One-bit music - the music written for the simplest sound device used in computers until the mass of sound cards. Capabilities of the device are extremely small. Controlled through port increments only 1bit. However this did not stop the musicians to write masterpieces.
At the current music scene is represented by a one-bit music creations for the ZX Spectrum Beeper. Among the early masterpieces worth noting the work of Tim Follin (Tim Follin). The most active musicians of the contemporary scene is a one-bit Mister Beep