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ADD-ON - Ad - 01.jpg
Developer: Micro Power Ltd
Released: 1982-1?-??
Type: External Device
Slot: Edge connector
Platforms: Platform - ZXS.png

The ADD-ON is an early peripheral for the ZX Spectrum 8-bit home computer. It could be ordered from Leeds, West Yorkshire, England for changing prices. It was advertised for £19.50 since December 1982, then £22.50 since April, and finally £19.95 from July to November. Unfortunately, the manufacturer spelled it very inconsistently. The VGMPF is going with the most common spelling.

The ADD-ON is a board without case. On board are a jack, a 3.5 mm cable, a volume control, three joystick ports (one digital Atari one, two analog Micro Power ones), a 2-watt speaker, and an AY-3-8910 programmable sound generator (with the reset pin accessible to programmers), probably clocked by the Spectrum's 1.75 Mhz. Unlike later competitors, you cannot plug more Spectrum peripherals in.

The jack can be used to play the AY-3-8910 sound on headphones or Hi-Fi systems. The cable can be plugged into the Spectrum's MIC socket to play the "standard BEEP" on the 2-watt speaker. The manual warns from plugging the cable into an output device.

Enclosed were a tape cassette, an 8-page manual dated 1983, plus two pages from General Instrument's manual. Altogether, they offer five examples (Gun-shot, Whistle and gunshot, Bomb, Laser, A day at the seaside), an editor (without saving) named "SOUND EDIT", and a shooter named "JYSTICK DEM".


Release Game Sample
1987-1?-?? Plum Duff (ZXS)

Picture Gallery


Emulation Status

No emulators and players are known to support the ADD-ON, but on games that also support the Fuller Box or 3-Channel Sound Unit, the output is probably identical.