Path: utzoo!mnetor!uunet!steinmetz!ge-dab!codas!killer!elg
From: elg@killer.UUCP (Eric Green)
Newsgroups: comp.sys.cbm
Subject: Re: Cartridge Port
Message-ID: <3162@killer.UUCP>
Date: 31 Jan 88 07:19:17 GMT
References: <3231@cbmvax.UUCP>
Organization: Bayou Telecommunications
Lines: 28

in article <3231@cbmvax.UUCP>, fred@cbmvax.UUCP (Fred Bowen) says:
> In article <3021@killer.UUCP>, elg@killer.UUCP (Eric Green) writes:
>> Ultimax mode... only 4K of RAM is accessible. Period. You can't read any other
>> RAM, and, what's even more mystifying, you can't WRITE any other RAM. Boggles
>> one's mind... "WHAT the HECK is THAT in there for?!".
> The Ultimax (aka Max Machine) was intended to be the cheapest CBM system,
> below or possibly replacing the VIC-20.  It was primarily a game machine
> using the VIC-II chip, just like his brother the C64.  He did not even have
> BASIC in ROM, although a BASIC cartridge was to be available.  Well, in the
> US at least, Max died in infancy but not before leaving his mark on the C64,
> which was (ta-da) two machines in one, a Max and a C64.

Another mind-boggling thing: The VIC-][ chip in the C64 can't see the regular
character-set ROM if the Ultimax mode is enabled. I guess the character set
had to be on the plug-in cartridges? Beats me... all I know was that I wrote a
short program at $900 that banked Ultimax in (via a jumper to a CIA), paused
for a few secs (with irq's off, of course), then banked Ultimax out -- and the
character set evaporated during that pause. Which means that anybody who wants
to take advantage of Ultimax had better make sure that it only takes over
while BA and S02 are both high (i.e., when the VIC-][ chip isn't active). As
for why one would want Ultimax, figure out for yourself how you could get your
own custom Kernal into the machine without a ROM swap....

--
Eric Lee Green  elg@usl.CSNET     Asimov Cocktail,n., A verbal bomb
{cbosgd,ihnp4}!killer!elg              detonated by the mention of any
Snail Mail P.O. Box 92191              subject, resulting in an explosion
Lafayette, LA 70509                    of at least 5,000 words.