MCT Serial board mystery - Can you crack the pinout code?

[tony duell]

> It sounds like you've just about got it figured out though. If you have
> the datasheet for the 1458 (aren't there 1459s on the board too?) then you
> can follow the signals through the level converters back to the UART, and
> its datasheet should then tell you exactly which signals are which.

Are you not thinking of the 1488 and 1489 (commonly used RS232 driver and receiver chips)? The
1458 is a dual op-amp.

Op amps were often used as level shifters in older RS232 devices. I guess that's what is happening
here.

-tony