Sega Saturn Region Free BIOS
After many years, a region free BIOS for the Saturn has been released. Currently it does not let you play CDr discs or control video mode, but it’s still a fantastic achievement. For further details check out the the site which released it, and assemblergames for a big bunch of info.
Bad_Ad84 has pointed out that it’s probably easiest to get GND and VCC from other legs on the same chip, so – link up leg 2 to 13 (GND), and legs 43 and 44 to leg 23 (VCC). You can also buy a pre-programmed chip from assemblergames, courtesy of (again!) Bad_Ad84, making this a very very easy mod.
Here’s how I removed the existing BIOS chip (IC7 on the couple of boards I’ve looked at). I don’t have a hot air station anymore, so I used a pair of half decent side cutters to carefully snip each leg. I hold them with the flat side facing upwards so that the sharp edge is as far away from the motherboard as possible and then cut each leg as close to the chip as I can (you’ll probably find it will cut on the bend of the leg, that’s perfect!)
Work you way along both sides and double check them, you definitely want a clean cut through each leg for the next bit! In fact, TRIPLE check them.
You may find that the chip is glued to the board and won’t just lift off. If this is the case, you can gently lever it off, be VERY careful not to damage the board if you have to do this, if possible, use something plastic to do this, so you don’t scratch the board or damage any traces.
Now it’s time to tidy up the pads ready to solder the new chip onto. Very quickly run your soldering iron along each pad and the bit of remaining leg should come away with it. You can probably do a couple at a time and then wipe them off on a bit of wet sponge.
The new chip is a tiny bit wider than the old, so make sure that the solder on the pads reach the end so that you get good contact on each leg you solder on next. If necessary, add a small amount to the pads, you don’t want lots on there though – I do this by holding the soldering iron on the pad, and then just quickly touching it with some solder, you can easily control how much gets added to the pad this way by lifting the solder away when ready. You can’t really see it too clearly in the following photo, but there is more solder there!
Now it’s time to prepare your new chip, straighten out legs 1, 2, 43 and 44.
Unfortunately I forgot to photograph that I added a tiny bit of solder to each leg. I place the chip upside down, had drop of solder on the iron down and touched each leg with the iron to transfer a small bit of solder to it. You only want a tiny bit on there!
Hold the chip in place and solder just one of the corner legs. Make sure that the chip is completely straight and that the rest of the legs line up, then heat up and solder into place the leg on the opposite corner. Now do the other 2 corners and the chip will hold itself securely in place ready for you to solder the remaining legs.
The photo above shows that I’ve completed the first 5 legs. The red arrow is where I put my soldering iron to heat up the leg and the solder, I gently push it in the direction shown to push the leg down onto the pad properly. Work your way along, taking your time to do each leg.
That’s all the legs on one side completed :-) Finally it’s time to provide power and GND to the new chip. Bad_Ad84 pointed out that it’s possible to power it from other legs on the chip – so link up leg 2 to 13 (GND), and legs 43 and 44 to leg 23 (VCC). You can see I chose to use one side of a nearby capacitor which is linked to leg 13, I could have done the same for leg 23 which is also linked to a capacitor nearby. Leg 1 ISN’T connected to anything.
Switchless Video Mode Add-on
I also did a small re-write of Sebs switchless Saturn mod code, so that you can use it to control just the video mode and reset the console. You don’t need to wire any of the JP points obviously, just power, LED, reset, button and video mode legs of the 16F630. Press the reset button quickly to reset, hold to cycle through video modes and release when LED is Green for 50hz, Red for 60hz. Here’s a few photos to show how to wire it in, it’s basically the same as wiring up Sebs original Switchless Mod, but with less wires!