PC Engine CD

The PC-Engine was the first home video game console to offer a CD-ROM accessory, allowing the standard benefits of the CD medium: more storage, cheaper media costs, and red book audio. The efficient design, backing of many of Japan's major software producers, and the additional CD ROM capabilities gave the PC Engine a very wide variety of software, with several hundred games for the CD formats

[collapse collapsed title=read more...]

The various CD-ROM game types are:

CD-ROM (pronounced CD-ROM-ROM) : Standard CD-ROM game.

Super CD-ROM : Requires a compatible system or upgrade card.

Arcade CD-ROM : Requires an upgrade card.

The PC-Engine CD-ROM peripheral had no built in RAM for storage of program code and data loaded from the CD. With the exception of the Duo hardware series, all RAM for the PC-Engine CD-ROM was contained on a ‘System Card’. A System Card was a HuCard, which contained not only RAM, but also BIOS software for the PC-Engine CD-ROM unit

While the standard CD-ROM and Super CD-ROM had RAM for data storage which was accessed directly, the Arcade CD-ROM cards accessed the RAM in a slightly different way.

Both the Pro and Duo versions of the Arcade Card worked in the same way. Just as with the Super CD-ROM, up to 256KB of the RAM was able to be accessed directly by the CPU. The other 2048KB was accessed indirectly by transferring data to the other 256KB of RAM on the fly. This was done rather seamlessly, so that even though the CPU could only use up to 256KB of RAM at once, data could be swapped to and from the other 2048KB of RAM at any time.

This technique of swapping data from RAM to RAM was much faster than loading the data directly from the CD into RAM, and offered developers a significant advantage over the previous System Card formats, as is evidenced by the many conversions of well-animated Neo Geo fighting games to the Arcade CD-ROM.

One technique that was used by games pre-dating the Arcade Card upgrade was to store graphics data in the 64K audio RAM (used for ADPCM samples) that was present. This RAM could be directly populated by the CD-ROM hardware (it had a direct DMA channel from the CD controller) without CPU intervention, and the memory could be accessed in an indirect fashion, similar to the Arcade Card, allowing data stored in it to appear as a 64K stream of linear data that could be easily transferred to the system RAM.

NEC developed a prototype adaptor that connected a PC through the HuCard slot, allowing the PC to control the PC Engine's CD ROM as it would any normal SCSI drive. Due to falling CD drive prices and the increasing undesirability of a single-speed SCSI drive, it was never released. It was however previewed in NEC's official US TurboDuo magazine.

The PC Engine-CD was ultimately succeeded by the PC Engine Duo, which integrated the CD drive and the main unit into one console.

[/collapse]