Re: YMF724

[Alan Cox <alan lxorguk ukuu org uk>]

> as well as an option to use the PCI interrupt line (INTA#).
> I was assuming that the chip is wired this way, and that I can
> specify a "normal" IRQ line, but I have no specs to back this up.

Hopefully. When its running in windows does it show up on an ISA IRQ as
well ?

> it looks like PC/PCI encodes the ISA dma channel number over
> a set of pins.  The DDMA support seems to have a set of registers

PC/PCI is a sideband bus for passing the ISA info down.  
> 
>   - Am I incorrect in assuming that my motherboard, and in
>     general, motherboards with YMF724's on them are wired directly
>     to the interrupt controller?

No idea

>   - If the legacy block exists so that old software can access
>     to work).  Why?  How does the chip work with legacy DOS
>     software that doesn't know about the chip?

You load a magic TSR ?

>   - How does PC/PCI DMA work?  Are there any specs (I did some
>     searching and turned up nothing yet).

Ive not found any either

>     (and knowledge of the DMA width).  With such routines, DDMA
>     would be a simple matter of initialization and proper indirection.
>     Is this true or is this statement simplistic/naive?

The existing code  is a bit naive about DMA. Having said that adding
higher "magic" DDMA channels should be possible. It will be ugly tho