Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!amiga!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.amiga.tech
Subject: Re: New 6.0 2500 Hates 68000 Mode!
Message-ID: <6782@cbmvax.UUCP>
Date: 5 May 89 20:57:08 GMT
References: <576@dialog.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 44

in article <576@dialog.UUCP>, root@dialog.UUCP (Christian Motz) says:

> In article <780@manta.NOSC.MIL> dwi@manta.NOSC.MIL (Steve Stamper) writes:
> I just got my new Rev. 6 A2000 myself, and while I *LOVE* the 1 MB
> Chip RAM, it seems as if the machine is not as stable as my old
> Rev. 4.4. 

There's no obvious reason for this.  I wasn't the only one working on the
Rev 6 board, but the only thing I did to it was change the motherboard
memory system.  If anything, I'd expect it to be a little more forgiving
that the older systems -- you can't really get 150ns DRAMs in the 1 meg
package, so we use 120s, which would increase the chip bus timing margins
considerably.  As far as I know, nothing was changed that should have any
effect on the expansion bus.

> unstable and crashes frequently, i.e. when Zoo is started), while
> it works perfectly with a Rev. 4.4 board.

> Could anyone from C=A clarify what has been changed on the new
> mainboard? What for example is the upside down piggyback PCB near
> Agnus for? 

That's a tower to allow the system to use static column memories
instead of the normal memory.  Should not change anything.

> Has the bus timing changed and is it possible that older expansion boards 
> don't work? I (and I am sure quite a few people) would appreciate any 
> comment. Dave, are you listening?

The only thing that's likely to change bus timing in the new system is
the 1 meg Agnus, but it actually changes timing for the better.  Agnus
creates the system clocks: C1, C3, CDAC*, and 7MHz.  Old Agnus was a
tad sloppy, in that the C1/C3 to CDAC*/7MHz skew jittered more that we'd
have liked.  The new Agnus makes the clocks differently, and as a result
they're much more stable.  Though I'm open to any specific examples of
trouble -- we can certainly look for any problems on this end if we have
an idea of what to look for.

> Christian Motz       uucp: ...!uunet!mcvax!unido!pfm!nadia!dialog!root
> "Trust me, I know what I'm doing!" -- Sledge Hammer         Bix: cmotz
-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
              Amiga -- It's not just a job, it's an obsession