Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!ucsd!swrinde!cs.utexas.edu!uunet!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.misc Subject: Re: Educational Amigas Message-ID: <19211@cbmvax.commodore.com> Date: 22 Feb 91 01:54:54 GMT References: <884@caslon.cs.arizona.edu> <1991Feb16.215827.1@vax1.mankato.msus.edu> <1991Feb17.134709.12684@sugar.hackercorp.com> <1991Feb19.183108.26706@motaus.sps.mot.com> Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Distribution: usa Organization: Commodore, West Chester, PA Lines: 38 In article <1991Feb19.183108.26706@motaus.sps.mot.com> skipper@motaus.sps.mot.com (Skipper Smith) writes: >In article <1991Feb17.134709.12684@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes: >>Question. >>If you're planning on sticking an '040 card in your Amiga, then what difference >>does it make whether you bought a 3000/16 or a 3000/25? >>Peter da Silva. `-_-' >Bzzzzzt!!! (Did you really write this Peter?) The CPU slot is not designed to >remove the '030 from the system, therefore the motherboard still has to run >at the speed it was designed to run at- just in case somebody does a multi- >processor version of AmigaDOS, perhaps (I know, actually you should be using >the '030 as an I/O processor). Its up to the coprocessor card as to whether is wants to support use of the 68030 or not. If it does, it must clock the motherboard at its original speed. If not, it's possible for the coprocessor card to clock the motherboard at 25MHz. You have a choice of 16MHz or 25MHz, in any case; things like the memory controller can adjust for either speed, but not any arbitrary speed. >Also, there are a couple of parts on the 16 MHz mb that are spec'd at >16 MHz- they won't run at 25 MHz to further differentiate the two mb's >without making them too different. The 68881 and 68030, to be precise. The Amiga chips are all tested for 25MHz operation. You do have to change a few PCB jumpers to go add any coprocessor board, and a few more to go from 16MHz to 25MHz. Coprocessor boards that run at speeds other than 16MHz or 25MHz will use some kind of asynchronous interface anyway, kind of like in the A2630. Those will be much less likely to have a 25MHz clock around for motherboard speedups. >Skipper Smith | skipper@motaus.sps.mot.com -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "What works for me might work for you" -Jimmy Buffett