Region Free BIOS (Sega Saturn)
The Sega Saturn has a BIOS that locks it to specific regions. Replacing this BIOS with a region-free BIOS allows you to play any region games.
You can purchase the Region Free BIOS chips from us here.
There are 2 kinds of BIOS chips, a much rarer DIP (through hole) chip on early revisions, then a much more common SOP (SMD) chip. I will cover the SMD here, but the install is identical just with the different sized chip.
The original BIOS is the TCS74200D, usually labelled IC7 and typically at the front right of the motherboard sometimes on the top and sometimes on the bottom.
The goal is to replace the original BIOS with the region-free BIOS, but it is not quite a straight swap.
The new chip has 4 more pins than the original, meaning you have to solder in the new chip with the top 4 pins hovering over the edge with no connection, and then hand wire them after.
Simply put:
- Pre-bend pins 1/2 and 43/44 (the top 2 pins on each side) up in the air
- Solder the new BIOS in place so that the extra 4 pins at the top are floating in the air
- Solder the top left 2 pins (pin 1 and 2) to ground
- Solder the top right 2 pins (pins 43 and 44) to VCC.
What we are doing is setting the Ready signal on the new BIOS to ground, and the !RESET And !Write Enable to 5V keep it out of reset and not in write mode.
Some BIOS chips are 512k, some are 1MB, so pins 1 and 2 are either:
- Pin 1 Not Connected
- Pin 2 Ready
Or:
- Pin 1 Ready
- Pin 2 Address 18 (for 1MB)
So to make sure it works on both, we simply solder both pins 1 and 2 together as both will be grounded anyway.
Solder pins 1 and 2 to ground, and pins 43 and 44 to VCC (5V).
