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From: pegram@kira.UUCP (Robert B. Pegram)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: TT VME Bus, and extending it
Message-ID: <1991May22.180217.27664@uvm.edu>
Date: 22 May 91 18:02:17 GMT
References: <17302@chaph.usc.edu>
Sender: news@uvm.edu
Organization: Univ. of Vermont, Eng., Math., and Bus. Admin. (EMBA) Computer Facility
Lines: 42

From article <17302@chaph.usc.edu>, by baffoni@aludra.usc.edu (Juxtaposer):
> In article <1991May16.163752.24994@daffy.cs.wisc.edu> carter@cat23.cs.wisc.edu (Gregory Carter) writes:
> <stuff deleted>
>>
>>However, a german company makes an extended card cage for the TT/MEGA STE
>>and VME cards for graphics and cpu accelerators.  It was shown at the last
>>CeBit show, I think.
> 
> 	Is it possible/have they already made  an accelerator card that  uses
> the buslines available on the VME/Atari (TT/mega)bus slots?  Like for instance 
> a 68040 board that takes over the machine (I've seen stuff like that for the 
> Mac and thought you might be able to do the same thing) and delegates the on
> board cpu as an I/O handler (and other CPU wasting projects).  However, I could
> be mistaken (_I_ don't use 'em, let alone build 'em), but would something like
> that be possible for the TT?  Dave Small has already shown that it's possible
> for the ST...:)

Nope, it isn't possible, at least at the moment.  The main reason is
that the TT's VME bus is only D(ata)16(bits), A(ddress)24 (one vme
connector), which is fine for a Mega STE, but you need D32, A32 to
really handle an 030.  I'm also not completely clear whether VME
supports Bus mastering properly, we have the spec here, but I was only
interested in the electrical characteristics when we were putting our
DSPs on the VME backplane.

This does bring up a pet idea of mine however.  I wonder if it would
be difficult to implement the electrical part (buffering etc.) of the
missing VME connector.  So that one could connect a TT to an external
VME Backplane in some nonstandard way and have a true D32, A32 VME
card cage for it.  Comments anyone?

Downers deleted 8-)
>>
>>--Gregory
> 
> -Mike

Bob Pegram

pegram@griffin.uvm.edu
	or
...!uvm-gen!pegram