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Re: AmigaONE && Debian (unstable?)


Gabriel Paubert wrote:

Hmm, the DMA controller is called the 8237. The 8259 is the PIC, aka
Painful Interrupt Controller.

Sorry! You are right, I always get those to numbers confused ;).

Once upon a while, Intel introduced a couple of PCI/ISA bridge with
enhanced DMA capabilities: - the 82378ZB with scatter/gather DMA with 32 bit addressing
- the 82379AB with an I/O APIC (meaning Awfully Painful...) and
another kind of enhanced DMA without scatter/gather but with guess what ... 27 bit (yes!) addressing capability.

If you want it, I still have the pdf from March 1996 on my disk.
Note that 27 bit was not bad since very few machines at the time could even have such a tremendous (128MB) amount of RAM.

The Articia data sheet specifies only an "i8237", and the registers it lists are what the original i8237 had, but I'd be interested in the pdf file, to see where abouts the extra registers are placed (maybe it will help me make sense of the brief mention of the "32bit DMA" registers).

The PreP specification said that the ISA bridge should
be the Intel 82378ZB, so Intel stopped producing it and
no other Intel bridges since then have to my knowledge
implemented the same ISA DMA engine. Only Winbond (again to
my knowledge) copied it in the 83C553 and 83C554 bridges.

Our board isn't a PReP. I think it's supposed to be a POP.

I have Winbond 83C553 or 83C554 on my boards, but I have no devices that use ISA DMA (well I could connect a floppy
but what for?).

A floppy is still a good fall back for certain situations..



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