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From: milliga@cat4.cs.wisc.edu (Michael Milligan)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Fabricating an expansion board for A500
Message-ID: <1991Mar6.222406.11851@daffy.cs.wisc.edu>
Date: 6 Mar 91 22:24:06 GMT
References: <1991Mar1.210755.16835@daffy.cs.wisc.edu> <1991Mar6.104401.18859@agate.berkeley.edu>
Sender: news@daffy.cs.wisc.edu (The News)
Organization: University of Wisconsin CS Dept
Lines: 27

In article <1991Mar6.104401.18859@agate.berkeley.edu> vincelee@tornado.Berkeley.EDU (Vincent H. Lee) writes:
>
> This is actually very easy.  I have one such circuit in my 500.
> 
> Simply connect the 86 pins to the first 86 pins of the ZorroII Slot... Really.
> Then, connect RES (86) to RESB (94).  If your device needs a 7Mhz clock,
> input C3(14) and C5 (16) to an Xor gate.  Invert the output, and connect to 
> 7ME (92).  That's it!
> 
> -Vince
> .

This isn't quite what I had in mind.  I'd like to put together a board that
has at least 2 Zorro II slots, so I'm still in need of information on handling
bus mastering, buffering, etc. . .

I basically need information on how the Buster chip in the A2000 (I think that's
the chip) and/or the PAL's work to handle multiple expansion cards.  I don't
have access to A2000 schematics, which is why I need this info.
 
I had planned to pull the 7M signal right off the motherboard since Agnus spits
it out. . . No sense in having a circuit to do something redundant.

-- 
"I'm wasted, and I can't shutup!"     |  Michael Milligan, Professional Student
 -- saying on a chars T-shirt from    |   "Nothing I say can or will be used
    cartoon Badgers & Other Animals   |    against me in a court of law."