Epson 4100 manual IBM PC/AT* to Printer

B-12 Appendix B—Serial Interface

When the PC has data to send, it looks for a high voltage input on its Pin 5, CTS, before sending data. The printer actually holds the voltage continuously high on its Pin 4, RTS, which is tied to the PC's Pin 5. Thus, the PC automatically begins sending data on its Pin 2 and continue until all data are sent or transmission is interrupted by a handshaking protocol.

IBM PC to Printer Wiring Diagram

IBM PC/AT* TO PRINTER

AB0-AO

The wiring diagram that follows shows how to connect an IBM PC/AT, a DTE device, to the printer, also a DTE device. It differs from the IBM PC example only in the pin numbers on the computer side. The IBM PC/AT uses a male, 9-pin, D-type serial connector.

*Also 386s, 486s, etc.