Xref: utzoo comp.arch:22808 comp.unix.ultrix:7286 Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!mips!mash From: mash@mips.com (John Mashey) Newsgroups: comp.arch,comp.unix.ultrix Subject: Re: ACE, buses, and the future of ultrix Message-ID: <3683@spim.mips.COM> Date: 20 May 91 19:13:07 GMT References: <281f3e99.2f35@petunia.CalPoly.EDU> <1991May2.224316.17903@ico.isc.com> <816@cadlab.sublink.ORG> Sender: news@mips.COM Followup-To: comp.arch Organization: MIPS Computer Systems, Inc. Lines: 37 Nntp-Posting-Host: winchester.mips.com In article <816@cadlab.sublink.ORG> martelli@cadlab.sublink.ORG (Alex Martelli) writes: > ... >:for OS software that has yet to be written, why did they need to pick two >:directions (times two hardware directions gives four?) instead of one? I >:may be missing something important, but this aspect of ACE sure looks like >:one of those "it's a dessert topping; it's a floor polish" skits. > >Don't forget they'll support BOTH Dec Turbochannel AND EISA... so, times >two again... the bus variation may be the most important of the three, for >3rd party addon-board manufacturers, and for purchasers of vast numbers of >machines, who can't really buy machines with different buses if they want >to be able to minimize spare parts inventory for the addon cards. This is nonsense. In the PC world: there are XT busses, AT busses, EISA busses, MCA busses. Much of this happened sort of by accident, and a lot of software knows too much about what's there, in gory detail. ACE assumes that ability to hit different price/performance areas, and to evolve, requires a sensible scheme for the inclusion of different busses, (or no bus at all), which after all, is done by most serious computer systems vendors. It is absolutely nuts to think that a bus in widespread use now [EISA, for example] is going to fulfill everybody's needs in 10 years. Hence, the ACE compatibility specifications are structured so that one can have a reasonable shrink-wrapped kernel that doesn't HAVE to know about the I/O bus choice, but still has enough info to be able to boot. This is a lot easier to do when starting from scratch with the experience of the last 10 years.... -- -john mashey DISCLAIMER: UUCP: mash@mips.com OR {ames,decwrl,prls,pyramid}!mips!mash DDD: 408-524-7015, 524-8253 or (main number) 408-720-1700 USPS: MIPS Computer Systems MS 1/05, 930 E. Arques, Sunnyvale, CA 94088-3650