So, you remove everything from your S100 system but the CPU. You add a single
board with a 64K SRAM chip, a CF card (and IDE) to emulate all drives, RS232,
and USB and Ethernet (likely buffered by a PIC that does the heavy lifting so
that they look like simple serial I/O). Leave your drives in place so it
looks right but save wear and tear on drives and old hardware. The board is
probably under $150.

Do you want:

a) A fixed simple memory map so the same configuration works for everyone
(and what would that map look like?).

b) A small FPGA managed by the USB and a PIC that can configure the memory
map so you can keep a favorite video board or experiment or whatever? For
example I have a board with three 12 bit D/A that drives an old Tektronix
storage scope for high res plots.

c) a or b with a video generator on the new card?

-- Charlie Springer