Every CPS2 board contained a small, encrypted program and a lithium battery soldered directly to the board. This battery powered a small section of RAM that held the decryption key for the game’s code. If that battery died (which they all do, typically after 5-10 years), the decryption key vanished. The board would "commit suicide"—bricking itself into an unplayable state.
In the world of arcade emulation, few acronyms carry as much weight—or cause as much confusion—as CPS2. For fans of 1990s fighting games, scrolling beat ‘em ups, and pixel-perfect shooters, the CPS2 (Capcom Play System 2) represents a golden era. To play these games in MAME (the Multiple Arcade Machine Emulator), you need more than just the game ROMs; you need a digital skeleton key known as the MAME CPS2 BIOS . mame cps2 bios
This was a nightmare for collectors and a massive barrier for preservationists. For years, emulating CPS2 games in MAME was difficult because the ROMs were dumped in their encrypted, "battery-alive" state. MAME had to emulate the encryption chip and the battery, which was complex and imperfect. Every CPS2 board contained a small, encrypted program