ZX81 with music: The Sound Demo by HOOY-PROGRAM

ZX81 is a Sinclair Research computer released in 1981. It has no sound, 1Kb of memory, and black&white (monochrome) graphic in hardware resolution 64x48 pixels. BASIC is its main operating system, working on Zilog Z80 CPU 3,25Mhz. The newest device for ZX81 users is ZXpand invented and developed by SirMorris and being sold by RWAP Software. The ZXpand gives to our ZX81: - 32Kb of RAM, - flash (instant) loading/saving of programs, - SD card as an easy data-transfer with PC, - sound of AY chip (nowadays