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 that are able to use the same software and expansion cards. Such computers were referred to as PC clones, or IBM clones. The term "IBM PC compatible" is now a historical description only, since IBM has ended its personal computer sales. The industry jargon "PC" sometimes doesn't mean "personal computer" generally, but rather a Windows computer, in contrast to a Mac.

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 Shinagawa, Tokyo. Its international branches, Sega of America and Sega 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. since 2015. Both companies are subsidiaries of Sega Holdings Co., Ltd., which is in turn a part of Sega Sammy Holdings. From 1983 until 2001, Sega also developed and sold video game consoles.


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 Island country 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 However, by the time when the TeraDrive was released in 1991, this processor was almost 10 years out of date - the more powerful 25 MHz Intel 80486 had been released in 1989, making the TeraDrive's central processor 2 generations behind its time.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 microprocessor model

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 family of 32-bit microprocessors introduced in 1989, including DX, SX and SL models

The Intel 80486, also known as the i486 or 486, is the successor model of 32-bit x86 microprocessor to the Intel 80386. Introduced in 1989, the 80486 improved on the performance of the 80386DX thanks to on-die L1 cache and floating-point unit, as well as an improved, five-stage tightly-coupled pipelined design. It was the first x86 chip to use more than a million transistors. It represents the 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, introduced in 1979 by Motorola Semiconductor Products Sector.

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 87-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 main printed circuit board (PCB) for a computing device

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 platform-independent acronym for Disk Operating System, which was initially introduced by IBM for the System/360 mainframe and later became common shorthand for the popular family of disk-based operating systems for x86-based IBM PC compatibles. DOS primarily consists of Microsoft's MS-DOS and a rebranded IBM version under the name PC DOS, both of which were introduced in 1981. Later compatible systems from other manufacturers are DR DOS, ROM-DOS, PTS-DOS, Embedded DOS, FreeDOS (1998), and RxDOS. MS-DOS dominated the 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