Jotego is officially building a CPS3 core for FPGA

FPGA developer Jotego has officially started work on a Capcom Play System 3 core. According to a recent Patreon update, the initial core files are currently sitting in a private repository. The developer is balancing this new project alongside ongoing work on SETA chipset games and Neo Geo Pocket Color save states.

Capcom released the CPS3 hardware in 1996 as its final proprietary 2D arcade board. The system only ever hosted six games. The entire library consists of fighting games: Red Earth, JoJo's Venture, JoJo's Bizarre Adventure, and three versions of Street Fighter III. Red Earth experimented with RPG leveling mechanics in a fighting game format. JoJo's Bizarre Adventure remains a competitive staple decades later. Street Fighter III: 3rd Strike is widely considered one of the best fighting games ever made.

Six games and a suicide battery

The hardware paired a CD-ROM drive with a complex security cartridge that used battery-backed SRAM. The arcade operator had to install the disc and wait for the game to write its data to the system memory. The security cartridge held the decryption keys. When that battery died, the keys vanished and the game stopped working entirely. This suicide mechanism made original CPS3 hardware a nightmare for arcade collectors to maintain.

Software emulators like MAME have been able to run CPS3 games since the encryption was reverse-engineered in 2007. Hardware-level emulation via FPGA is a different beast entirely. It requires mapping out the exact logic of the original custom chips to recreate the electrical behavior of the board.

Over a thousand arcade boards

Jotego (Jose Tejada Gomez) is arguably the most active developer in the FPGA arcade scene. His JTCores project currently supports more than 1,000 arcade titles. He previously reverse-engineered the CPS1 and CPS2 boards, along with dozens of systems from Sega, Konami, and SNK. Emulation enthusiasts should probably be building statues of the man at this point.

The subscription funds a small team that helps with schematic acquisition, reverse engineering, and framework updates. This team approach is how they manage to push out updates for multiple systems simultaneously. Right now, one team member is working exclusively on Neo Geo Pocket save functionality, which will eventually carry over to other handheld cores.

The DE10-Nano question

The biggest unknown right now is platform compatibility. Jotego typically releases his work for both the MiSTer FPGA project and the Analogue Pocket via OpenFPGA. CPS3 is a demanding system that requires massive memory bandwidth to handle its fluid 2D animations and large character sprites.

The FPGA community has debated for years whether the MiSTer's DE10-Nano board has enough logic elements and memory speed to handle CPS3 accurately. The Analogue Pocket has its own constraints with its dual-FPGA setup. Jotego has mentioned testing next-generation FPGA development boards in recent interviews. We will have to wait and see if 3rd Strike fits on the current hardware or if it requires a hardware upgrade.

The core is still in its early stages. Until then, the fighting game community will just have to practice their parries on software emulators.