Path: utzoo!attcan!uunet!nih-csl!lhc!adm!cmcl2!uupsi!sunic!news.funet.fi!tut!mt87692 From: mt87692@tut.fi (Mikko Tsokkinen) Newsgroups: comp.sys.amiga.tech Subject: Re: Accessing the Chips directly Message-ID: Date: 8 Nov 90 01:55:56 GMT References: <1220@iceman.jcu.oz> <15683@cbmvax.commodore.com> Sender: news@funet.fi (#News ) Organization: Tampere University of Technology Lines: 38 In-Reply-To: daveh@cbmvax.commodore.com's message of 7 Nov 90 19:54:08 GMT [System call stuff deleted] > >ie. would my program break on an Amiga 4000 if I wrote to the > >chips for speed. > The underlying chip registers don't change unless there's a good reason for > them to change. But if there's a good reason, then they change. The most > recent such change was rather trivial -- the A3000 got a different realtime > clock, so that we could have a small amount of battery backed RAM for the > software folks to play with. But it's certainly possible for other things > to change. One other example is the color table. If you wanted a particular > color setup on a custom screen, you might try to poke color values into color > registers. Now, the OS will reset this, but ignore that for a minute. We > recently introduced the ECS chipset in the A3000. If you set up a 35ns > pixel display with that 3000, the color mapping physically changes. As long > as you used the system call for setting colors, though, everything works > properly. I must say my .02fmk worth. If commodore really moves registers in hardware area like BLTSIZ or COL00 that means NO programs without OS interface will work (as well as old OS revisions). This means they actually can call the new machine for example NEXT because amiga programs will not run on it. > So my advice is, use the OS for absolutely everything, and at as high a level > as you can. Leave the hardware alone, and you can expect to run on the > Amiga 10,000 or whatever. Bang on the hardware, and you may even break on > the A3000. If you have any detailed questions on a particular point, ask > away -- the software folks probably have a better idea about what they > expect to support in future system, and what's properly isolated from the > hardware. > >Colin Adams > Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" MIT -- Lets buy a dog!