ZX Spectrum: Experimenting with 1-Bit Sound

The author implemented multichannel 1-bit sound on the ZX Spectrum, enabling chord playback by driving the beeper with timed on/off pulses. By exploiting the Spectrum’s ~1 MHz memory access, a 16 kHz 1-bit PCM stream can be produced using 2 KB s−1 of data, while pulse-width modulation offers higher fidelity despite the speaker’s binary nature.