TurboGrafx-16 - Variations - Peripheral Compatibility

Peripheral Compatibility

All PC Engine systems support the same controller peripherals, including pads, joysticks and multitaps. Except for the Vistar, Shuttle, GT, and systems with built-in CD-ROM drives, all PC Engine units shared the same expansion connector, which allowed for the use of devices such as the CD-ROM unit, game saves and AV output.

The TurboGrafx and Vistar units use a different controller port than the PC Engines, but adaptors are available and the protocol is the same. The TurboGrafx offers the same expansion connector pinout as the PC Engine, but has a slightly different shape so peripherals must be modified to fit.

The Super System Card provides 192 kB of RAM, supplementing the built in 64K of DRAM found in the CD interface tray. The PC-Engine Duo/R/RX consoles have the Super System Card’s 192 KB of RAM plus the 64K of standard RAM and v3.00 BIOS software built in, and can play both CD-ROM² and Super CD-ROM² games without using any additional cards.

The Arcade Card Pro is designed for the original PC-Engine CD-ROM² and Super CD-ROM² peripherals, adding the 2304 KB of RAM required by Arcade CD-ROM² games. It could, of course, also play standard CD-ROM² and Super CD-ROM² games.

The Arcade Card Duo is for the PC-Engine Duo/R/RX consoles and adds 2048 KB RAM. Because the PC-Engine Duo series of systems have 256K of RAM built-in, this does not need to be provided and is why the Arcade Card Duo contained less RAM and was less expensive than the Pro version.

Note: Because the aforementioned consoles use the same BIOS revision as the Arcade Card Pro, it is not known (as a cost-saving measure) if the Arcade Card Duo includes the BIOS software itself, or if the existing built-in BIOS is used.

The various CD-ROM game types are:

  • CD-ROM² : Standard CD-ROM game.
  • Super CD-ROM² : Requires a compatible system or upgrade card.
  • Arcade CD-ROM² : Requires an upgrade card.

While the standard CD-ROM² and Super CD-ROM² had RAM for data storage which was accessed directly, the Arcade CD-ROM² 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-ROM², up to 256 KB of the RAM was able to be accessed directly by the CPU. The other 2048 KB was accessed indirectly by four indirect self incrementing/decrementing address registers. These registers were mapped into memory hardware bank and also mapped into 4 special memory banks. Reading and writing sequential data was speed up and reduced cycle cost due to these new registers. This meant *far* data could be accessed with these four registers without having to map banks of memory into the CPU's logical address range, and could be transferred to VRAM ports faster and easier, as is evidenced by the many conversions of well-animated Neo Geo fighting games to the Arcade CD-ROM². The Arcade card was known to have existed in working prototype form as early as mid '92 from looking at (non public) source code files to Art of Fighting ACD port.

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 but at a much-much slower interface, allowing data stored in it to appear as a 64 KB stream of linear data that could be easily transferred to the system RAM.

NEC also manufactured a very large line of personal computers, one of which featured a single-speed CD ROM drive identical to the PC Engine version. They were designed to be interchangeable, which is why the PC Engine's IFU-30 CD ROM interface could be purchased without a CD ROM drive.

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 Pioneer LaserActive was a laserdisc player with an expansion bay. One of the expansion modules released allowed it to play PC Engine titles (HuCards, CD-ROM2 and Super CD) as well as games released on laserdisc (LD-ROM2) that only worked on this setup. Eleven LD-ROM2 titles were released in Japan, though only three of them were released in North America.

Read more about this topic:  TurboGrafx-16, Variations

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