RS-232
Introduced to me at Enlighted.
Basically UART.
https://en.wikipedia.org/wiki/RS-232
RS-232 vs TTL communication (was playing with the mapper and trying to understand what it was about)
- https://www.sparkfun.com/tutorials/215
- https://www.seeedstudio.com/blog/2019/12/11/rs232-vs-ttl-beginner-guide-to-serial-communication/