CP System III

The CP System III (CPシステムIII) or CPS-3 is an arcade system board that was first used by Capcom in 1997 with the arcade game Red Earth. It was the second successor to the CP System arcade hardware, following the CP System II.

History
The CP System III is the latest arcade system board 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 with integrated decryption logic, with the per-game key stored in battery-backed SRAM. When the CP System III board is first powered on, the contents of the CD are flashed onto a bank of 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 became unplayable when the battery inside the security cartridge died, which had to be replaced at cost to the owner. Furthermore, the CP System III was only capable of 2D graphics at a time when most games were being developed with 3D hardware in mind.

In June 2007, the encryption method was reverse-engineered by Andreas Naive, making emulation possible. The encryption turned out to be a fairly straightforward combination of rotates and XORs.

Specifications

 * Main CPU: Hitachi HD6417099 (SH-2) at 25 MHz
 * Storage:
 * SCSI CD-ROM drive
 * RAM (variable amount)
 * Flash ROM: 8 x 16 MiB
 * Sound chip: 16-channel 8-bit sample player, stereo
 * Maximum number of colors: 32768 (15 bit colour, 555 RGB)
 * Palette size: 131072 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
 * Scroll faces: 4 regular + 1 text overlay 'score screen' layer
 * Scroll features: Horizontal & vertical scrolling, linescroll, linezoom
 * 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)
 * Known games on this hardware: 6