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Sega TeraDrive
Manufacturer IBM (for Sega)
Type Video game console / Personal computer
Generation Fourth generation
Retail availability Japan May 31, 1991[1][2]
Media Cartridge, Diskette
CPU 16-bit Intel 80286
Mega Drive/Genesis
Successor Amstrad Mega PC (3rd party product developed on licence by Amstrad)

The TeraDrive was a 16-bit PC with an integrated Mega Drive, manufactured by IBM for Sega. The system was only released in Japan, as Sega was hopeful that by integrating its then popular Mega Drive console into an IBM PC would be an attraction for potential customers wishing to purchase a PC. The system however proved unpopular with the Japanese market and ultimately failed. A new PC was also in the discussion stages to be developed by Sega under the leadership of ex-IBM executive Narutomi[3], but this likely never got past the discussion stages due to the failure of the TeraDrive.

The TeraDrive allowed for Mega Drive games to be played the same time as the PC section is being used, as it is possible for the Mega Drive and PC hardware to interact with each other. Its interface consisted of a start-up menu with several options, including a file manager, DOS, a clock and Mega Drive mode.[4] There is very little English information known about the TeraDrive or about software development on the platform, with any known information relatively scarce.

Production numbers are unknown. The system is moderately rare in Japan, although prices are rising rapidly due to collector demand. The price to buy a TeraDrive in June 2003 was triple the price it was 2 years prior.[5]


Software Development Kit

The machine included IBM drivers bundled on a floppy disk, which enabled properly written software to operate in the machine's RAM and then run on the native Mega Drive hardware. It shipped with a software development kit (SDK) which made it possible to develop your own Mega Drive games. A good example of this shown in the Puzzle Construction program, one of the very few software titles included with the TeraDrive, which included a PC-side editor suite for changing the features of a falling-block puzzle game, then playable on the Mega Drive side. The operating system shipped with the system was IBM's DOS J4.0/V, which was similar to PC DOS.[5]

There was often speculation that the TeraDrive was specifically designed as a purpose-made Software Development Kit, to allow software makers to develop their software titles for the Mega Drive. However, given the release date of the TeraDrive (some years after the initial Mega Drive release), as well as the availability of Sega's own game development hardware, it is unlikely the TeraDrive was designed for this purpose.[5]


The system's peripherals which were included or available separately, included 2 × Mega Drive pads, 1 × PS/2 Mouse, 1 × Sega branded PS/2 IBM keyboard and 1 × 3-button joystick. The Mouse and Mega Drive pads were practically identical to those found on the Mega Drive console version.

Technical specifications

Specifications[5] Model 1 Model 2 Model 3
Price (at launch) ¥148,000
Processor AMD 80286 (10 MHz), Motorola 68000, Zilog Z80
RAM (available/max) 640 KB/2.5 MB 1 MB/2.5 MB 2.5 MB/2.5 MB
Storage 1 FDD 2 FDDs 1 FDD, 1 30MB HDD
Graphics Modes
  • PC Mode
    • 640×480 pixels (262144 colors / 16 onscreen)
    • 320×200 pixels (262144 / 256; Mode 13h)
  • Mega Drive Mode
    • 320×224 pixels (512 / 64)
Input / Output Ports
Operating System IBM DOS J4.0/V
Foreign prices are converted estimates during the time of sale
(given that the TeraDrive was only released in Japan)

Three models were available, ranging from ¥148,000 (USD $1100/GBP £580) to ¥248,000 (USD $1840/GBP £950). A monitor which was manufactured by a 3rd party company but with Sega branding, was available separately at a price of ¥79,800 (estimated USD $600/GBP £300 at the time), which was capable of displaying 15 kHz RGB video signals from the Mega Drive hardware and a 31 kHz VGA output from the PC hardware, both from the VGA connector.[5] The system's typical power consumption is in the region of 27 W.


One of the main processors used for the system is the Intel 80286, which was released in 1982. However, at the time when the TeraDrive was released in 1991, this processor was almost 10 years out of date, with the more powerful 25 MHz Intel 80486 having already been released 2 years prior in 1989, thus making the TeraDrive's central processor 2 generations behind its time. The system also contains a Motorola 68000 and a Zilog Z80, the same processors which were used in the Mega Drive. The 68000 runs at 7.61 MHz and 7.67 MHz and the Z80 runs at 3.55 MHz and 3.58 MHz in PAL and NTSC consoles respectively.[5]

Input/Output Ports

The machine's front panel ports included 2 × Mega Drive pad ports which were similar in design to 9-pin male serial ports, and 2 PS/2 ports to the right side of the unit to accommodate for the mouse and keyboard.

The system also contained several ports to its rear. In order from left to right: 9-pin male serial port, 25-pin parallel port for connection to a printer, stereo RCA jacks and composite NTSC video output for connection to a TV, analogue RGB for monitor connection, and a 2nd 9-pin male serial connector labelled "EXT", similar to that found on the rear of an original Mega Drive base unit.

The motherboard also had a spare ISA slot available for expansion, with a hole at the rear of the unit to accommodate this.

Amstrad Mega PC

A similar, but unrelated system was manufactured by Amstrad and sold under the name Mega PC in PAL areas such as Europe and Australia. Its success was very short-lived due to its high retail price of £599 (about $1200). Given that it lacked several key features which the TeraDrive boasted, it made its price tag unattractive to consumers, even though both products were marketed in different countries. Although it boasted a higher specification than that of Sega's TeraDrive, it was unable to act as a Software Development Kit due to the inability to interact both the PC and the Mega Drive together, as it was essentially just a PC with a Mega Drive bundled inside.


  • In the Dreamcast game Segagaga, the supercomputer that runs all functions of Sega in the year 2025 is called the TeraDrive.[6]

See also

External links


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