Demo Unit II

From Sega Retro

Demo Unit II
Made for: Sega Master System
Manufacturer: Sega
Release Date RRP Code
Sega Master System

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Demo Unit II (Model No. 3087) was an add-on for the Sega Master System used for advertising the SMS in shop windows and/or demo cabinets.


Five standard Master System ROM cartridge boards (any region) can be inserted into slots inside of the unit, and an integrated TI 555 timer chip allows the unit to automatically switch between the different games at a set interval (controlled by a yellow pot knob on the unit's motherboard). The unit connects to the SMS via the Power Base's expansion slot, which also delivers the necessary power from the SMS to the Demo Unit II.[1]

This was essentially the SMS-compatible predecessor to the Mega Drive's Demo System DS-16, in that it's a multi-game switcher with a built-in automatic timer functionality for demonstration purposes that needed to be tethered to the original console via the expansion slot to function. The Demo Unit II has one less game slot than the DS-16 (five instead of six), no external cartridge slots, and no manual external button to switch the active game. It was only available to retailers, primarily in the European & Japanese regions.

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