Article View: comp.sys.atari.st
Article #28597Re: ST hard
From: Dave Clemans
Date: Wed, 07 Oct 1987 16:02
Date: Wed, 07 Oct 1987 16:02
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As I understand it the reason for it being difficult to impossible to add a
full MMU to the current ST's relates to the video screen refresh. Specifically,
memory accesses made to refresh the screen happen over the SAME bus as memory
This is normally invisible to you, as on the ST the cpu only needs 50% of the
available memory bandwidth, and the video system also only needs 50%. But
nothing is left over for extra or longer "cpu" type accesses.
The best way to add an mmu would probably be to speed up the memory system
bandwidth by some fraction, and probably also speed up the cpu clock.
dgc
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!mit-eddie!uw-beaver!tektronix!sequent!mntgfx!dclemans From: dclemans@mntgfx.MENTOR.COM (Dave Clemans) Newsgroups: comp.sys.atari.st Subject: Re: ST hard Message-ID: <954@dclemans.mntgfx.MENTOR.COM> Date: Wed, 7-Oct-87 12:02:58 EDT Article-I.D.: dclemans.954 Posted: Wed Oct 7 12:02:58 1987 Date-Received: Sat, 10-Oct-87 17:47:56 EDT References: <8710011017.AA11188@ucbvax.Berkeley.EDU> <858@atari.UUCP> <2269@mandrill.CWRU.Edu> Organization: Mentor Graphics, Beaverton OR Lines: 13 Summary: ST memory system