Sega Saturn Region Free BIOS

I just cracked open a 64 pin Saturn to install a replacement BIOS into and have found that this motherboard is labeled "VA SD". The appropriate mask rom seems to be on the underside of the board as opposed to the top and has some slightly different soldering on each pin of the 4 corners.

Not sure if I want to continue to remove the chip and install a new one yet, my gut feeling is that it might not work for some reason. This time I won't be using chip quik and won't be able to easily reinstall the stock mask rom.

Serial # is: 065057549.

EDIT:
DAMNIT! The bloody mask rom is glued down well. I've tried to pry it off (gently) with a few screwdrivers but I'm afraid I'll just sever a few dozen traces or lift a layer of PCB off. Wonder if I could use a heatgun to loosen the glue. Anyone have any ideas?

EDIT deux:


This actually worked (yes this image is missing the GND and VCC wires). Problem is the VA SD model has the chip on the bottom as stated earlier and these wires aren't flexible enough to allow it to be pressed down at all. Result: it won't fit in the case. I'll have to pull the wires back out and swap them with 30AWG.

Really I wanted to make sure it'd even work before I bothered to do it more professionally. Now that I know we can all laugh at my funny picture.

EDIT 3:


Yep this worked too, and fit inside the case completely closed up. Wheee! Hopefully I won't have to go this far with 64 pin #2.

 

If you were a Saturn would you want this surgery?

 

Not if I was a VA5 like the above. :nod:

Honestly I know its a terrible job but I lack the experience to improve upon it much more. What I should have done was to piggyback the Macronix flash on the original mask rom and lifted the appropriate pin driving one high, the other lower and engaging the flash only. Would've been much easier, prettier and far more stable.

All future installers have been warned!

 

So... My first Saturn to attempt is a PAL VA0 with dip bios chip. Which typically I do not have.

Is there any info on pinout? is it the same?

If anyone has any good links to info about saturns (pinouts, schematics, etc) please post some

Also, could someone please explain how you work out the board revision from the serial number?

edit:

Page 2 - 27C160 for dip and pinout is the same.

The rest still stands tho

 

x

 

Links at all?

And I notice earlier in the thread you seem to know how serial relates to board revision... could you share that too?

Thanks

 

Worked on the VA5 I worked on (molested?) above.

Also:
http://www.megaupload.com/?d=07RHS2RB

I can't test these on an actual Saturn (and don't have an emulator handy) but they should be v1.00 NTSC-U and European BIOSes patched in the same manner as the Japanese one used thus far. Remarkably easy to patch as well, only a handful of bytes and the hex values leading up to and away from the patched offsets are identical across all three regions.

It seems there might be a bug in using the 1.01 Japanese BIOS on American Saturns. I've installed these chips in 3 Saturns so far and two of them have been booted at some point to find that the audio is heavily distorted to the point of just short of being recognizable as sound and not pure noise.

Both times were resolved, one by pulling the screw from the grounding strap on the optical assembly then reinstalling it after it cleared the issue (with the issue not cropping back up). The other was supposedly tracked down to a ribbon having popped out during transit on the modboard which seems unlikely as it booted a disc at least once. Might be sporadic, might be technician error.

Anyone else have something similar happen after installing one of these using the Japanese BIOS?

 

Ok,

I have done a couple of these now...

Hot air rework station = glue is no problem. Chip will come away with little force once the chip is heated up (which happens anyway as you are removing).

Rosewood's issue = the replacement chip used is actually wider than the original maskrom, this means you do not have much pad exposed under the legs of the chip. My first attempt looked perfect but wouldnt boot. Removed the chip, applied a little solder to each pad, then placed the chip onto the pads. Heated up with hot air rework and the chip dropped onto the pads and were soldered in. Then hand soldered the legs as I would usually = works perfectly.

this is probably why replacing the original chip worked fine for him - the pads are exposed and much easier to make a reliable joint.


If you dont have a hot air rework station, my 2 suggestions would be:

Try the above method anyway, but make sure there isnt much solder on the pads and its quite flat/even. When soldering to the legs as normal, the solder below should melt and connect too.

Or

When you line up the chip with the pads, make it slightly shifted to the left or right (only a tiny bit, but enough so you can see some pad). this should allow the solder to contact the pads easier and give you a decent joint.

 

x

 

Many thanks.

I actually found the links on here via google yesterday, but the site was down for maintenance and I then forgot.

 

Here is a picture of my install on a VA1 (chip also on underside of board) that had glue:

 

Wow that looks really neat and clean.

 

I'm a bit of a perfectionist - I do not like messy installs/mods.

Also, right tools for the job helps a great deal.

 

I have a MK-80200-50 (oval buttons, Version 1.01a BIOS) that's hard modded to 60hz and JP jumpers.

Not sure what board it is, should the BIOS just drop right in then?

I'm planning on lifting all the legs on the existing BIOS, making sure that each pad is clean, tinning each leg and slowly connecting each point. Hopefully no glue will be involved.

 

Long as its not a VA0 (as thats a DIP chip), yes.

You seem to have taken my advice into account, you should be fine doing it like that.

 

I received 2 bios, here they are:

I know this quote is not for me but it help.
I don't flash bios by myself, a French cartmodder do it for me.
I asked him to byte swap it and said it was done.
1/ I'm not very good in English but by saying "mirrored the bios", do you mean soldering 2 bios together and select one by switch?

I wish to install the region free bios on this Saturn and remove the old one:
]
Many pics of it here (30Mb).

It seem to be a VA PAL SD (va5).
It feature a Modchip:


It has Frequency and region switch:


My goal is to install the region free bios, keep the modchip and the frequency switch.
I will leave the old region switch internally or remove it if necessary.

To do this I have questions:

2/ Is it possible?

3/ I don't know where on this motherboard is the original bios. I think it is here, am I correct?


4/ I see on this post that there are pins to solder on +5V and GND, can somebody show me the way to do it on my motherboard?

5/ Do I have to fix back to original the region switch or just leave it this way?

I know this is many questions in a raw but I'm a kind of noob.
Your help will be very much appreciated. ^^

 

1.) Mirrored - this means the same file is copied multiple times to fill the chip. The original bios is 512KB and the chip I sell is 1MB (and the DIP chip I got was 2MB) which means for the 1MB chip you have the file twice and for 2MB its 4 times.

2.) Yes, thats possible and is what you want to do.

3.) yes, that is the bios

4.) The DIP chip you have is going to be harder to solder in than the replacements I sell - you will need to wire to chips legs to the pads. You need to get the datasheet of the bios I sell and the datasheet of the chip you have bought. Then wire up the legs to match. You should have bought the chip I sell as it would have been much more simply. As you are using an EPROM and not flash - you do not need to do the same wiring to the chip. You just need to connect extra address lines to ground.

5.) set the jumpers back to original or hard wire the mod internally.

 

x

 

1/ Thanks, it's clear.

2/ Woot and yes.

3/ Perfect.

4/

I can do it I think.

I don't understand very well why I do need your chip, mine is burned with the bios inside and byte swapped.
I mean I can buy you one if it is necessary but it don't seemed by reading dForce3000 on his website, I must miss a point...

Source

I whish I could do that only with my eprom like dForce3000:

I don't know if we understand each other on my eprom, maybe you were thinking it was not burned with the bios inside.
If my eprom is good to go, as the pinout seems to be simmilar to the original Bios maskROM, wich pin is the extra address line to connect to ground, if I'm thinking right...

Finally, it seems more difficult than just solder 20 wires from the eprom in the same order as the original bios.

 

@Druid II: I'll see if I can simply remove this region switch and bring my Saturn back to normal.
I did not make this switch so I must check if it is independant from the frequency switch first.