Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!compass!worley From: worley@compass.com (Dale Worley) Newsgroups: comp.lang.c Subject: Re: Can analysis detect undefined expressions? Message-ID: Date: 26 Jun 91 15:35:41 GMT References: <14816.28673F12@stjhmc.fidonet.org> Sender: root@compass.com Distribution: world Organization: Compass, Inc., Wakefield, MA, U.S.A. Lines: 17 In-reply-to: Dave.Harris@f14.n15.z1.fidonet.org's message of 25 Jun 91 12:59:52 GMT In article <14816.28673F12@stjhmc.fidonet.org> Dave.Harris@f14.n15.z1.fidonet.org (Dave Harris) writes: Are the electronics such that the same memory address can really be written to similtaneously? If so would you expect a completely random result or something in the range of 1 to 7? On the Connection Machine, if you are using the message-passing system to perform the store, stores that collide will be merged by (1) adding, (2) or-ing, (3) and-ing, (4) max-ing, (5) min-ing, or (6) picking a random one. It all depends on how you set some flag in the message-passing system. It is quite conceivable that there are parallel processors where colliding writes produce completely random results, if it saves a few nanoseconds somewhere... Dale Worley Compass, Inc. worley@compass.com -- Our informal mission is to improve the love life of operators worldwide. -- Peter Behrendt, president of Exabyte. Quoted in Digital Review, Feb 4, 1991.