Undoubtedly, one of my favorite creations in the world of music is that of MIDI. You're probably familiar with MIDI files (.mid), songs which tend to not sound too great (although I have a soft spot for them). But in actually, MIDI itself is a language, a way for devices to communicate and send messages. For instance, a musical keyboard that's controlling a synthesizer uses MIDI commands to control its sounds. These simple on/off changes have revolutionized how we interface electronic musical hardware. But really, I do want to talk about MIDI files, or more specifically MIDI standards.
In 1987, Roland released the MT-32, the Multi-Timbre Sound Module. Containing 128 different instruments and a drum kit, the MT-32 was a powerful device which began a line of colorful MIDI specifications. Four years later, General MIDI (GM) was brought to the world by the MIDI Manufacturers Association, and the standard was set for MIDI-based computer sound cards. In that same year, Roland released General Standard (GS), a specification which has prevailed 20 years later. If your sound card supports MIDI (99.9% chance it does), it probably has GS on it. Roland also used GS in their Sound Canvas line of tone generators, but the instruments sounded much better than those featured on most sound cards.
But Yamaha wouldn't settle for simply GS, so in 1994, they created XG. Which further improved the number of instruments presented by GS. XG has been extremely prominent among Japanese video game music arrangers. Finally, General MIDI Level 2 was created in 1999, the last specification thus far.
Indeed, there are quite a few different standards! But aside from MIDI files, how are they really used? The answer to that is through tone generators, such as the MT-32 and Sound Canvas series which I mentioned above. These synthesizers provide composers with a plethora of sounds which they can use to create or supplement their composing. Effects are commonly present on these small, musical boxes, such as reverb, chorus, and delay. But I mentioned you have a MIDI-based synthesizer on your sound card already. So why get one of these? Well, aside from sounding leagues better, tone generators also allow you to modify the sounds themselves. Most through ASDR (attack/sustain/decay/release) envelopes, which allow you to change how aggressive the sound is, how long it takes to fade out, and so forth. Others are more advanced, allowing you to make direct changes to how the sound is synthesized.
There are a plethora of different tone generators out there, many of which have been used in video games. Falcom used a Roland SC-88 in their intense action RPG Ys I & II Eternal. If you're familiar with ZUN's Touhou series, the music is made using a Roland SD-90, which is based on GS. Undoubtedly my favorite tone generator, however, is the Yamaha MU-1000/2000 (they're essentially identical). This particular box has an XG-based synthesizer on board, and sounds pretty good by itself. However, what really improves its capabilities are its built in amplifiers, which provide an incredibly rockin' distortion. I heavily encourage you to check out the artists S.S.H. and Ezel-Ash. Both use a MU-1000/2000 and produce absolutely awesome music.
Although these tone generators produce some really awesome sounds, they're slowly being phased out in favor of VSTs, due to costs and efficiency. However, some keyboards/workstations are still in production, such as the Roland Fantom-X series, which has been used by many professional musicians such as Dream Theater's Jordan Rudess.
There truly is so much more to the world of MIDI than the .mid files you find over at VGMusic (which are awesome, too). Hopefully I've sparked some kind of interest in you!