The (E)ISA bus is more-less the external memory/IO bus of the x86 processor. So accessing the card from PC program is nothing more than to perform an "in" or "out" instruction - see your x86 assembler reference. When programming in high level language, there are "wrapper" function for this (e.g. the port[] pseudo-array in Turbo Pascal, outport(b)/inport(b) functions in C). However, it is not trivial to perform "in" and "out" in WinNT+ (includes 2k and XP) environment, because of the protected mode of processor used for these OS; nevertheless there are "enabler" utilities to perform this.

From the card/HW point of view, you should latch the status of the databus when the address bus matches the card's address and /IOW is active (low); similarly when address match and /IOR is active, the card should output a value onto the data bus. Pretty similar as if you work with '51 and interface some IO as external data memory mapped; with /RD and /WR on '51 acting the same as /IOR and /IOW on (E)ISA.

I think you can find more information by googling; or start at http://www.epanorama.net/links/project_pc.html to get tons of information.

Jan Waclawek