Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!uupsi!ccavax!merriman From: merriman@ccavax.camb.com Newsgroups: comp.arch Subject: Re: why is 33 MHz a popular number? Message-ID: <37889.2753fde0@ccavax.camb.com> Date: 28 Nov 90 22:11:44 GMT References: <1990Nov27.192504.11191@ux1.cso.uiuc.edu> <1990Nov28.010513.17760@news.nd.edu> Organization: Cambridge Computer Associates, Inc. Lines: 31 In article <1990Nov28.010513.17760@news.nd.edu>, mahesh@caradhras.cc.nd.edu (Mahesh Subramanya) writes: > In article <1990Nov27.192504.11191@ux1.cso.uiuc.edu>, > shair@ux1.cso.uiuc.edu (Bob Shair) writes: >>The new IBM RISC 6000 model 550, at 41.6MHz or 24ns, may be >>something of an exception. I'll be interested to see whether >>anyone else uses that rate. > > From what I've heard, the reason behind that was that it was originally spec'd > at 40 Mhz, but they ran into some race conditions. So they basically tweaked > the clock around till the race cond. disappeared. The number *happened* to > be 41.6. Apart from the fact that 41.6 is my second favourite number (8-)), there > is nothing else really exceptional about it in terms of clock speeds. > -- I once heard the story that a particular, rather odd slow-speed asynch circuit bit rate (56.86 bps comes to mind) came to be because the designers were aiming for a somewhat higher speed, but found the mechanics in the printers could not keep up, so they selected the next set of gears from the Boston Gear catalog (or whatever) that would fit without too much rework, and what happened happened. > ************************************************************************ > Mahesh Subramanya INTERNET: mahesh@caradhras.cc.nd.edu > Senior Analyst > Office of University Computing NeXT: mahesh@numenor.next.nd.edu > University of Notre Dame Voice: (219) 239-5600 x6421 > Notre Dame, IN 46556 > ************************************************************************ George Merriman, Cambridge Computer Associates - New York