Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!spool.mu.edu!caen!zaphod.mps.ohio-state.edu!hobbes.physics.uiowa.edu!news.iastate.edu!sharkey!aucis!zds-oem!easton From: easton@zds-oem.zds.com (Jeff Easton) Newsgroups: comp.sys.amiga.advocacy Subject: Re: (Video) Hardware Idiots ? Message-ID: <1991Jun14.013258.16010@zds-oem.zds.com> Date: 14 Jun 91 01:32:58 GMT References: <1991Jun12.232718.2373@mintaka.lcs.mit.edu> <22392@cbmvax.commodore.com> <1991Jun13.175041.15679@cs.mcgill.ca> Organization: Zenith Data Systems, OEM Systems Engineering Lines: 51 In article <1991Jun13.175041.15679@cs.mcgill.ca> tinyguy@cs.mcgill.ca (Yeo-Hoon BAE) writes: >In article <22392@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes: >>In article <1991Jun12.232718.2373@mintaka.lcs.mit.edu> rjc@geech.gnu.ai.mit.edu (Ray Cromwell) writes: >>>In article <22368@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes: >> >>> So the max transfer rate, with 0 wait states is 10mb/sec (theoretical) on >>>the fast ram bus at @25mhz. >> >>Well, that's to fast RAM, which actually does have wait states. You can't run >>zero wait states on a 25MHz 68030 using DRAM, at least not without extra magic. >> > > This is what I was puzzled for a while(still am). Why does 030 needs > MUCH faster DRAM to get it's 0 state, compare to 386? I know that on > 386(at least from it's manual), you can get a 0 w/s by using 80ns > interleaved memories. This was at 20MHz, ^^^^^ ^^^^^^^^^^^ The PC systems I've seen, generally at 20 Mhz w/ 80 nSec DRAM's you dont get true zero wait states (we are talking no cache here, right?). The best you can hope for is paging the memory and interleaving between banks if you have two consecutive banks of the same size memory. This isnt 0 ws, although most PC companies claim it is. Its usually on the average .7 ws, depending of course on what the CPU is doing. In the C&T NEAT chipset, you could not get 0ws w/ 80 nSec DRAM's at 16 Mhz. With the new SCATsx chipset, they optimised some things in the memory controller and now you get about the same memory performance at 20 Mhz that you got with the NEAT at 16 Mhz. Still not 0ws, but close. > but it seems that 20MHz 030 > won't go even close to achieving that! Am I mistaken? No, just confused by the PC marketing hype. > Are the 386 board > manufacturers not telling the truth? Some call it creative marketing :-) >| Yeo-Hoon Bae tinyguy@homer.cs.mcgill.ca | /// | Disclaimer: I dont work in marketing... Jeff Easton Zenith Data Systems // Systems Engineer \X/ easton%zds-oem@caspian.cs.andrews.edu easton@andrews.edu What? Preemptive Multitasking in only 256K of RAM? :^) :^)