pegram@kira.UUCP (Robert B. Pegram) (05/23/91)
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
apratt@atari.UUCP (Allan Pratt) (05/29/91)
pegram@kira.UUCP (Robert B. Pegram) writes: >[T]he 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 ... The VME in a TT and a Mega STe is indeed A24/D16. In addition, it is slave-only: the VME board can't be a bus master. It is not unreasonable to suppose that a future machine from Atari might have full-sized VME with A32/D32 and full bus mastership. I have seen at least one product where you put the TT in a card-cage and get larger-sized VME connections (6U; the TT only has 3U) but the bus is still the same. The only difference is the physical size and shape of the VME cards you can plug in. There is lots available in A24/D16, especially if you aren't limited to 3U (as the TT and Mega STe are), but as I said, the VME card(s) can't be bus master(s) in the current machines. ============================================ Opinions expressed above do not necessarily -- Allan Pratt, Atari Corp. reflect those of Atari Corp. or anyone else. ...ames!atari!apratt