Operator's Guide B-13
First, the Signal Ground on the printer is tied to the Signal Ground on the
IBM PC/AT; likewise, the Frame Grounds on the printer and IBM PC/AT
are tied together. Next, RxD on the printer (Pin 3) is tied to TxD (Pin 3) on
the IBM PC/AT; then TxD (Pin 2) on the printer is tied to RxD (Pin 2) on
the IBM PC/AT. Lastly, the control signals are connected: DTR (Pin 20)
on the printer to DSR (Pin 6) on the IBM PC/AT, and RTS (Pin 4) on the
printer to CTS (Pin 8) on the IBM PC/AT.
IBM PC/AT to Printer Wiring Diagram AB0-AP