Jul 272019
 

Some time ago Team Europe has had success in resetting the security fuse on 8751 MCU’s.
See these posts
Post 1
Post 2
Post 3

While looking for something else among my own hoard of stuff I came across an old Choplifter PCB that has been used over the years for parts but the MCU was still present.
Inspired by the work of Team Europe I decided to give it a go myself.
Removing the cap was a bit tricky because I don’t really have the tools required for the task. I ended up using a small file and making a lip so I could fit a screwdriver under it and pry the lid off.

Adding some nail varnish generously donated by my daughter and we have this familiar sight.

I threw it in the UV eraser for 15 minutes and tried reading.
I got data back but was it good?

Comparing to the one currently in MAME I had 1 byte different at address 0x100.
Now, looking at the MAME source we can see that it applies some software patches.

The byte at address 0x100 is indeed on of the patched areas.
Not sure why address 0x27b is also patched. Without this one applied there is no need to compensate by patching address 0x2ff.
Anyway I removed these patches from MAME and booted with my dump and all seems to work just fine. Hopefully the MAME team will agree its a good dump and add it too.

Thanks to Team Europe

 Posted by at 4:18 pm

  2 Responses to “Choplifter MCU dumped”

  1. Awesome work!