Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!rice!uupsi!sunic!cs.umu.se!dvljhg From: dvljhg@cs.umu.se (J|rgen Holmberg) Newsgroups: comp.sys.amiga.advocacy Subject: Re: Blitter vs. 040 (was: Computer Architecture question Message-ID: <1991May13.015053.11150@cs.umu.se> Date: 13 May 91 01:50:53 GMT References: Sender: news@cs.umu.se (News Administrator) Organization: Dep. of Info.Proc, Umea Univ., Sweden Lines: 42 In article melling@cs.psu.edu (Michael D Mellinger) writes: > >In article mykes@amiga0.SF-Bay.ORG (Mike Schwartz) writes: > > The blitter provides parallel computing power. You can decide whether to > use the 68040's cycles to render graphics or to do heavy calcuations, whichever > the application requires. Another way to describe how this works: > > The blitter has a shared bus with the CPU. The CPU has 3 buses (at least on > an A2500) - CHIP (shared with blitter), ZORRO (slots), and FAST memory bus. > While the Blitter blits, the CPU can be accessing either of the other 2 buses > to its heart's content. > >How fast are the Amiga buses? If you use the 040 to render graphics, >it must access the chip RAM correct? So there will be bus contention? >Wouldn't it be better to let the 68040 just have the bus? Yes, of course it would be better. If you want to do some serious calculations at the same time you could have the CPU working in fast RAM and the blitter could do the actual display without loosing any CPU power whatsoever. >How much >memory does video RAM take up in the 680x400(4096 colors) graphics >mode or a better graphics mode. 680? 640x400x6/8 bytes I would think. >When you fill up chip RAM you have a >problem. Do all the current Amiga's ship with the 2MB RAM chip set? > >-Mike Nope, most amigas have only 1MB chip ram. The only amiga to ship with the 2MB chip set is the A3000(T) at the moment. A wild guess is that the other amigas soon will have the new chip set, unless they want to wait to include the new custom chips as well :-) /Jorgen -- email dvljhg@cs.umu.se | DUMII: Sentinel of the scales Everything I say is always true, just apply it to the right reality. "Credo, quia absurdum est." Credo (dei) in absurdum est?