Re: PC-card (4)

From: john/lori (
Date: 2001-04-13 01:07:10

> Now I have the idea that what you mean with DMA is what the REU does: it 
> copies/swappes an amount of memory situated outside the C64 from/to/with an 
> amount of memory inside the C64. I haven't thought about this idea. But you 
> need two 8237's to perform this trick. And then you need 32 bytes for the 
> DMA alone. 

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.

and (iirc) the chip is accessed through 16 locations, 4 address
lines, and each access toggles a fifth internal address bit and
there's a command to reset that bit to a known state.

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