Game port

The game port is a device port that was found on IBM PC compatible and other computer systems throughout the 1980s and 1990s. It was the traditional connector for joystick input, and occasionally MIDI devices, until made obsolete by USB in the late 1990s.

Originally located on a dedicated Game Control Adapter expansion card, the game port was later integrated with PC sound cards, and still later on the PC's motherboard. During the transition to USB, many input devices used the game port and a USB adapter dongle was included for systems without a game port.

At the time IBM was developing its game port, there was no industry standard for controller ports, although the Atari joystick port was close. It was introduced in 1977 with the Atari Video Computer System, and was later used on the VIC-20 (1980), Commodore 64 (1982), and Amstrad's PC1512 (1986).

In contrast with the IBM design, the Atari port was primarily designed for digital inputs (including a pair of two-axis/four-contact digital joysticks, each with a single pushbutton trigger). Its only analog connections were intended for paddles -- although, as there were two analog inputs per port, each port could theoretically support a two-axis analog joystick, touchpad, trackball, or mouse (some of these being eventually developed for Atari systems).

The Apple II, BBC Micro, TRS-80 Color Computer, and other popular 8-bit machines all used different, incompatible, joysticks and ports. In most respects, the IBM design was similar to, or more advanced than, existing designs.

The IBM PC game port first appeared during the initial launch of the original IBM PC in 1981, in the form of an optional US$55 expansion card known as the Game Control Adapter. The design allowed for four analog axes and four buttons on one port, allowing two joysticks or four paddles to be connected via a special "Y-splitter" cable.

Originally available only as add-on that took up an entire slot, game ports remained relatively rare in the early days of the IBM PC, and most games used the keyboard as an input. IBM did not release a joystick of its own for the PC, which did not help. The most common device available was the Kraft joystick, originally developed for the Apple II but easily adapted to the IBM with the addition of a third button on the back of the case. When IBM finally did release a joystick, for the IBM PCjr, it was a version of the Kraft stick. However, it connected to the computer using two incompatible 7-pin connectors, which were mechanically connected together as part of a larger multi-pin connector on the back of the machine. This eliminated the need for the Y-adapter. Adapters for Atari-style "digital" sticks were also common during this era.

The game port became somewhat more common in the mid-1980s, as improving electronic density began to produce expansion cards with ever-increasing functionality. By 1983, it was common to see cards combining memory, game ports, serial and parallel ports and a realtime clock on a single expansion card. The era of combo expansion cards largely came to an end by the late 1980s, as many of the separate functions normally provided on plug-in boards became common features of the motherboard itself. Game ports were not always part of this supported set of ports.