Re: PC-card (4)
Date: 2001-04-13 10:43:18

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.

Anyone has ideas?

Groetjes, Ruud

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