The CP System III (CPシステムIII, shīpī shisutemu surī) or CPS-3 is an arcade system board that was first used by Capcom in 1996 with the arcade game Red Earth. It was the second successor to the CP System arcade hardware, following the CP System II. It would be the last proprietary system board Capcom would produce before moving on to the Dreamcast-based Naomi platform.

History

The CP System III became the final arcade system board to be designed by Capcom. It features a security mechanism; games are supplied on a CD, which contains the encrypted game contents, and a security cartridge containing the game BIOS and the SH-2 CPU^[1] with integrated decryption logic, with the per-game key stored in battery-backed SRAM. Capcom chose the CD medium in order to keep down the price of the system.^[2] When the CP System III board is first powered on, the contents of the CD are loaded into a bank of Flash ROM SIMMs on the motherboard, where it is executed. The program code is then decrypted at run time via the security cartridge. The security cartridge is sensitive to any sort of tampering, which will result in the decryption key being erased and the cartridge being rendered useless. Games become unplayable when the battery inside the security cartridge dies. The lone exception is Street Fighter III: 2nd Impact, which uses a default set of decryption keys that are written to dead cartridges on boot,^[1] making it the few, if not the only CPS-3 game prevalent after support was dropped, due to its immunity to cartridge suicide.

In June 2007, the encryption method was reverse-engineered by Andreas Naive,^[3] making emulation possible.^[1] Later developments led to eventual bypassing of the suicide and security routines of the games, and the development of a so-called "super cartridge" capable of running all CPS-3 games.^[4]

Specifications

• Main CPU: Hitachi HD6417099 (SH-2) at 25 MHz
• RAM:
  • 512 KB Work RAM
  • 512 KB Sprite RAM
  • 8 MB Character RAM
  • 256 KB Color RAM
  • 32 KB SS RAM
• Storage:
  • SCSI CD-ROM drive
  • Flash ROM: Variable amount, up to 8 × 16 MB
• Sound chip: 16-channel 8-bit sample player, stereo
• Maximum color palette: 16 million shades^[5]
• Maximum number of colors on screen: 32,768^[6] (15-bit colour, 555 RGB)
  • Palette size: 131,072 pens
  • Colors per tile (backgrounds / sprites): 64 (6 bits per pixel) or 256 (8 bits per pixel), selectable
  • Colors per tile (text overlay): 16 (4 bits per pixel)
• Maximum number of objects: 1024, with hardware scaling^[6]
• Scroll faces: 4 regular + 1 text overlay 'score screen' layer
• Scroll features: Horizontal & vertical scrolling, linescroll, linezoom^[6]
• Framebuffer zooming
• Color blending effects
• Hardware RLE decompression of 6 bpp and 8 bpp graphics through DMA
• Resolution, pixels: 384×224 (standard mode) / 496×224 (widescreen mode)

List of games

All six games are developed by Capcom and are all head-to-head fighting games.