Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!knuth!mjbtn!raider!elgamy!elg From: elg@elgamy.RAIDERNET.COM (Eric Lee Green) Newsgroups: comp.sys.amiga.advocacy Subject: Re: Computer Architecture question -- Daye Haynie Message-ID: <00673741923@elgamy.RAIDERNET.COM> Date: 8 May 91 22:32:03 GMT References: Organization: Eric's Amiga 2000 @ Home Lines: 35 From article , by melling@cs.psu.edu (Michael D Mellinger): > Can you just drop a 68040 into any computer and expect it to be as > fast as a computer designed around the 68040? Now, can you just drop Dave Haynie, in earlier postings, mentions that they would have had to go to 70ns DRAM's to drop a wait state from the memory. The problem was that at A3000 design time, 70ns DRAM's were considerably pricier than the ones they ended up using. In other words, the memory system is as fast as it can go while meeting a certain price point... designing-in a 68040 wouldn't have made any difference there. (This does imply that to get reasonable performance in a '040-based Amiga, it'd be wise to have some cache on board). If you're talking about the I/O bus, on the other hand, the I/O bus doesn't run at a constant clock rate. It goes however fast the expansion device can transfer data over it. Few expansion devices can shove 32-bit data at 25mhz, meaning that the /030/040 decision makes no difference as far as I/O speed goes. > an 88K processor in a computer that is based on the 68K and expect it > to work at all? The Amiga's Zorro III bus allows co-processors to jump on and off the bus independent of the main processor. It doesn't matter whether the co-processor is a 68K or 88K, as long as there's circuitry on-board to produce Zorro-style signals. It'd be quite easy to, e.g., run Unix on a Zorro III board packed with CPU and memory, which uses the Amiga for all its I/O. (Easy except for the space limitations of a Zorro III board... a Zorro slot is the same size as a ISA slot, meaning daughterboards, etc. would probably be necessary). -- Eric Lee Green (318) 984-1820 P.O. Box 92191 Lafayette, LA 70509 elg@elgamy.RAIDERNET.COM uunet!mjbtn!raider!elgamy!elg Looking for a job... tips, leads appreciated... inquire within...