Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!psuvax1!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.hardware Subject: Re: The A1000 Memory Hack Summary Message-ID: <12656@cbmvax.commodore.com> Date: 13 Jun 90 19:49:00 GMT References: Reply-To: daveh@cbmvax (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 51 In article peck@ral.rpi.edu (Joseph Peck) writes: >If you can't, Dave Haynie has written an article on adding some additional >hardware that causes the memory to autoconfigure. It doesn't seem very >complicated, and allows you to run those strangely copyprotected programs >with the increased memory. Just a little clarification here. That hack I did way back gives you what's essentially the same memory decoding as on an A500 or A2000. What it does is modify the memory mapping logic on the A1000's daughterboard. The circuit detects an access to the 512K region starting at $00C00000, and fools the A1000's decoding PAL into thinking that's really $00000000, so that it'll generate DRAM selects instead of custom chip selects. The 1.2 OS on up have special code to add memory in this region. That's really not Autoconfig, but a special case. To the user, it ends up being pretty much the same thing anyway. >One more final problem. Some expansion boards already use Dave's technique >for simple autoconfigure, and only ONE device at a time may do so. Check >your memory expansions documentation. Real Autoconfiguring boards would never conflict with this memory. However, most if not all of the "hacked inside your A1000" type boards, like the Spirit Inboard, aren't true Autoconfig. These instead use the motherboard space at $00C00000, just like my mods to the Chris Erving hack do. So you most likely can't use the two hacks together, though a plain Chris Erving modification and an Inboard-type gizmo might peacefully coexist (no reason, other than power and noise problems, that they shouldn't). >To that end I would like to say that I personally would add only the 512k >hack to the motherboard, and add Dave's autoconfigure circuitry. That's what's in my A1000. I put that modification into it in early '86 or so, and it still works great. But, like any hack, the quality of the work may have a great deal to do with how well the thing works. And there are no guarantees; it's reasonably easy to damage your machine if you're not experienced with this kind of thing, and there's no guarantee that such a hack won't cause problems with other add-on hardware. My best advice is know what you're doing before you get into any of this. By the way, just in case anyone's planning to ask, I don't presently have a copy of the hack I wrote up, or the accompanying IFF schematic. I was running from floppies back then, and somehow that one got misplaced or trashed or some-such. The article is still apparently around on BBSs and similar places, but I won't be able to supply it, so don't bother asking. -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "I have been given the freedom to do as I see fit" -REM