Re: Hands on PCI interface ...

From: Jonathan Kirwan (jkirwan_at_easystreet.com)
Date: 02/04/05 

Date: Fri, 04 Feb 2005 19:58:46 GMT

On Fri, 04 Feb 2005 16:25:30 GMT, nico@puntnl.niks (Nico Coesel) wrote:

>I think it is possible if the ISA card can use 1 interrupt or share
>interrupts. You'll need some intelligence to convert ISA DMA to PCI
>bus mastering (which is more or less the same, only the addresses are
>generated at a different spot).

The problem isn't that, it's the timing requirements of ISA DMA. They simply
cannot be met by the PCI bus using normal PCI transactions. This is part of why
the sideband signals are required to the main chipset, so that the chipset can
be informed about the non-standard nature of certain transactions. Without
them, the DMA timing itself cannot be supported on the PCI.

>The amount of I/O and memory addresses
>can be preset on the PCI card so substractive addressing isn't needed.

I suppose that's possible, of course. Usually, ISA bus transactions are handled
as subtractive decoding, though.

Jon

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