infinite loop
where, each time the system booted, it decided that the current
system configuration didn't quite match the booted kernel and
proceeded to relink yet another kernel and reboot.