Re: PC-card (4)

jbevren_at_starbase.globalpc.net
Date: 2001-04-13 15:55:58

On Thu, 12 Apr 2001, john/lori wrote:

> > 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.

I _completely_ forgot about the ram-to-ram block copy feature. ;)

> 
> 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.
> 
>  bogax
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