Test plug configuration?

[Jeffrey L Bromberger]

After booting the diagnostic disk for my UNIX-PC, when I wanted to test 
the serial port (/dev/tty000), it said I needed a special plug.  How 
should one wire this? Is there a source for getting one ready-made?
The reason I ask is that I believe that my serial port is dead.  Any
help would be greatly appreciated.  Thanks.
-- 
Jeffrey L. Bromberger
System Operator---City College of New York---Science Computing Facility
Anywhere!{cmcl2,philabs,phri}!ccnysci!jeffrey	jeffrey at ccnysci.BITNET