Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.tech Subject: Re: AmigaOS/UNIX - A Suggestion Message-ID: <15912@cbmvax.commodore.com> Date: 16 Nov 90 18:26:21 GMT References: <6653@chorus.fr> <6944@sugar.hackercorp.com> <8222@gollum.twg.com> <6998@sugar.hackercorp.com> <8284@gollum.twg.com> Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 45 In article <8284@gollum.twg.com> david@twg.com (David S. Herron) writes: >So to compare an Amiga with Unix to a '386 -- The A3000 has a much faster >bus (20 MByte/sec vs. ~1-3 MByte/sec; unless I get a Tyan machine but that >runs me $10,000). Some of the '386s these days are MCA or EISA based, either of which is in the same ballpark as the A3000 expansion bus. You do, in general, pay for it in those machines too. >The Amiga also has SCSI-II coming in at somewhere around 1MB/sec - 5 MB/sec >(depending on drive); what the speed of ESDI interfaces? That's actually SCSI-I running at those speeds. The SCSI-I limit is around 5MB/sec. Most drives don't go that fast, and for those that do, they don't go fast for long. The extra transfer speed of SCSI can really win for very high end drives, and for multiple drive systems. EDSI goes at about 1.5 MB/s, which is about the speed of the standard asynchronous SCSI transfer. What's really going to make a difference under UNIX is the multitasking performance of your hard disk, which most PClones don't address. Since the Amiga OS itself is multitasking, we tend to think in those terms from the ground up. The question you ask for determining multitasking hard disk performance is "how much CPU time is available when the hard disk controller is running full speed". For the A3000 and a 1.5 MB/s hard disk going full speed, you get about 96% of the CPU time for tasks that aren't disk bound. >Another consideration is hardware reliability. These 386 clones around >here simply haven't impressed me with their Solidness and Reliability... I'm sure the quality of the more established Clone vendors is up there with that of the Amiga. I'm equally sure that a good number of the cheaper ones aren't things I would feel safe investing in. Its apparently common practice at the bottom end to violate timing parameters and other specs in the design to eek out a bit more performance performance, at least in a cool room, for the same price. As a computer designer, I get real nervous when I see timing specs violated -- that's just plain begging for trouble. ><- David Herron, an MMDF & WIN/MHS guy, -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Standing on the shoulders of giants leaves me cold -REM