When I was a kid, my first PC was a pretty crummy 4.77 MHz XT. Some of my friends were very cool and had fast AT machines with sound cards (mostly Sound Blasters), and I was very envious, especially when my friends and I discovered MOD files (tracked music).
MOD files originated on the Amiga computer, I believe, and allowed you to play complicated multi-track music on low-end PCs by mixing different samples of instruments, voice, etc. and doing clever things like changing the pitch. Some of the MOD files were very impressive, especially those by a tracker call U4ia. A blog post I stumbled on has some basic info about him, and reminded me about the first MOD-playing program I used - ModPlay.
By then I had upgraded to an AT machine (one with a Turbo switch - "Who would want to ever turn that off", I wondered?) ModPlay could play music through the PC speaker, but the quality was not very good, and at the time I couldn't afford to buy a Sound Blaster card. Luckily for me, ModPlay came with instructions on how to build your own simple D/A converter, which connected to the parallel (printer) port. For the cost of a few IC's, resistors, and capacitors I was able to build a pretty decent 8-bit "sound card", which I hooked up to the cheap "all-in-one" stereo we had at home. The sound was incredible - better than most of my friend's sound cards! :)
I was interested to see that the author of ModPlay (also named Mark) now works as a Security Response Lead at RedHat. That's pretty similar to what I do now, so once again the Web leads around in strange circles...