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Mark III FM Power Base Converter Prototype

posted Dec 4, 2014, 12:15 PM by René Richard   [ updated Dec 4, 2014, 12:23 PM ]
I wanted to be able to use my FM Power Base Converter design with Mark III games (the Japanese Sega Master System, more or less). The trouble is, the Mark III, while it runs practically the same software as the Master System, used a different connector for its game cartridges. The Mark III uses a 44 pin 0.125" edge connector while the Master System uses a 50 pin 0.100" edge connector.

Before I invest time in branching a FM Power Base Converter design to a Mark III edge connector, I figured I should first try to get it working by hand-soldering a 44 pin 0.125" edge connector to one of my FM Power Base Converters. 

This was "almost" as simple as connecting the same-named signals together. There was however a few exceptions.

On Power Base Mini and FM Power Base Converter:
  • Genesis_A16 -> SMS_A15
  • Genesis_CE -> SMS_M07
On M3 Power Base Converter prototype
  • Genesis_A16 -> nowhere
  • Genesis_CE -> M3_A15
I used a board that I am currently developing to interface the Mark III edge connector to the SMS edge connector. I solder all of the connections in a very "ratsnest-y" method and what do you know - it worked!

I have to thank the great people at SMSPower.org, specifically in this thread, which provided very good information about some errors in online Mark III pinout documentation. 

Now that I have a proof of concept, I'll start a branch of the FM Power Base Converter to support Mark III games. What's nice about this is that, because the Megadrive/Genesis doesn't use a BIOS like the Master System, there should be no issues with play any/most of the Mark III library on Megadrive/Genesis. Hooray for imports!

You can get a suitable Mark III edge connector from Sullins, part# EBA22DCTN.