On Sun, 25 Feb 101 g.baltissen@hccnet.nl wrote: > Hallo allemaal, > > I have two question that possibly fits in this discussion: > The SCPU uses its own memory to maintain maximum speed. But the the content > has to be copied in some or another way to the original memory > - how is this done? Probably DMA? DMA > - what range is copied and how does the mechanism know? All 64k. I'm not aware of how often. :) The V2 spcu's can 'optimise' and only copy certain regions to the c64. > We already discussed replacing a non 6502 CPU by 6502 + Hardware. I prooved > it can be done. Now to find a way to be able to use fast memory. > > This triggered another question: the 65816 can run on 20 MHz. The SIMMs > SCPU uses ar mostly of the 70 ns type. 20 Mhz means 25 ns cycles. How does > that fit? Either someone is cheating or I missed something. I hope the last > and that someone can tell the trick. the rams used in the scpu are 32 bits wide. You can access 8 bits in a 4bank interleave. :) That gives us the ability to access 70ns/4 ;) It's quite possible to access a byte every cycle, minus the time needed to set new dram rows up. > > Groetjes, Ruud Greetings, David - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.
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