Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!samsung!xylogics!world!bzs From: bzs@world.std.com (Barry Shein) Newsgroups: comp.arch Subject: Re: Yet Another Upgrade Anecdote Message-ID: Date: 3 May 90 00:26:31 GMT References: <43777@iuvax.cs.indiana.edu> <1161.263f4987@gp.govt.nz> Sender: bzs@world.std.com (Barry Shein) Organization: The World Lines: 37 In-Reply-To: don@gp.govt.nz's message of 2 May 90 09:35:33 GMT >I seem to recall a rumour floating around a few years ago, that a VAX >11/750 could be sped up by a factor of four by changing a couple of >resistors. It sounds rather unlikely, but the story went it couldn't be >faster than the 11/780 that since the machine was to be a low-end one and >cheaper; this being despite the somewhat better technology involved. The way I heard it at the time was that a group in England had sped up a 750 somewhat (I doubt it was 4X, more like 1.25X) by removing noops from the microcode (and, of course, the apocryphal "if you do this DEC won't service the machine anymore", probably true.) I'm fairly sure this did exist and remember looking into it at the time, something about their changes made the machine hang regularly, so you tooks your chances. Didn't sound worthwhile to me and maybe that's where it died, the speedup wasn't that great and the cost was. 750's were usually time-sharing machines, so reliability was a big issue. Now, how about the story about a certain well known defense contractor back in the hey-days of the Microvax-II (about .9MIPS, or 1MVUP :-) with their own silicon implementation that ran at 7 MIPS. But DEC refusing to buy back the design (supposedly) because it was too difficult (costly) to verify that their implementation really worked. Perhaps this belongs in alt.folklore.computers, although the person that told me that last story had just come back from playing with one, all excited (ca. 1987). So not really urban mythology, unless he was just plain lying, I tend to doubt it. I could name the company, tho I doubt they would appreciate it (why? who the hell knows, people are like that.) -- -Barry Shein Software Tool & Die | {xylogics,uunet}!world!bzs | bzs@world.std.com Purveyors to the Trade | Voice: 617-739-0202 | Login: 617-739-WRLD