Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!uunet!abvax!iccgcc.decnet.ab.com!herrickd
From: herrickd@iccgcc.decnet.ab.com
Newsgroups: comp.arch
Subject: Re: XDS940 computer
Message-ID: <1991Jun17.172202.4895@iccgcc.decnet.ab.com>
Date: 17 Jun 91 22:22:02 GMT
References: <1991Jun5.231450.25856@digi.lonestar.org> <13933@goofy.Apple.COM> <1915@tardis.Tymnet.COM>
Lines: 33

In article <1915@tardis.Tymnet.COM>, jms@tardis.Tymnet.COM (Joe Smith) writes:
> In article <13933@goofy.Apple.COM> johana!tsw@apple.com (Tom Watson) writes:
>>Yes, real old times, the SDS 940 (they were not sold after Xerox took over 
>>as far as I know).  Tymshare used a whole bunch of these.  At one time 
>>they had a whole bunch on a computer floor in Cupertino (over 20?).  Dial 
>>in ports came in from all over the country, and the networking was the 
>>beginning of Tymnet. 
> 
> At one time, TYMNET hosts 1 through 21 were all 940's.  (Hosts 22-39 were
> PDP-10's, and hosts 40-48 were IBM-370's.)  In 1986, all the 940's were
> shut down as Tymshare (at that point called "McDonnel Douglas Network
> Systems Company) moved their main Data Center from Cupertino to Fremont.

I spent five years with a company in Ann Arbor that bought 
a tremendous number of TRUs (Tymshare Resource Units) and sold
a larger number of CRUs.  The interactive product was written
in 940 assembly language.  Rumour had it that at one time they
had written a program and removed the comments from all the
sources for security reasons.

When a customer's usage got so high he didn't want to pay timesharing
fees, we would let him run it on his IBM mainframe.  There was a
940 simulator that ran the same code on the IBM as ran on the 940s.
There was a limited supply of 940s and we needed them for customers,
so the man who wrote the IBM simulator wrote microcode to add one
instruction to a Tymshare PDP-10 - be a 940 until you run into something
you can't handle.  Development moved to the ten.

I wonder if timesharing customers are still running on emulated 940s
on PDP-10s.  They were always working on the advanced version written
in Pascal.

dan herrick