TurboGrafx-16 - CD Hardware Technical Specifications and Information

CD Hardware Technical Specifications and Information

• Oki MSM5205 ADPCM chip with variable speed input clock, and 64 KB DRAM for audio sample storage. Only one channel of 4-bit compressed audio (decompresses to 12-bit, top 10 bits output through DAC) was supported.
• Programmable, timer controlled, electronic volume attenuator to fade-out the CD-DA and ADPCM audio channels together or individually.
• The PC-Engine CD-ROM interface tray has 64 KB of DRAM for storage of program code and data loaded from the CD.
• The "System Card" contains the BIOS program used to boot CD media and provides functions for software to access CD hardware through a standardized interface. Later System Cards had extra RAM and updates to the BIOS.
• The Duo series has the same BIOS ROM (v3.00) and RAM (256 KB total) as a PC-Engine system equipped with a Super System Card. The Duo implements the memory as a single 256 KB SRAM chip rather than the split 64 KB DRAM / 192 KB SRAM.
• The list of known CD-ROM BIOS revisions are:
  • v1.00 - First release (HuCard, came with the PC-Engine CD-ROM interface unit)
  • v2.00 - Upgrade (HuCard, sold separately)
  • v2.10 - Upgrade (HuCard, sold separately) - bug fix?
  • v3.00 - Final release (built into several products and available as a HuCard - see below)
• The list of known System Card releases are:
  • System Card, v1.00 - First release. Came packaged with the original PC-Engine CD-ROM² System. Also available as a standalone purchase, in case the pack-in System Card was lost or damaged.
  • System Card, v2.00 – BIOS update. The only difference between this and the original System Card is the BIOS code update to v2.00. Otherwise, it is the same.
  • System, Card, v.2.10 – BIOS update. This may have been a bug fix for the System Card v2.00 BIOS code.
  • Super System Card - 1.5 Mbit RAM (192 KB) – RAM upgrade and BIOS update. This expands the RAM available for the CD-ROM unit to 256 KB when including the existing built in DRAM. It also offers a final BIOS update to v3.00. The PC-Engine Duo (Turbo Duo in North America) had 256 KB of RAM and the same v3.00 BIOS built into the system. Games developed for this System Card bore the title ‘Super CD’, and could not be played using an older System Card.
  • Arcade Card Pro - 17.5 Mbit RAM (2240 KB as 2 MB+192 KB) – RAM upgrade. This greatly expands the RAM available for the CD-ROM unit to 2240 KB. The BIOS revision was unchanged from v3.00. Games developed for this System Card bore the title ‘Arcade Card CD’, and could not be played using an older System Card. The Arcade Card Pro includes the extra 192 KB needed by the non Duo CD system. The 2 MB of RAM is accessed through ports or units of single 8 KB banks and is intended for graphics data storage rather than program code; its flexible addressing system allows for rapid transfer of data to VRAM.
  • Arcade Card Duo – 16 Mbit RAM (2048 KB) – RAM upgrade. This greatly expands the RAM available for the PC-Engine Duo system to 2048 KB. The BIOS revision was unchanged from v3.00. Games developed for this System Card bore the title ‘Arcade Card CD’, and could not be played using an older System Card. This will only work on the Duo systems, as it does not include the extra memory built into the Duo system.
  • Games Express Card – Bootleg system card. This was a bootleg System Card released by Games Express for play of unlicensed Games Express CD games. Only unlicensed Games Express games could be played on this System Card.