Until V7.1 OpenVMS knows the two built in serial ports as TTA0, and
OPA1. Unless you have booted with an alternate console in which case
they are OPA0, and TTA0. As of V7.1 they will be TTA0, and TTB0 unless
you use an alternate console. In that case they will be OPA0, and
The easiest way to determine the device name of any particular serial port
is to plug a terminal into it and log in. SHOW TERMINAL will tell you the
Serial ports are typically called TTAx, OPAx, or TXAx.