3 ms·

> Some of the reverse engineering tricks utilized by DiscoStarslayer include chemically decapping the CXP102064 to expose the die, then using microscopes and op

> Some of the reverse engineering tricks utilized by DiscoStarslayer include chemically decapping the CXP102064 to expose the die, then using microscopes and optical dumping skills to analyze the silicon chip circuitry. In this case, a lucky break during the hacking apparently uncovered an exploit that provided a method whereby the chip’s data could be extracted through software. This is next level commitment to the cause. Also, I can totally imagine their reaction when they discovered the exploit and realized they could put down the ... chemicals. XD

piltdownman 16d ago
Byuu and McMaster decapped all the SNES ones with amazing write-ups a number of years ago.
- delinom 16d ago
  I am aware of their collaboration, but where can I find these write-ups?
spicyjpeg 16d ago
There actually is a pretty large community of hardware reverse engineers decapping chips for fun, sometimes just to dump internal ROMs (like in this case) and other times going as far as to try reconstructing the original schematics and netlists in order to document the chip's internals and allow for more accurate emulation, in some cases all the way down to the transistor level [1] [2]. If you want to learn more, Ken Shirriff has written a lot of blog posts on the subject [3] and Siliconprawn [4] hosts a huge collection of die shots from many contributors. [1] https://floooh.github.io/visual6502remix https://floooh.github.io/visual6502remix [2] https://github.com/iaddis/metalnes https://github.com/iaddis/metalnes [3] https://www.righto.com/ https://www.righto.com/ [4] https://siliconprawn.org/ https://siliconprawn.org/
- darkfloo 16d ago
  Doesn’t decapping chips require hydrofluoric acid ? If so I cannot express enough respect, the one person I’ve interacted with that regularly worked with it put the fear of god with by showing what one insignificant miss for anything else did to his finger
  - monocasa 16d ago
    No, the default acid used is nitric acid. Which should definitely be treated with respect, but isn't nearly as nasty as anything with fluorine. But if you have a few examples of the chip and can break a few eggs to make an omelette, there are techniques that just involve hitting the epoxy with a blow torch and/or opening it up with plyers.
    - joshumax 16d ago
      Not just regular nitric acid either, but red/white fuming nitric acid in many cases! Back during my teenage years I used to make the stuff for decapping projects and amateur rocketry by grabbing the ingredients from our local hardware store and distilling it in a make-your-own-moonshine kit I bought off of craigslist. Worked great up until the police were called because the store employees thought I was making bombs. I hear heating up sulfuric acid is the better way to decap epoxy chips nowadays.
  - gosub100 16d ago
    A careless move with a skill saw can take your finger off too. I don't think acid deserves such a scary reputation. I guess because it doesn't make an obnoxious sound does make it easier to forget. But in both cases you must follow best practices (fume hood, goggles, bicarb wash nearby) , and suffer consequences if you don't.
    - kadoban 15d ago
      > I don't think acid deserves such a scary reputation. Acid in general can be handled quite safely with the right mindset and equipment. HF is _fucking_ terrifying though. Even many professional chemists (or maybe especially pros?) won't work with it. It's far beyond just being dangerous to your skin and eyes. Bicarb and goggles sure won't cut it as safety procedures.
- ZenoArrow 16d ago
  This book may also be of interest: https://nostarch.com/microcontroller-exploits https://nostarch.com/microcontroller-exploits
returnorthrow 16d ago
This has been done for many years in the arcade preservation community, allowing specific arcade boards to be fully documented and preserved in MAME and now MiSTer. Specifically Guru’s ROM dump has documented decap efforts since 2007 it looks like.

piltdownman 16d ago

Byuu and McMaster decapped all the SNES ones with amazing write-ups a number of years ago.

delinom 16d ago
I am aware of their collaboration, but where can I find these write-ups?

spicyjpeg 16d ago

There actually is a pretty large community of hardware reverse engineers decapping chips for fun, sometimes just to dump internal ROMs (like in this case) and other times going as far as to try reconstructing the original schematics and netlists in order to document the chip's internals and allow for more accurate emulation, in some cases all the way down to the transistor level [1] [2]. If you want to learn more, Ken Shirriff has written a lot of blog posts on the subject [3] and Siliconprawn [4] hosts a huge collection of die shots from many contributors. [1] https://floooh.github.io/visual6502remix https://floooh.github.io/visual6502remix [2] https://github.com/iaddis/metalnes https://github.com/iaddis/metalnes [3] https://www.righto.com/ https://www.righto.com/ [4] https://siliconprawn.org/ https://siliconprawn.org/

darkfloo 16d ago
Doesn’t decapping chips require hydrofluoric acid ? If so I cannot express enough respect, the one person I’ve interacted with that regularly worked with it put the fear of god with by showing what one insignificant miss for anything else did to his finger
- monocasa 16d ago
  No, the default acid used is nitric acid. Which should definitely be treated with respect, but isn't nearly as nasty as anything with fluorine. But if you have a few examples of the chip and can break a few eggs to make an omelette, there are techniques that just involve hitting the epoxy with a blow torch and/or opening it up with plyers.
  - joshumax 16d ago
    Not just regular nitric acid either, but red/white fuming nitric acid in many cases! Back during my teenage years I used to make the stuff for decapping projects and amateur rocketry by grabbing the ingredients from our local hardware store and distilling it in a make-your-own-moonshine kit I bought off of craigslist. Worked great up until the police were called because the store employees thought I was making bombs. I hear heating up sulfuric acid is the better way to decap epoxy chips nowadays.
- gosub100 16d ago
  A careless move with a skill saw can take your finger off too. I don't think acid deserves such a scary reputation. I guess because it doesn't make an obnoxious sound does make it easier to forget. But in both cases you must follow best practices (fume hood, goggles, bicarb wash nearby) , and suffer consequences if you don't.
  - kadoban 15d ago
    > I don't think acid deserves such a scary reputation. Acid in general can be handled quite safely with the right mindset and equipment. HF is _fucking_ terrifying though. Even many professional chemists (or maybe especially pros?) won't work with it. It's far beyond just being dangerous to your skin and eyes. Bicarb and goggles sure won't cut it as safety procedures.
ZenoArrow 16d ago
This book may also be of interest: https://nostarch.com/microcontroller-exploits https://nostarch.com/microcontroller-exploits

returnorthrow 16d ago

This has been done for many years in the arcade preservation community, allowing specific arcade boards to be fully documented and preserved in MAME and now MiSTer. Specifically Guru’s ROM dump has documented decap efforts since 2007 it looks like.