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From: knudsen@ihwpt.UUCP (mike knudsen)
Newsgroups: comp.sys.m6809
Subject: More on MultiPak Upgrades (CocoIII)
Message-ID: <1302@ihwpt.UUCP>
Date: Mon, 15-Dec-86 13:43:12 EST
Article-I.D.: ihwpt.1302
Posted: Mon Dec 15 13:43:12 1986
Date-Received: Tue, 16-Dec-86 22:46:58 EST
Distribution: net
Organization: AT&T Bell Labs, Naperville, IL
Lines: 38

(coco3 bugs for the line eater)
The latest (Jan 87) RAINBOW has quite a good article
on upgrading MultiPak Interfaces (MPIs, toasters) for
the Coco III.  It shoots down some notions that some of
us have had.  Points made are:

(1) The old gray MPIs, plus some rugged white ones with
the same guts, need only a PAL replacement.
The later white ones were a cost-reduced design that needs
a satellite board to fix.  Yes, Jim O., the old ones ARE better!
Detailed instructions are given to install the satellite board
yourself (it ain't trivial!).

(2a) No matter how well your MPI seems to work with CocoIII,
you had better get it upgraded to avoid subtle (?) future
problems.  Thus saith the gods at Fort Worth.

(2b) You need the upgrade even tho you don't install 512K RAM.
Rumor had it that 128K operation was OK w/out upgrading the MPI.

(3) The upgrade not only busts the ghost at FF9F (of the MPI
control reg at FF7F) but also "locks out" addresses FF80 and up
(I guess by witholding the E and Q clocks).
This is to avoid bus conflicts with the GIME's regs.
(WHY lock out FF80~8F?  Not used by GIME.  Yet.)

(4) Due to (3), your upgraded MPI will no longer work with
CocoMax, WordPak, etc etc EVEN ON A COCO I or II.
So the article tells how to hack a switch into your toaster
to disable the upgrade (degrade?  retrograde?).

What I'd like is to always keep the ghost disabled but select
the FF80 mode.  Probably not possible with the PAL upgrade.

(5) Article gives part numbers for ordering the PAL or satellite
board from RS National Parts.

	Happy hacking, mike k