Fast DIO help

[texon]

I'm starting on a project with a simple spec, but I'm stumped
on the hardware issues: I have a small analog-to-digital board
with 8 parallel output bits, plus some clock lines, running at
10Mhz. I need to get these bytes into my gentoo box.

USB and Firewire are out because they add too much hardware
design overhead to the small ADC board. Parallel port is too
slow. One possible solution is to buy a fast Digital-IO board
from someone like National Instruments, and just read the
8bits and clock directly via an appropriate off-the-shelf Comedi driver.
However, this solution is too expensive: a single DIO card costs
more than the gentoo box and ADC board combined.

I just finished building a gentoo compact flash PC104 board
computer and I'm not averse to using a small (gumstick, even)
linux board to hook up to the ADC, but I don't know anything
about how to read fast digital lines directly into linux memory.
On a PIC microprocessor, sure I could, but I need help here figuring
out how to get this data into main memory.

Would appreciate any pointers to documentation (PCI bus docs maybe?)
on how I might force these bytes from the ADC into my computer.

Naturally, thanks in advance.

texon

(And gentoo makes a totally cool compact-flash embedded linux!)