Shponglefan wrote on 2025-03-12, 21:32:

I have a monitor with a 9-pin port for CGA/EGA. I'm wondering if I can use an RS232 serial cable to connect it to a CGA or EGA video card.

Not sure if there is any different in pinout or wiring depending on the application of the signal from a cable perspective.

A straight 1:1 9-pin cable is good for both serial communication and MDA/CGA/EGA. While most null-modem cables are female-to-female, there are female-to-male "RS232" cables that don't have a straight 1:1 mapping, and those cables are unusable for MDA/CGA/EGA. Furthermore, due to the higher frequencies, shielding is more important for a video cable than for a RS232 cable, but this is more about emitting interference than about preventing of interference disturbing the signal.