>Theres DMA, Mapped Memory, and Programmed IO
>
>The dma calls are in isa/dma.c, does netbsd support mapped memory
>from devices?  

Yup, although with the complications of the VM system and the i386 architecture
I'm not sure how easy this is - look at something like the if_ed.c driver
to see an example.  It's also worth noting that the routines in isa/dma.c only
apply to devices that are non-busmastering.

>Programmed IO is simply read/writing a byte at a time, correct?

A byte or a word on the I/O bus ... you access this with the outb()/outw()/
inb()/inw() functions.

--Ken