General MIDI

For gaming, the game program is the instrument. The General MIDI data produced by the game is sent to expansion hardware in the computer (a sound card) and it is translated to audio. Alternatively, it is sent over a cable to external hardware (ie: Roland MT-32) to be translated to audio. External hardware might require an additional interface since the External hardware was probably designed for a sound studio filled with a wide variety of MIDI hardware and not just a personal computer. The Roland MT-32 for example requires an MPU-401 interface. There are external MPU-401 interface boxes. There are internal MPU-401 interface cards. There is also MPU-401 emulation software to replace the MPU-401 hardware. MPU-401 emulation does not significantly reduced quality.

Older MIDI hardware used pre-rendered synthesized instrument sounds. Most modern hardware uses PCM samples, which are a digital recordings of a single note played on a real instrument that is used to create every note in digital form.

Some regular sound cards translate GM directly and do not require external hardware. Software emulation can also do this. These two options will tend to produce 'electronic sounds' while external hardware tends to sound more like real instruments. Some specialized sound cards include MIDI specific hardware for music comparable to external hardware. Regular sound cards do not typically have MIDI ports but do typically have a 15-pin 'game port' (joystick port). An adapter cable is used to get MIDI-out and MIDI-in plugs and also a 15-pin pass-through for some cables (So players do not need to sacrifice joystick control for high quality music).

For modern systems, there are USB adapter cables to connect to external MIDI hardware using MIDI plugs. Standard cables of this type do not include an MPU-401 interface. There are cables that include a MPU-401 interface.

Pretty much any sound hardware with a MIDI-in port and GM compatibility will play GM audio simply by plugging a computer in to it (and having a game that produces GM output of course). A musical keyboard for example. Really, any digital instrument with MIDI-in. Music will sound like the device it is plugged into. Some instruments will require remapping channels to read the computer's GM data.