Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!mordor!sri-spam!rutgers!cbmvax!fred
From: fred@cbmvax.UUCP (Fred Bowen)
Newsgroups: comp.sys.cbm
Subject: Re: Cartridge Port
Message-ID: <3255@cbmvax.UUCP>
Date: 2 Feb 88 15:21:22 GMT
References: <3231@cbmvax.UUCP> <3162@killer.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 38

In article <3162@killer.UUCP>, elg@killer.UUCP (Eric Green) writes:
> 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?

	Yep.  Most games were bit mapped or used their own characters anyhow.
	Also remember the VIC sees the character ROM not at $D000 like the
	processor but in bank 0 or 2 only, at $2000 and $9000, thru the same
	magical PLA that dreams up Max mode when the /game goes down.

> ... 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).

	Ultimax mode is (was?) intended for game cartridges which are
	installed at power up, so this is no problem.

> ...why one would want Ultimax, figure out for yourself how you could get your
> own custom Kernal into the machine without a ROM swap....

	Not using Max mode unless you are playing truly bizarre "hardware"
	games with /game.  Even so, in Max mode the image of the "kernel"
	ROM also appears at $3000, and all but 2-4K of RAM evaporate. Add
	to this the VIC-ercises you mentioned above, and you get some idea
	why it's so hard to maintain compatiblity in newer computers with
	fellas like yourself running around :-)  But I guess that's why the
	64 type computer still lives, eh?

> 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.
--
-- 
Fred Bowen			uucp:	{ihnp4|rutgers|caip}!cbmvax!fred
				arpa:	cbmvax!fred@RUTGERS.EDU
				tele:	215 431-9100

Commodore Electronics, Ltd.,  1200 Wilson Drive,  West Chester,  PA,  19380