Monday, October 21, 2019

Let's do two more this month

Caius contacted me about two 8751H mcu's which  Jorge Silva would borrow us for decapping.
The package arrived today and i took a quick lookat them.


This game is inside MAME since December 1997 and while the game-emulation works, we had no chance to preserve the MCU the last 22 years.
The MCU got decapped today and completes this romset!


Dumped in March 2000, this is another game which works in MAME since years. And finally today we got the MCU decapped for it!
Another game fully preserved!

Interesting fact:

The dump of "Air Duel" has this at the very first lines:

Whatever "Last of Ninja" is...

EDIT 21-10-2019: Maybe it's from "Ninja Spirit", a game which was released two years earlier (1988) from IREM and they had some MCU's of it left, which they recycled for "Air Duel".  As "Ninja Spirit" is missing it's MCU dump too, we will try if this dump also works for it. 

EDIT 22-10-2019: "Last of Ninja" is really the name of "Ninja Spirit". The MCU-dump is working perfectly for "Air Duel" and it really looks like IREM was just too lazy to remove the wrong game-title from it. This dump will not work with "Ninja Spirit".

Thanks to Caius and Jorge Silva for helping to preserve these games!

Sunday, October 13, 2019

Final MCU's from Brian's package

and here we have the last three MCU's of Brian's last package.

Body Slam

Matches the existing decap of it! So this is another confirmation of the decap and practice for my decapping skills.

Fire Trap (US)

This is the MCU for the US-Version of Fire Trap. (The Japan-Version was decapped a couple of weeks ago).
It does not match the handcrafted dump! So this is a new real dump!

Last Mission

So this is really interesting!
As i already decapped this chip about 6 weeks ago already, we got good reads from it back than. Now i decapped this new chip and got a different dump.
While the rompart of the chip is the same on both and matches each other, there's a difference in the empty-part of the rom:

LEFT: old decap
RIGHT: new decap

both dumps will work on the real hardware with no difference, as this is only in the not used area of the rom.
Basically the second dump is cleaner and this way looks "more" correct to me.
As i have the "old" mcu here too, i redumped it a couple of times today and always get the same rom. So they are really different in that area.

Friday, October 11, 2019

why decapping MCU's is so important

Got the next two MCU's from the lot in my hands. Those two proved, why it's so important to decap and secure MCU's, as Emulation-Simulations of the MCU's won't help you to rescue your real board.

Image Fight

I test all MCU's about PIN-connections before i start to decap it. to be sure that the MCU is at least "working" before i put my hands on it.

So i put the MCU in my programmer and got this:

No matter what i did, nearly all pins on the left side had no connection. Only GND had a connection, so i cleaned all other pins, tried again and got the same result.

So i started to open the chip. As it was already dead, i had nothing to loose. I checked the die with my bare eyes and didn't see any faults. So i put on some nail-polish and afterwards made the first pictures of the die with my microscope.

Look what i found:
Can you see it? Two wires are cut.
Now to the interesting thing, this is GND!!!

As i  don't have the equipment to fix this small wires, and solder those back together, i made my own little fixing-tool for it:

When i connected the two wires, i got connections to all pins and could read the mcu.

Sadly the dump matches the existing Image Fight (Japan) dump. As we didn't know for which region this mcu was, we were hoping it is for the missing World revision.

At least it was a great challenge. I'm pretty sure someone mixed up VCC and GND on the board and that's why these two wires got blowed up.


Brian already told me, before he shipped this package from the US, that one of the MCU's is missing many pins.
It was the MCU for Quartet and many of the pins got corroded and really broke away if you just looked at it.
After a short fixing job it at least looked like this:

The other side did look nearly the same, so basically about 20 of the 40 pins were at least partial missing.

The decap and Pin-fixing job worked out and it got constant reads after erasing the lock-bit.

Another mcu preserved!

MCU challenge

Another package from Brian arrived today!

Brian drove about 400 miles (or 650km) to a guy who borrowed us these 8751H chips for decapping. I had some time today and started with the first 3 MCU's from the lot.


Finally this MCU is now secured! I already tried it in MAME and it looks like it's working flawlessly. So the handcrafted dump can now get removed.

CHELNOV (US) (Data East)

And here's another MCU dump for Chelnov. This time it's for the US-Version. Interestingly, this dump does not match the handcrafted rom. Will be interesting, what's the difference.

Dynamite Dux (set 1) (8751 317-0095)

Now also this set is completely secured and preserved.

Enjoy another batch of 8751 MCU dumps for MAME. More will get decapped soon...