Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!asuvax!noao!arizona!sunquest!venus.sunquest.com!terry From: terry@venus.sunquest.com (Terry R. Friedrichsen) Newsgroups: comp.arch Subject: Re: Wanted DEC-10/20 stuff, and emulator Summary: DEC-10/TOPS-10 history and nostalgia Keywords: DEC-10 TOPS-10 DEC-10 TOPS-20 emulator Message-ID: <18030@sunquest.UUCP> Date: 22 Apr 91 20:25:30 GMT Sender: news@sunquest.UUCP Followup-To: comp.arch Distribution: usa Organization: Sunquest Information Systems, Tucson Lines: 86 uunet!dg!lewine writes: >jallen@eeserv1.ic.sunysb.edu (Joseph Allen) writes: >> Cool project! Maybe you can skip the extended address instructions (is that >> what you mean?), I don't think TOPS-20 used them (although I could be wrong >> about this). The byte instructions must be fun. > (1) TOPS-20 *does* make use of the extended addressing stuff. I > think that TOPS-10 does also. In any event, it is not that > difficult to include. I don't know of any compilers that > generate code that runs outside of section zero, but I have > not looked in a long time. TOPS-10 definitely did support the extended-address stuff, but not until one of the 7.0n releases, unless I am mistaken. And, of course, TOPS-10 continued to run on KA's and KI's, so the extended-address instructions would not be totally necessary for TOPS-10. When I finally left DEC-10 land (not without a great deal of regret), DEC had promised that the FORTRAN compiler would be able to generate non-section-0 code. > (2) The byte instructions are fairly easy. The biggest problem > is dealing with 36-bits on a machine that has 32-bit longs. I just wrote 'em the other day for my own emulator (which is in a fairly embryonic stage at this point). They were "fairly" easy, but definitely fun, as they were non-trivial due to the 32/36 bit stuff. I can't even force myself to THINK about 36-bit (or 71-bit - there's a trivia question for you) floating point; I would despair of ever getting the low-order bit EXACTLY right in all situations ... >> Once I heard a rumor that someone was going to put a DEC20 on a chip... >> anyone here about this? I have no other details. > No. I designed a one chip PDP-10 as a test for some CAD tools > and gate array technology. It was never built. I think I > still have the design someplace. Took me a whole weekend! That's very impressive. I considered building one out of bit-slice at one time, but this sounds like a far better deal. I'm surprised it went this quickly, especially with paging and the cache to do ... > The real questions is: would anyone want one badly enough to > to pay to get the gate array built? At one time, I'd have paid good money for a DEC-10 on my desk; but I'm addicted to Unix and superfast workstations now (though not without some (more) regret). > Also, DEC still has the > rights to the software and I don't think they are willing to > give it away. Worse, I hear that they are not even going to give the TOPS-20 sources to the customers they are abandoning. At least the TOPS-10 folks have sources and can do their own support. I can think of nothing but unprintable adjectives (complete with raising questions about their parentage) for the DEC folks who made THAT decision. >Anyway, I spent from about 1969-1980 building -10 software, hardware, >and microcode. I would love to see a PDP-10 emulator, but not enough >to do any work on it. I will be happy to answer questions on how the >machine, or Tops-10 or Tops-20 worked. I was a TOPS-10 hacker from 1976 to 1985; never did any hardware stuff beyond using a soldering iron on a KA-10 a few times. I am writing an emulator, mostly just for fun; I'm not really motivated enough to try to actually make the I/O work (or the floating-point, for that matter). But I also would be quite happy to entertain questions. >-------------------------------------------------------------------- >Donald A. Lewine (508) 870-9008 Voice >Data General Corporation (508) 366-0750 FAX >4400 Computer Drive. MS D112A >Westboro, MA 01580 U.S.A. > >uucp: uunet!dg!lewine Internet: lewine@cheshirecat.webo.dg.com Terry R. Friedrichsen terry@venus.sunquest.com (Internet) uunet!sunquest!terry (Usenet) terry@sds.sdsc.edu (alternate address; I live in Tucson) Quote: "Do, or do not. There is no 'try'." - Yoda, The Empire Strikes Back