Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!seas.gwu.edu!kilian From: kilian@seas.gwu.edu (Jens Kilian) Newsgroups: comp.sys.atari.st.tech Subject: Re: Possible 68020 problem Keywords: 68020, 68030, 68040 Message-ID: <2585@sparko.gwu.edu> Date: 22 Jan 91 20:03:56 GMT References: <9101151859.AA11212@sun.soe.clarkson.edu> <1991Jan21.115306.17458@ifi.uio.no> Sender: news@seas.gwu.edu Reply-To: kilian@seas.gwu.edu (Jens Kilian) Organization: The George Washington University, Washington, D.C. Lines: 22 In article <1991Jan21.115306.17458@ifi.uio.no> jkr@ifi.uio.no (Johan Kristian Rosenvold) writes: > >My revision of the developer system doesn't say anything about this. Are the >chip register adresses defined as a negative offset from the top of the addressable >range or as the absolute address 00 FF FA 01 ? > A pity that Atari didn't document this. This is exactly the same kind of brain-damage that causes the 640 K memory limit on you-know-who PCs. The whole confusion probably stems from Atari's use of 24-bit addresses in their meager documentation. Did they never expect to use a 68020 in future models ? My advice is to use 16-bit addresses for hardware registers (if you REALLY must use the registers, that is ...), and cursed be those who don't ! Jens Kilian -- \/// Internet: kilian@seas.gwu.edu |Snail: 4715 MacArthur Blvd. \\\/ /// UUCP: ...uunet!seas.gwu.edu!kilian| Washington, DC 20007 \\\ \\\ [These addresses will change (to kilian@cc.gatech.edu) soon] /// /\\\ "Wos deht ich-en so gern haage, awwer er spihrt doch nix ..." ///\