Sega TeraDrive

Last updated
Developer Sega
Manufacturer IBM
Type Video game console  / Personal computer
Generation Fourth generation
Release date
  • JP: May 31, 1991
[1] [2]
Media Cartridge, diskette
CPU 16-bit Intel 80286
Motorola 68000
Zilog Z80
Mega Drive
Successor Amstrad Mega PC (3rd party product developed on licence by Amstrad)

The TeraDrive(テラドライブ,TeraDoraibu) is an IBM PC compatible system with an integrated Mega Drive, developed by Sega and manufactured by IBM in 1991. 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.

IBM PC compatible computers are computers similar to the original IBM PC, XT, and AT, able to use the same software and expansion cards. Such computers used to be referred to as PC clones, or IBM clones. They duplicate almost exactly all the significant features of the PC architecture, facilitated by IBM's choice of commodity hardware components and various manufacturers' ability to reverse engineer the BIOS firmware using a "clean room design" technique. Columbia Data Products built the first clone of the IBM personal computer by a clean room implementation of its BIOS.

Sega Japanese video game developer and publisher and subsidiary of Sega Sammy Holdings

Sega Games Co., Ltd. is a Japanese multinational video game developer and publisher headquartered in Tokyo, Japan. The company, previously known as Sega Enterprises Ltd. and Sega Corporation, is a subsidiary of Sega Holdings Co., Ltd., which is part of Sega Sammy Holdings. Its international branches, Sega of America and Sega of Europe, are respectively headquartered in Irvine, California and London. Sega's arcade division, once part of Sega Corporation, has existed as Sega Interactive Co., Ltd., also a Sega Holdings subsidiary, since 2015.


The system was only released in Japan, as Sega hoped that integrating the then popular Mega Drive console into an IBM PC would attract potential customers wishing to purchase a PC. The system proved unpopular and failed.

Japan Constitutional monarchy in East Asia

Japan is an island country in East Asia. Located in the Pacific Ocean, it lies off the eastern coast of the Asian continent and stretches from the Sea of Okhotsk in the north to the East China Sea and the Philippine Sea in the south.


One of the main processors used for the system is the Intel 80286, which was released in 1982. However, by the time when the TeraDrive was released in 1991, this processor was almost 10 years out of date - the more powerful 25 MHz Intel 80486 had been released in 1989, 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, that ran at 7.67 MHz and 3.58 MHz respectively. [3]

Intel 80286

The Intel 80286 is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086 based CPU with separate, non-multiplexed address and data buses and also the first with memory management and wide protection abilities. The 80286 used approximately 134,000 transistors in its original nMOS (HMOS) incarnation and, just like the contemporary 80186, it could correctly execute most software written for the earlier Intel 8086 and 8088 processors.

Intel 80486 higher performance follow-up to the Intel 80386 microprocessor introduced in 1989

The Intel 80486, also known as the i486 or 486, is a higher performance follow-up to the Intel 80386 microprocessor. The 80486 was introduced in 1989 and was the first tightly pipelined x86 design as well as the first x86 chip to use more than a million transistors, due to a large on-chip cache and an integrated floating-point unit. It represents a fourth generation of binary compatible CPUs since the original 8086 of 1978.

Motorola 68000 microprocessor

The Motorola 68000 is a 16/32-bit CISC microprocessor, which implements a 32-bit instruction set, with 32-bit registers and 32-bit internal data bus, but with a 16-bit data ALU and two 16-bit arithmetic ALUs and a 16-bit external data bus, designed and marketed by Motorola Semiconductor Products Sector. Introduced in 1979 with HMOS technology as the first member of the successful 32-bit Motorola 68000 series, it is generally software forward-compatible with the rest of the line despite being limited to a 16-bit wide external bus. After 39 years in production, the 68000 architecture is still in use.

The machine's front panel ports included two 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.

Serial port communication interface socket/plug

In computing, a serial port is a serial communication interface through which information transfers in or out one bit at a time. Throughout most of the history of personal computers, data was transferred through serial ports to devices such as modems, terminals, and various peripherals.

PS/2 port 6-pin mini-DIN connector used for connecting some keyboards and mice to a PC compatible computer system

The PS/2 port is a 6-pin mini-DIN connector used for connecting keyboards and mice to a PC compatible computer system. Its name comes from the IBM Personal System/2 series of personal computers, with which it was introduced in 1987. The PS/2 mouse connector generally replaced the older DE-9 RS-232 "serial mouse" connector, while the PS/2 keyboard connector replaced the larger 5-pin/180° DIN connector used in the IBM PC/AT design. The PS/2 keyboard port is electrically and logically identical to the IBM AT keyboard port, differing only in the type of electrical connector used. The PS/2 platform introduced a second port with the same design as the keyboard port for use to connect a mouse; thus the PS/2-style keyboard and mouse interfaces are electrically similar and employ the same communication protocol. However, unlike the otherwise similar Apple Desktop Bus connector used by Apple, a given system's keyboard and mouse port may not be interchangeable since the two devices use different sets of commands and the device drivers generally are hard-coded to communicate with each device at the address of the port that is conventionally assigned to that device.

Parallel port an interface for connecting peripherals to computers

A parallel port is a type of interface found on computers for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once, in parallel communication, as opposed to serial interfaces that send bits one at a time. To do this, parallel ports require multiple data lines in their cables and port connectors, and tend to be larger than contemporary serial ports which only require one data line.

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

Motherboard printed circuit board (PCB) found in all modern computers

A motherboard is the main printed circuit board (PCB) found in general purpose computers and other expandable systems. It holds and allows communication between many of the crucial electronic components of a system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals. Unlike a backplane, a motherboard usually contains significant sub-systems such as the central processor, the chipset's input/output and memory controllers, interface connectors, and other components integrated for general purpose use and applications.

Industry Standard Architecture 16-bit internal bus of IBM PC/AT

Industry Standard Architecture (ISA) is the 16-bit internal bus of IBM PC/AT and similar computers based on the Intel 80286 and its immediate successors during the 1980s. The bus was (largely) backward compatible with the 8-bit bus of the 8088-based IBM PC, including the IBM PC/XT as well as IBM PC compatibles.


Its interface consisted of a start-up menu with several options, including a file manager, DOS, a clock and Mega Drive mode. [4]

A file manager or file browser is a computer program that provides a user interface to manage files and folders. The most common operations performed on files or groups of files include creating, opening, renaming, moving or copying, deleting and searching for files, as well as modifying file attributes, properties and file permissions. Folders and files may be displayed in a hierarchical tree based on their directory structure. Some file managers contain features inspired by web browsers, including forward and back navigational buttons.

DOS group of closely-related PC-compatible operating systems

DOS is a family of disk operating systems, hence the name. DOS primarily consists of MS-DOS and a rebranded version under the name IBM PC DOS, both of which were introduced in 1981. Other later compatible systems from other manufacturers include DR-DOS (1988), ROM-DOS (1989), PTS-DOS (1993), and FreeDOS (1998). MS-DOS dominated the x86-based IBM PC compatible market between 1981 and 1995.

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. 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. [3]

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. [3]


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.

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. [3]


Three models were available, ranging from ¥148,000 (USD $1100/GBP £580) to ¥248,000 (USD $1840/GBP £950).

Technical specifications [3]
ModelModel 1Model 2Model 3
Price (at launch)¥148,000¥188,000¥248,000
Processor AMD 80286 (10 MHz), Motorola 68000, Zilog Z80
RAM (available / maximum)640 KB/2.5 MB1 MB/2.5 MB2.5 MB/2.5 MB
Storage 1 FDD 2 FDDs1 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)
I/O ports
Operating system IBM DOS J4.0/V


The system proved unpopular with the Japanese market and ultimately failed. 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. [3]

A new PC was also in the discussion stages to be developed by Sega under the leadership of ex-IBM executive Narutomi. [5] but this likely never got past the discussion stages due to the failure of the TeraDrive.

Similar products

A similar, but unrelated system was manufactured by Amstrad and sold under the name Mega PC in PAL areas such as Europe and Australia. 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.

See also

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  1. "OLD-COMPUTERS.COM Museum ~ Sega Teradrive" . Retrieved 2006-11-22.
  2. "Original page". Archived from the original on June 17, 2006. Retrieved 2007-07-22.CS1 maint: BOT: original-url status unknown (link)
  3. 1 2 3 4 5 6 "Sega / IBM TeraDrive" . Retrieved 2006-11-22.
  5. Ex-IBM man joins Sega to push game machines, 19 August 1991