I have what looks like a Zenith 4-port serial I/O S100 board:
http://q7.neurotica.com/Zenith_front.jpg
The Z100 Technical Manual mentions a Z-204 Multiport Input/Output board:
could this be the one? Does anyone have a manual?
Mike Loewen mloewen at cpumagic.scol.pa.us
Old Technology http://q7.neurotica.com/Oldtech/