Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!uupsi!sunic!news.funet.fi!tukki.jyu.fi!jyu.fi!otto From: otto@tukki.jyu.fi (Otto J. Makela) Newsgroups: sci.electronics Subject: Re: 80386. Message-ID: Date: 31 Dec 90 03:02:33 GMT References: <1990Dec18.234020.2491@uoft02.utoledo.edu> <1990Dec28.210731.10685@zoo.toronto.edu> Sender: news@tukki.jyu.fi (News articles) Organization: Turing Police, Criminal AI section Lines: 38 In-Reply-To: henry@zoo.toronto.edu's message of 28 Dec 90 21:07:31 GMT Nntp-Posting-Host: jyu.fi In article <1990Dec28.210731.10685@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: In article <1990Dec18.234020.2491@uoft02.utoledo.edu> stx0641@uoft02.utoledo.edu writes: > My friend told me that we can use 16Mhz 80386 DX CPU on 25Mhz 80386 DX >motherboard. Is it reliable? Will it destroyed chips on the motherboard? It is unlikely to do any damage. But it will not be reliable. Chips will often run faster than their rated speed, when the temperature and the power voltage and the surrounding circuitry and the phase of the moon are all just right. But there is no way to tell whether the chip is just barely working, so that the slightest change in conditions will start producing intermittent random failures. Actually, if it boots, it'll probably be (reasonably) reliable. The 80386 is such a complicated beastie that if it's even slightly flaky, it'll probably crash immediately. It'll probably run hotter 'en 'ell, though. Now, the problem with Taiwanese 25MHz boards that are built with 20MHz chips is that since the support chips (you know, like the ones that C&T makes) are also rated for the lower speed, all the timings are screwed up. It won't mean much if you only use a ST-506 hard disk, but you probably won't get an Adaptec SCSI to run, since they try to use the bus to a maximum efficiency ! Also, I've seen several IDE hard disks which intermittently scrambled the data they were reading/writing, when run on a cheapo 25MHz machine. No, they didn't give a CRC error or anything, they screwed up on the data bus side. This is again easy to ignore on a low-tech operating system like DOS, where you'll notice the problem only when your FAT gets hit, but Unix won't even get halfway up on machines like this. Caveat Emptor! "I've seen things... you people couldn't imagine. Attack ships on fire off the shoulders of Orion. I've watched C-beams glitter in the dark near the Tannhauser gates. All those moments will be lost... like tears in the rain." -- /* * * Otto J. Makela * * * * * * * * * * * * * * * * * * */ /* Phone: +358 41 613 847, BBS: +358 41 211 562 (CCITT, Bell 24/12/300) */ /* Mail: Kauppakatu 1 B 18, SF-40100 Jyvaskyla, Finland, EUROPE */ /* * * Computers Rule 01001111 01001011 * * * * * * * * * * * * * * * * */