Xref: utzoo alt.folklore.computers:12572 comp.arch:23136 Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!apple!johana!tsw@apple.com From: johana!tsw@apple.com (Tom Watson) Newsgroups: alt.folklore.computers,comp.arch Subject: Re: XDS940 computer (or Xerox Sigma 9) Message-ID: <13933@goofy.Apple.COM> Date: 7 Jun 91 17:35:20 GMT References: <1991Jun5.231450.25856@digi.lonestar.org> Sender: usenet@Apple.COM Organization: Personal Lines: 87 Charles Richmond (crichmon@digi.lonestar.org) writes: >A friend of mine in college told me about the Sigma 9 computer >that he used at his previous university. He said it was great >for interactive use. I believe that the computer was designed >by Scientific Data Systems (SDS). Later this company sold >out to Xerox and became Xerox Data Systems (XDS). I would >like to know more about the hardware and software of the Sigma 9 >and perhaps its sibling, the Sigma 7. Particularly: > > 1) How many registers did the machines have, and did any > have special uses? The machine has 16 general registers, registers 1-7 were used as index registers. Instructions addressed bytes, halfwords (16 bits), words (32 bits), and doublewords (64 bits). Included stack instructions that used a stack descriptor (multiple stacks). > 2) What was the instruction set like? (Maybe someone has > a reference card or such and can provide a complete > list of the numeric opcodes) The instruction set was fairly complete, it was ment to compete with the IBM 360 series, and even used EBCDIC (good, or bad depending upon how you looked at it). The Sigma 9 even has an instruction called edit byte string which is almost a 'printf' in an instruction. > 3) Was this a 32-bit machine? Yes, the registers had 32 bits. If operands were 64 bits, you used register pairs. Halfwords (16 bits) were automatically sign extended when loaded into registers. Bytes were treated as unsigned things and the upper 24 bits were set to zero when loaded into registers. > 4) What high level languages were available for these machines? Several languages were available, most commonly used was Fortran (looking at the listing of the compiler was an experience in itself :-) In addition, there was an Algol-68 compiler, APL, At least 3 assemblers (most subsets of the largest one), and some utilities like pip (it was called PCL). > 5) What operating system was used and how does it compare to > current systems such as Unix? Two main operating systems existed (CP-R, and CP-5) The first (CP-R) was a smaller real-time monitor that could be used for process control and the like. The larger one (CP-5) was a really neat operating system, it could do almost everything, batch, timesharing, real-time, transaction processing, and remote-batch processing (thus the '5'). One of its later features was the addition (this was back in 1973/4) of a second processor to take over some of the load. I was told that the addition of the second processor code was very minimal (1000 lines is a number that sticks to mind). > 6) What technology was used in the hardware? (IC's, transistors, > tubes, TTL, RTL, etc.) The original design dates back to 1965 (early Sigma machines (Sigma 2, 5, and 7) and used 4 volt DTL logic. To get the speed, outputs were pulled up to 8 volts and clamped at 4. Most of the logic cards were integretated output stages with descrete diode input trees. > 7) Any interesting stories related to these machines? The Robin-Hood/Friar Tuck story comes to mind, discussed here earlier. > 8) Does anyone still use these machines, or clones of them? I think some people still do, but I'm not sure. The division of Xerox was sold (given away, take your pick) to Honeywell back in the 1975 time frame. It was a shame, nice company to do business with. As for clone makers, a company called Telefile (which started out making compatable add-on hardware) had a clone operational, its success is unknown to me. > 9) Where would one go to find hardware manuals or even junked > machines of this family? I still have a Sigma 5 CPU manual (that's the machine I worked on) and remember it well. > >According to Steven Levy in the book _Hackers_, Peter Deutsch >did an operating system for the XDS940 that Community Memory used >in San Francisco in the 70's. This machine was used as a means >of communication, for people with like ideas or things to sell. >Are you still out there, Mr. Deutsch? I remember seeing some >postings on the net from you. Maybe you can take time to fill >in the details of the XDS940. 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. The 940 had two arithmetic registers, one index register (24 bits here), and 32k words of user CORE. It was a modification of the SDS930 and the start of the modification was done at Berkeley (UCB) in the early 1960's. The basic construction of this machine was descrete transistor logic (2nd generation machine). Both machines very interesting... ----- Just somebody in Sillycon Valley. No, I don't play golf, or run a big blue company.