Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!lll-lcc!ames!oliveb!sun!pepper!cmcmanis From: cmcmanis@pepper.UUCP Newsgroups: comp.sys.atari.st Subject: Re: More ST Floating Point Performance Message-ID: <21106@sun.uucp> Date: Mon, 15-Jun-87 15:00:05 EDT Article-I.D.: sun.21106 Posted: Mon Jun 15 15:00:05 1987 Date-Received: Wed, 17-Jun-87 01:45:20 EDT References: <8706120032.AA13145@cory.Berkeley.EDU> <1361@batcomputer.tn.cornell.edu> Sender: news@sun.uucp Reply-To: cmcmanis@sun.UUCP (Chuck McManis) Organization: Sun Microsystems, Mountain View Lines: 42 In article <1361@batcomputer.tn.cornell.edu> (braner) writes: >As far as I know, the Amiga does not "support" the 68881 in any way >beyond providing an expansion slot. The 68881 is really only fully >supported by the 68020 CPU chip. The "Turbo Amiga" is basically a >seperate computer that uses the Amiga as sort of a terminal. It has >its own CPU, memory. And it costs a lot more than the Amiga itself. >The Mac II is comparable in price and comes standard with the 68020/ >68881. These two machines may seem expensive to us Atari users, but >they are _incredibly_ powerful for number crunching. Better than the >VAX and for a small fraction of the price... Where are you, Atari? >(Working on a new 8/16 bit machine, I believe.) A small clarification here, the Amiga 'supports' the 68881 insomuch that it knows to save it's context on task switches, and there are some resident libraries that use it, thus if your program currently calls routines in the library mathieee.library then when that library is replaced with the one that uses the 68881 your program automagically speeds up. But if it is a '000 or '010 processor the speed ups are mostly in the trancendental functions, not your basic multiply and divide. Secondly, the 'Turbo' Amiga does not use the Amiga as a 'terminal', the 68020 removes the 68000 from the bus by asserting a line on the expansion connector (or on a daughter board). The 68020 boots from the Kickstart just like the 68000 would have if it had control of the bus. The Turbo Tower from CSA associates is an expansion box that also contains a 32 bit memory buss. Anyway, you get the idea, it isn't anything like the proposed 'TT'. This is not to say it is good or bad either since there are benefits either way. >The Motorola FFP library (and all other 32-bit FP libs) do _NOT_ have >10-digit precision, only about 6--7 digits. That is frequently useful >but just as frequently terrible. Think about it: 10^10 ~ 2^33, so >no bits left for the exponent... >- Moshe Braner So true, at a conference once I asked the Motorola Rep what they used FFP for. He replied "I think Tiny Basic uses it." Ask yourself, do you want to use a format that has less precision than a $5 calculator? --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.