Loïc *WydD* Petit deep dives into the reverse engineering of a classic arcade board: Street Fighter II New Challengers.

Schematics are useful in repairing systems, but it is also useful for the emulation community whose aim is to simulate how game boards work in order to play those games on modern hardware. The CPS2 has decent software emulation programs but these are not 100% accurate and lately, people are performing more and more hardware emulation which would definitely require schematics.

Unfortunately, on this board, Capcom chose to use five custom-made integrated circuits. On older arcade boards, you often have well-known core components (processor, memory, sound…) bundled with a lot of very well-known basic chips, all wired together to create the final board. However, having custom chips allows more compact designs, and also allows to obfuscate and add security measures to avoid counterfeits and bootleg copies of the game. This was actually proven to be effective as no bootleg boards of CPS2 games have been created. But, this makes the process of understanding the board more complex because obviously, no datasheet exists for those custom chips.

This will be our goal in this article. We are going to try to understand what does one of the chips, the DL-1827 portrayed in the picture above, by looking at its internals and analysing how it is structured.

See how the gate array is painstakingly decoded, gate by gate. Read more.