15 Nov
2014
15 Nov
'14
7:58 p.m.
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