GoKawiilDeveloper squeezes hi-fi PCM audio out of ZX Spectrum's 1-bit beeper
A developer completed a project demonstrating high-quality digital audio playback through the ZX Spectrum's basic 1-bit beeper speaker, present on every model of the machine. The technique was verified working on original 48K hardware, a modern Omni 128 clone, and multiple emulators including Fuse, EightyOne, Zesarux, Spectaculator and Clock Signal.