> If the DMA stopped the CPU:
> 1) why 3 dma channels if you can use 1 a time?
> 2) why an interrupt to acknowledge the end of the dma?
> 3) what DMA itself would be useful for???
>
> DMA is used everywhere because you can transfer memory WITHOUT the cpu
> handling it. I've never found a consolle where the DMA halted CPU
> processing, but since I don't konw anything about AGB, it
> *might* be. In
> this case, I'd be very glad if someone could explain me why
> one should use a
> blocking DMA.

GBC halts when doing General Purpose DMA.
And HBlank DMA in h-blanks.
It's faster than creating a copy loop.
But if you have block copy instructions.. (don't know if GBA has), I see no
point in blocking DMA too.

Dark Fader

> ---
> Giovanni Bajo
> Lead Programmer
>
> Protonic Interactive
> www.protonic.net
>
> a brand of Prograph Research S.r.l.
> www.prograph.it
>
>
>
>
> -----Original Message-----
> From: Matthew Davies [mailto:MDavies@...]
> Sent: Tuesday, August 01, 2000 11:11 AM
> To: AGB list (E-mail)
> Subject: [gbadev] DMA dilemma!
>
>
> Hi,
>
> I cannot figure it out. Does DMA transfers run
> asynchronously with the CPU
> or not? I mean, when a DMA transfer is intiated does the CPU
> wait until its
> finished or does it not. The fact that there are 3 priority
> levels of DMA
> seem to suggest that a DMA can interrupt another, and you
> need a the CPU
> running to start a second DMA transfer to do the
> interrupting. Also, I have
> 4 DMA transfers on priority level 3 running back to back and
> they do not
> interfere with each other - either the CPU waits or the DMA
> transfer is
> amazingly fast. Which is it? Anyone??
>
> Cheers!
> Matt J. Davies
> Programmer
> Acclaim Studios Ltd.
>
>
>
>
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>
>
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