From mboxrd@z Thu Jan 1 00:00:00 1970 From: carl.lowenstein@gmail.com (Carl Lowenstein) Date: Mon, 20 Feb 2006 22:28:07 -0800 Subject: [TUHS] ATT 3b2 In-Reply-To: References: Message-ID: <5904d5730602202228o26dc9d68m6b302386b468d8ec@mail.gmail.com> On 2/20/06, 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