> > On Fri, 10 Feb 1995 11:25:42 +0000 (GMT), Nigel J Kettlewell said: > > OK, so how about putting in your own RAM as well as a new CPU? Memory's > > cheap, despite what SAMCo et al used to charge for it. That way, surely you > > could stop the CPU caring what the ASIC says about RAM? > > This is what Simon proposed some time ago (that is, adding a souped up CPU > and a chunk of memory, neither of which the ASIC knows anything about, and > some kind of linkage which allows the new CPU to write to the Sam's memory > if it wants (which it has to do in order to display a picture)). >
You could be really cock-eyed and have split the memory banks - let the ASIC deal with the lower 256K and the new processor deal with the top 256K as fast as it likes. Ok, this means that any video data will have to be in the lower 256K. Just think of all that refresh-logic, bank switching circuitry that you'd have to design..... -AG
