For anyone who's curious about it, let me describe the extraction of the ROM for Fidelity Checker Challenger 2. It is not your standard desolder->romchip in reader tool->rom file comes out

A few years ago, Yovan bought Checker Challenger 2 for dumping the ROM. From his PCB photos, we saw it has a NEC UCOM-4 MCU, the CPU is emulated in MAME but it is not easy to dump electronically. Yovan was reluctant to send the pcb to someone else, and a rom dump didn't happen.

A couple of years later (2 weeks ago), I spotted a very cheap one on ebay. Sean Riddle ( http://www.seanriddle.com/decap.html ) and I purchased it and he started working on dumping the ROM.
The dumping process done by Sean:
- delid(decap) the chip, making the bare die visible
- give it a bath in Whink(diluted hydrofluoric acid) to remove remaining goo and the top layer
- put it under a motorized microscope that makes hundreds of photos (this step is also done before the acid bath)
- stitch photos together and end up with a huge picture, I've uploaded a temporary mirror here: WARNING it's 68MB, 16304x18327 https://tsk-tsk.net/net/temp/checkersacid.jpg
- the ROM bits (literally the 1s and 0s) are in the big array at the top left
- use a tool to extract the bits visually, and verify them
- convert to bytes in correct order (the correct ordering was figured out ages ago when a Roland TB-303 MCU was decapped)

The emulation process is same as usual: Sean sent me a pinout/netlist, and I program the MAME driver.
https://github.com/mamedev/mame/blob...el_checkc2.cpp