Is it after a monitor with 9 pins, or a serial terminal?
A lot of the consoles of the era used serial terminals (aka dumb terminals) instead of a monitor. What you can do, if it is serial, is use any computer with a serial port (or a usb->serial converter) and then run a terminal emmulator (like HyperTerm).
Finding antiquated hardware is difficult, as they tend to be used to the point of death, then thrown out, or are neglected in the corner of a storage room for years until they decide to do a clean-out (meaning they are often dead).
You may have better luck building an adapter (I am sure there are specifications for the cables out there on the net - maybe even a pin-out guide to build an adapter)