Abstract: A multiple peripheral interface to a computer serial port includes a microcontroller with an adapter serial port for coupling to a standard serial port of a common type of host computer or terminal, a plurality of peripheral ports having read/write configurable data lines for coupling to devices of a process, and a central processing unit interfaced between the adapter serial port and the peripheral ports and executing an adapter operating program to translate simple letter commands and numeric values received from the host computer to port configuration commands, port read commands, and port commands and to translate data read from the peripheral ports to numeric values for transmission back to the host computer.