Game control adapter
Originally called the Analog-to-digital port (A-to-D port), the game port, joystick port, or game control adapter is a 15-pin connector port first found on IBM computers in 1981. The game port is handled by the SIO (super input/output) and allows users to connect such devices as joysticks, gamepads, steering wheels, and other devices that allow additional functionality to the computer.
The picture shows the back of a computer sound card. In this picture, the joystick port is the 15-pin yellow connection at the bottom of the card.
Some motherboards included an internal ISA (Industry Standard Architecture) or PCI (peripheral component interconnect) card. If a motherboard did not have this feature, a joystick port could be installed.
Today, this port has been replaced by USB (universal serial bus), and the 15-pin connector is no longer used.