Trackstar - How did it work?

[jeffh@oakhill-csic.sps.mot.com (Jeff Hunsinger)]

I recently saw the Trackstar board at a garage sale. I didn't pick it up because the
guy wanted more for the board than I can pick up a IIe for. For those that aren't
familiar with it, it places a II in a PC. It allows the II to access the PC's drives
as its own. It also receives keyboard input from the normal PC keyboard. It may
allow use of the PC's serial and parallel ports, but I don't know. What I was
wondering is how does this beast work? Does the PC just sit waiting for memory
accesses to key locations? Is there an intercept somewhere? Were the Apple ROMs
patched?

Any details greatly appreciated...

Jeff