On Fri, 13 Apr 101 g.baltissen@hccnet.nl wrote: > Hallo Bogax, > > > I've never used the thing and perhaps I misunderstand what you're > > saying, but you shouldn't need two 8237s. > > Memory to memory is done with two DMA channels, channel 0 is the > > source and channel 1 is the destination. > > Found the section so you were right, thanks! > > But now the bad news: > The the 8237 needs FOUR cycles for every single operation. A DMA of one > byte from memory to memory would cost eight cycles. OK, even when running > on 1 MHz it still is a better performance then when the CPU had to do the > job. But you can forget the real 1 MHz performance the REU can run. Until > now I haven't found an idea to speed things up except using 2 IC's. But > this only would permit 256KB/sec. Remember: the 8237 will be clocked from the ISA bus, which runs at 8mhz! ;) > > Anyone has ideas? > > Groetjes, Ruud > > http://Ruud.C64.org/ > > > > - > This message was sent through the cbm-hackers mailing list. > To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi. > - 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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