Here’s a really neat project that plays audio out of a PC serial port running Linux. It works by resampling audio to the baudrate of the serial port. Some comments on the site point out that this is a lot like the old days of TRS-80s, TI-85’s and Sinclair ZX’s when you wanted to get audio out of them. [via] Link.
HOW TO – get audio output on RS-232 (serial port)