Re: PCcard (2)

From: David M. Lloyd (
Date: 2001-04-09 16:10:58

On Mon, 9 Apr 2001 wrote:

> If you're wanting to do DMA from an ISA card, you can have the DRQ
> lines cause an interrupt on the c64, which would react by tristating
> the 6522(s) and then asserting DACK.  After this, you can use "Pseudo
> DMA", which consists of convincing the card that its on a (very slow)
> DMA channel by manually toggling the lines to clock data in.  Mind
> you, ISA's dma doesnt provide the destination address from the
> expansion card.  It's actually the DMAC's responsibility to do this,
> so we dont need to change the address lines.  We simply provide ISA
> bus signals. *wink*

Or you can do it in hardware with a 6844 or 68B44 from Motorola, you
should still be able to get them somewhere.  Then you can have _real_ DMA
at C64 bus speed.

- D


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