Progress December I - More silicon nudes (Patreon)

Guesswork does get elements to function individually, but piecing them together often reveals that they're not that accurate because they don't stick as a whole.

I was bitten by this more than once in this project mostly because phases of different signal groups didn't match. Checking signals multiple times to see if I wasn't hitting an unknown corner case or if I messed up while taking notes or naming files.

Frankly, most of the time, the notes were correct and I was just taking wrong guesses (often overcomplicating things). This back-and-forth work pattern isn't very efficient and some doubts still aren't cleared, so what can be done to avoid guessing from outside the chips ? Not a whole lot of options except seeing inside.

After failing at decapping chips with nitric acid more than a year ago, and knowing I couldn't ask a company to do it without having to spend thousands, I either had to resort to acquaintances (who have other things to do) or to myself...

Turns out that I found a source of concentrated sulfuric acid, tried it again, and it worked ! Decapping chips for imaging with $30 worth of tools and chemicals, cool.

The next step (which is imaging), involves a bit more than $30 unfortunately, so I still can't do the whole job by myself. John McMaster, who decapped AND imaged the YM2610 last time, accepted to take pictures of the most important die, which is the one from the LSPC (Line SPrite Controller). I'll see later if the second graphics chip (NEO-B1) needs to be imaged also, or if I can get enough infos from the LSPC pictures to figure out the rest.

Finally, I must say that I'm quite excited about this since John recently published pictures of Sega chips from the same series (Fujitsu CG24 gate arrays) and the gates can clearly be seen and understood with minimum inferring as there are only 2 metal layers. It will take time, but I'm confident it can be done.

As Patreon didn't roll out their "great" idea about fees, and as I wish to forward the pledges to John for his work, I'm making this a paid post. I'll post pictures and screenshots showing the process of tracing out gates and turning them into verilog. This post's pictures are from my hacked-up microscope, can't do much with those.

Some of his previous work: https://siliconpr0n.org/map/

Thanks for the support, be it here or directly by Paypal :)
And thanks, Dad ! :D