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Path: utzoo!watmath!clyde!bonnie!akgua!sdcsvax!sdcrdcf!hplabs!bragvax!david
From: david@bragvax.UUCP (David DiGiacomo)
Newsgroups: net.micro.6809
Subject: Re: M6829 Memory Management Chip
Message-ID: <278@bragvax.UUCP>
Date: Mon, 17-Dec-84 20:13:02 EST
Article-I.D.: bragvax.278
Posted: Mon Dec 17 20:13:02 1984
Date-Received: Fri, 21-Dec-84 02:18:32 EST
References: <437@mako.UUCP> <302@aesat.UUCP>
Organization: Brag Systems Inc., San Mateo, CA
Lines: 15

I think the 6829's unpopularity is well justified; by today's standards
it is a very small, very slow, very expensive RAM.  Motorola would have
been better off building a tiny chip with just the "fuse" logic (and
maybe a single step NMI generator).  Of course, they could have just put
another stack pointer in the 6809.

Anyway, any hobbyist who is tempted to use the 6829 is probably better
off duplicating the "fuse" logic (maybe in a PAL) and using modern fast
static RAMs for the MMU (maybe 2148s-- not really modern).  It might be
better to build an adder type MMU a la PDP-11 if the additional delay is
tolerable, unless there's someone crazy enough to do paging on a 6809.

-- 
David DiGiacomo, BRAG Systems Inc., San Mateo CA  (415) 342-3963
(...decvax!ucbvax!hplabs!bragvax!david)