The Mega CD (1 or 2) is region locked. Unlike the Megadrive, the region check is not done in hardware, but directly in the BIOS. It means that all MegaCD are (almost) identifcals but a different BIOS has been installed for each region (EUR / USA / JAP).  There is basicaly two ways to get another BIOS : loading one from an everdrive or replacing the original BIOS by a region free one. I have at least one game that does not work with a BIOS loaded from an everdrive : “Soul Star”. Moreover, I find it more convenient to launch CD games directly. IMHO, the worst BIOS version is the EUR because it is locked at 50Hz. The JAP one is told to be “the best” because it is said to have some unique features / API needed for some JAP games, but I do not know any game in that case. So The best option seems to be the USA version with its english text menus.

This is the story of my modded EUR MegaCD 2…

Required tools

• Obviously, a MegaCD (2) from any region
• A region free BIOS, can be found on ebay for around 10 euros (basically, it’s an cheap M27C1024 eeprom with a flashed BIOS from the internet…)
• A 40 pin DIP support if not provided with the BIOS. This is optionnal, but allows to later change the BIOS without any soldering
• A desoldering pump : this mod is not that easy without such a pump

Open and locate the BIOS

The MegaCD is pretty easy to open : remove 6 skrews as well as the metal plate and it’s done.

 

The BIOS is soldered on the motherboard : to remove it, the motherboard must be taken out. This implies to unskrew the metal shield and to remove to the 2 skrews that are on both sides of the megadrive connector.

Install the region free BIOS

The Bios has to be unsoldered from the back of the motherboard :

The easiest way to properly desolder the chip is to first add fresh solder to all pins. Then use a desoldering pump to remove all solder fom each pin. I had to redo the operation for 2 or 3 pins before I could remove the BIOS

At this point, the hardest part has been done, soldering the support is easy : ust be sure that every holes are clean, push the support on the motherboard and solder each pins

It’s almost done : the region free BIOS can just be pushed in the support. I had to twist a little bit the legs of the eeprom to make it feets properly:

Result

The BIOS loads 😉