RS232 & Cable Diagrams info (how it works and spec. & pin outs)
X.21  info (how it works and spec. & pin outs)
RS422 info (how it works and spec. & pin outs)
RS423 info (spec. & pin outs)
RS485 info (how it works and spec. & pin outs)
RS449 info (how it works and spec. & pin outs)
RS530 info spec.
V.35 info (how it works and spec.& pin outs)
IEEE-488 info (pin layout)
USOC Codes
Cable Pin Out Diagrams for a lot of different cable hook ups