Path: utzoo!attcan!uunet!cs.utexas.edu!usc!apple!oliveb!amiga!cbmvax!daveh From: daveh@cbmvax.UUCP (Dave Haynie) Newsgroups: comp.sys.amiga.tech Subject: Re: DTACK* or not to DTACK*, that is my question... Message-ID: <7617@cbmvax.UUCP> Date: 10 Aug 89 18:22:44 GMT References: <120525@sun.Eng.Sun.COM> Organization: Commodore Technology, West Chester, PA Lines: 32 in article <120525@sun.Eng.Sun.COM>, raz%kilowatt@Sun.COM (Steve -Raz- Berry) says: > Right now I have a way of disabling the 68K on the 2000's motherboard, > but I would be very interested in hearing a brief description from > you on the particular timing involved. The way I am approaching it now > is to wait for the Ami to come out of reset before I issue CBR*. That's pretty much what the A2620/30 do. They sit and wait for reset to end, and actually for the first cycle to start, then kick in the CBR* -> CBG* -> BOSS* sequence. The main reason for that is that we weren't sure just when the 68000's arbiter woke up when we did the A2620, and I didn't have any reason to change it for the A2630, though I'm certain there's no reason to wait for the first cycle to start. > Also if you have any thoughts that you would care to share on any > particular signals to watch out for, I'd be mighty interested. As > George said, I keep getting knocked back to square one, (lately on the > clk high to FC valid timing - why oh why is it different than address > valid to AS* asserted???) and I'd like to eliminate as much of that as > possible. Clock high to FC/Address is just a different spec than FC/Address to AS*. OK, it's been awhile since I looked at the 68000 spec, but certainly on 68030s, FC and Address are the same thing, timing wise. Since function codes are really an extension of the Address, you wouldn't expect them to act any differently than the Addresses do, eh? > Steve -Raz- Berry Disclaimer: It wasn't me! I was volatilizing my esters. -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy Be careful what you wish for -- you just might get it