This is cool, but doesent even seem to mention the ScreamTracker pc speaker hack. Maybe it was done the same way, but it was able to output about 8khz bandwidth, 1 bit rendered and anti-aliased from 8 or 16 bit sound samples to the pc speaker. It worked so well I still have tape recordings I made with a hacked up rca plug attached. The paralell port adapters sounded better, but had their own neat lofi sound. About the best you could do without a sound card, which were stupid expensive back then. It was a far cry from the 'musical' beeping I was used to.