Erik E. Fair writes: [...]
 > My trouble is that I don't know how the Sun 3/60 has the Zilog 8530 SCC's
 > wired: how many pins are real, and how should one deal with hardware flow
 > control. My predicament is not helped by the modem docs - I miss the
 > Telebit modems of old: they had bazillions of S registers, but you could
 > always get them to do exactly what you wanted if configured carefully.
 > 
 > So, since my hunting with Alta Vista has not helped, can anyone here tell
 > me which leads are real, and whether this can be used for unidirectional or
 > bi-directional flow control?

Sun3 serial ports have these pins fully functional:
 2 TD
 3 RD
 4 RTS
 5 CTS
 7 Sig. Gnd.
 8 CD
20 DTR

Double check your cable to make sure 4/5 and 8/20
go through rather than just loop back.