Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!max!crisp From: crisp@mips.COM (Richard Crisp) Newsgroups: comp.arch Subject: Re: Tektronix shutdown & move away from 88k's?? Message-ID: <42572@mips.mips.COM> Date: 31 Oct 90 06:54:26 GMT References: <1536@ftc.framentec.fr> <1990Oct19.120218.9450@canterbury.ac.nz> <15497@hydra.gatech.EDU> <2176@lupine.NCD.COM> <42310@mips.mips.COM> <42488@mips.mips.COM> Sender: news@mips.COM Reply-To: crisp@mips.COM (Richard Crisp) Organization: MIPS Computer Systems, Inc. Lines: 45 In article pcg@cs.aber.ac.uk (Piercarlo Grandi) writes: > >crisp> I also remember back in 1978 or 1979 that Byte stated that >crisp> Motorola would offer a version of the 68000 that had the >crisp> microcode in EPROM so that users could re-microprogram it for >crisp> whatever instruction set they wanted! > >Haha. This piece of news at least was factually true. If you ordered >enough of them you could ask Motorola to change the onchip microcode ROM >mask for the 68k. I seem to remember that there were other cases, but >the well known one was IBM, who actually reprogrammed the 68k to emulate >a subset of the 370 architecture, and was able to run VM/370 on it (with >some effort). The oddest thing was that the 370/68k was actually a >coprocessor in a revamped IBM PC, alongside an 8088. Ah wonders of >technology. > Perhaps I missed something, but I see no evidence of the factuality of Byte's assertions in the above statement. I mentioned EPROM implemented microcode store, Mr. Grandi has said nothing to support his assertion that Byte's claims were true. All that has been offered as evidence was the fact that IBM had a custom derivative of the 68K built by Motorola. As I mentioned earlier, more than the microcode was changed, the "core" or execution unit was also changed in order to support IBM's requirements. In fact there were two chips that were part of this program, one called the "Cascadilla Minor" and the other called the "Cascadilla Major". The suffixes reflected the level of deviation from the original 68K design. I seem to remember that it took two "minors" and one "major" to implement the module mentioned above. Let's remember what the original thread was about: The trade rags oftentimes hear of rumors and publish factually incorrect stories. Just like the errors made in newspapers, magazines and television (remember the recent case where "20/20" featured a story about the man who played "Buckwheat" in the Our Gang show? Well it turned out that Buckwheat had been dead for 10 years and the man featured on the show was an imposter!), our lovable trade rags aren't infallible. The prudent reader will take rumors as just that. -- Richard Crisp crisp@mips.com MIPS Computer Systems !decwrl!mips!crisp 928 Arques MS 2-02 (408) 524-8177 Sunnyvale, Ca 94086