nipkow ‐ play digital audio from VIC-20 tape
The first home computers came with music cassette drives instead of disk drives as the latter were just too expensive for the consumer market. These tape drives can basically let you detect the time passing between two pulses. With the help of pulse‐width modulation "nipkow" plays 4-bit tunes from tape in real‐time at 4kHz. And, yes, I'm glad that I was the first one to come up with this. The player has been used for the splash screen music of "PULSE".
Video on youtube.
Demo on pouet.net.