Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!uunet!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: HARDWARE HACK: 2630 accellerator card in a Zorro II slot
Message-ID: <21643@cbmvax.commodore.com>
Date: 16 May 91 14:45:03 GMT
References: <72302@microsoft.UUCP> <21607@cbmvax.commodore.com> <1991May16.063945.7032@Informatik.TU-Muenchen.DE>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 38

In article <1991May16.063945.7032@Informatik.TU-Muenchen.DE> vollath@Informatik.TU-Muenchen.DE (Ulrich Vollath) writes:

>In article <21607@cbmvax.commodore.com>, daveh@cbmvax.commodore.com (Dave Haynie) writes:
>|> Ok, here's the deal.  The 86 pin edge on the A500 or A2000 is actually more

>You probably mean A1000? So there is a way to stuff these neat Processor
>cards in my good old A1000? :-)

Yeah, that's the one.  If you don't have any real DMA devices hooked up, you 
can at least in theory hook an A26x0 or probably other accelerator card to an
A1000 or A500.  While these machines don't have the coprocessor interface, that
isn't an issue unless there's other DMA around.  So the CBR/CBG lines can go
directly to the BR/BG lines of the 86 pin edge (they naturally correspond,
anyway).  There is no /BOSS line on the 86 pin edge, but there is /BGACK, which
again, in the absense of any other 68000 style DMA, can be used.  This requires
that pin 62 of the 86 pin edge be run to pin 20 of the accelerator board.  And
it's a good idea to connect pin 62 of the accelerator board to +5V, now that I
think of it.  The one final missing signal is the 7MHz clock.  This could be
tapped off the internal 68000, or created from the CDAC clock.  CDAC is a 7MHz
clock that trails the 7M clock by 90 degrees, or 35ns.  If you can delay it by
another 270 degrees, or 105ns, you get 7M back.  The best way to achieve this
is by running CDAC though a fast inverter, like a 74F04, and then a 30ns delay
line.  You might be able to get by with a 100ns delay line, instead, though I 
don't know for sure (that's right on the edge of CDAC to 7M tolerance that
the A26x0 requires).

As for how to put this all together mechanically so it works good, I really
don't know, that's something you'll have to work out on your own.  The key idea
from the electronic point of view is to keep wires as short as possible.

>Ulrich Vollath                 email: vollath@lan.informatik.tu-muenchen.de
>Munich Institute of Technology voice: 004989/2105-8102 (result: -8099.62992874)


-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
      "That's me in the corner, that's me in the spotlight" -R.E.M.