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From Sonic Retro

Sega Teradrive

One variation of the Sega Mega Drive deserves special mention, and that is the Sega TeraDrive. The TeraDrive is a hybrid between a Sega MegaDrive, and a full-featured IBM 286 computer, released to the Japanese market in early 1991. The Teradrive was a fully integrated system, with both the MegaDrive and PC components existing together on one motherboard. This sets the TeraDrive apart from the only other known PC/MegaDrive hybrid system, the 386 Amstrad MegaPC, which used an expansion ISA card to add MegaDrive functionality.

Unlike with the Amstrad MegaPC, the TeraDrive also allows some degree of interaction between the PC hardware and the MegaDrive hardware. The only known software to make use of this is a game called "Puzzle Contruction", which was included with the TeraDrive. This program features an editor which allowed a user to design and run puzzles from the PC. The game appears to make use of the Mega Drive components for sound, and may also make use of the VDP, but more likely it uses x86 code. Exactly how the x86 code communicates with the MegaDrive hardware, and the limits of what is possible through this interface, are currently unknown.

It is rumoured that the Teradrive shipped with a software development kit (SDK) for developing MegaDrive games, although this claim is currently unsupported. No known development software for the Teradrive exists. This rumour may have originated from misunderstanding or exaggeration of the features provided by the bundled "Puzzle Contruction" software.

The Teradrive includes an expansion connector on the top of the unit, which provides the same functionality as the expansion connector on the MegaDrive. Although no Mega CD unit was ever released for the Teradrive, at least two prototype units were developed. Reportedly, Sega of Japan planned to release the MegaCD expansion for the Teradrive based on the top-loading design of the MegaCD II, but poor sales of the Teradrive caused the development to be cancelled before designs left the prototype stage, and Sega instead focused on the development of the Sega Saturn.

In late 1993, the concept of a hybrid PC/MegaDrive found its way outside of Japan in the form of the Amstrad MegaPC, although it was based on an entirely different design. The unit wasn't very successful regardless of market, and this was largely due to its high price (about US$3000). Reportedly, a souped-up version called the MegaPlus was later offered based on a 486DX-33 CPU machine with 4 MB of RAM, but very few seem to have made it out the door. The TeraDrive and its successor have all but disappeared with the passage of time.

TeraDrive Models

The TeraDrive came in 3 different models with the main differences being RAM, Storage, and Price.

Model 1

• Processors: 10MHz Intel 80286, 7.61MHz (PAL) or 7.67MHz (NTSC) Motorola 68000, and 3.55MHz (PAL) or 3.58MHz (NTSC) Zilog Z80
• RAM Avail.: 640KB
• RAM Max.: 2.5MB
• Storage: 1 - Floppy Drive
• Graphics Modes:
  • PC Mode
    • 640x480 (262144 colors/16 onscreen)
    • 320x200 (262144 colors/256 onscreen)
  • Mega Drive Mode
    • 320x224 (512 colors/64 onscreen)
• I/O Ports
  • PC
    • 1 - VGA
    • 1 - Parallel
    • 2 - Serial
    • 2 - PS/2
  • Mega Drive
    • 2 - Mega Drive Controller Ports
    • 1 - Expansion (This would be used to attatch the MEGA CD.)
• Operating System: IBM DOS J4.0/V
• Price ¥148,000 ($1100, €790)

Model 2

• Processors: 10MHz Intel 80286, 7.61MHz (PAL) or 7.67MHz (NTSC) Motorola 68000, and 3.55MHz (PAL) or 3.58MHz (NTSC) Zilog Z80
• RAM Avail.: 1MB
• RAM Max.: 2.5MB
• Storage: 2 - Floppy Drive
• Graphics Modes:
  • PC Mode
    • 640x480 (262144 colors/16 onscreen)
    • 320x200 (262144 colors/256 onscreen)
  • Mega Drive Mode
    • 320x224 (512 colors/64 onscreen)
• I/O Ports
  • PC
    • 1 - VGA
    • 1 - Parallel
    • 2 - Serial
    • 2 - PS/2
  • Mega Drive
    • 2 - Mega Drive Controller Ports
    • 1 - Expansion (This would be used to attatch the MEGA CD.)
• Operating System: IBM DOS J4.0/V
• Price ¥188,000 ($1400, €1020)

Model 3

• Processors: 10MHz Intel 80286, 7.61MHz (PAL) or 7.67MHz (NTSC) Motorola 68000, and 3.55MHz (PAL) or 3.58MHz (NTSC) Zilog Z80
• RAM Avail.: 2.5MB
• RAM Max.: 2.5MB
• Storage: 1 - Floppy Drive, 1 - 30MB Hard Drive
• Graphics Modes:
  • PC Mode
    • 640x480 (262144 colors/16 onscreen)
    • 320x200 (262144 colors/256 onscreen)
  • Mega Drive Mode
    • 320x224 (512 colors/64 onscreen)
• I/O Ports
  • PC
    • 1 - VGA
    • 1 - Parallel
    • 2 - Serial
    • 2 - PS/2
  • Mega Drive
    • 2 - Mega Drive Controller Ports
    • 1 - Expansion (This would be used to attatch the MEGA CD.)
• Operating System: IBM DOS J4.0/V
• Price ¥248,000 ($1840, €1400)