Sega Master System Converter/Power Base Converter

Summary

In 1985 Sega launched the Sega Mark III in Japan, which appears in the West as the Sega Master System (SMS). With an 8-bit processor and replaceable modules, the console belongs to the 3rd generation. With more than 10 million units sold, it was less popular than the Nintendo Entertainment System (NES), which sold over 60 million, but over 300 games still appear. In Japan, the successor, Sega Mega Drive (Sega Genesis in the USA), comes in 1988. Since the 16-bit successor of the 4th generation is not module-compatible, Sega produced an adapter with which games of a Sega Master System could be played on the new Sega Mega Drive. A console for two generations of games!

The adapter is called Master System Converter in Europe, Sega Genesis Power Base Converter in the USA, Mega Adaptor (メガアダプタ) in Japan and Adaptador Para os Jogos Master System in Brazil. It plugs into the Mega Drive’s cartridge slot and matches its shape, with a hole that leaves the console’s indicator light visible. Its casing does not fit the Mega Drive 2, although the electronics are compatible. Its successor, the Master System Converter II, fits both Mega Drive models but lacks the Card Unit slot for the few games released on Sega Card. Other manufacturers also sold adapters. Sega’s adapter supports both SMS and Mega Drive controllers.

Interestingly, the Sega Mega Drive is in principle already compatible with the SMS, and contains the same central hardware components (Z80 processor and SN76489 for sound/music) and the Video Display Processor supports the old mode. However, the design of the modules is different, so that the adapter does hardly anything different than adjust the shape and mute the 68000 processor in active mode and activate the Z80.