dean.gaudet@canremote.uucp (DEAN GAUDET) (09/11/89)
Disclaimer: This is just idle thought. I do not have an A2620 and do not claim to have knowledge of its workings. No flames please! Since the A2620 allows you to use the 68000 through a startup selection, wouldn't it be possible to use BOTH processors? ie: Use the 68020 as an amiga 2500, and make the 68000 think it's just a plain 2000. I realize that problems exist with video and audio handling. I would think that handling of resources could be done quite easily (ie: it would require some reworking of code to check if the other processor had allocated a resource already). RAM is another problem - but if you are running the 68020 off 32-bit ram, the 68000 would be home free in 16-bit ram. You could use the 68885 (MMU) to remap AbsExecBase for the 68020. Comments? I'm not about to try it myself (see above disclaimer). I think the least that could be achieved is to use the 68000 as a slave for background processing... Dean Gaudet DGaudet@UNCAMULT.BITNET - or - Dean.Gaudet@CANREMOTE.UUCP --- * Via ProDoor 3.01R
daveh@cbmvax.UUCP (Dave Haynie) (09/15/89)
in article <89091323592891@masnet.uucp>, dean.gaudet@canremote.uucp (DEAN GAUDET) says: > Since the A2620 allows you to use the 68000 through a startup selection, > wouldn't it be possible to use BOTH processors? While the A2000 design would permit the use of both CPUs simultaneously, the A2620 itself doesn't. The 68020 is held in reset until the A2620 logic takes the bus from the 68000. And to get the 68000 back, the 68020 is forced back into reset. Why? It made the design _so_ much easier, especially considering that the original A2620 design wasn't intending to let the 68000 back on at all. Why? I dunno, I didn't get on the A2620 until after that decision had been made, and I thought, "hey, that's stupid, we should be able to kick the 68000 back in if necessary", and found the simplest way to do that, given the existing A2620 design. > ie: Use the 68020 as an amiga 2500, and make the 68000 think it's just a > plain 2000. That would be a major software undertaking. If it would work at all. More likely, you'd use the 68000 as a device under the 68020's control; maybe have the 68000 run a custom filesystem and other I/O, or similar. It would still take lots of new software, but at that level could at least break the question of "what does the 68000 do" into bite-sized pieces. > You could use the 68885 (MMU) to remap AbsExecBase for the 68020. that's 68851 And yup, it could remap AbsExecBase. > Dean Gaudet -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough