When I started with MIDI in the mid-late 80's (on a DOS computer), my first MIDI Interface was a PC card that fit into an ISA slot and cost $170.
When soundcards later appeared, you could get a MIDI cable that attached to the 15-pin joystick/game port.
Now there are very inexpensive MIDI to USB converters and cables, as well as full-fledged external USB or FireWire interfaces that provide full sound mixing, recording, playback and MIDI interface for $100 and up.
Although MIDI stands for Musical Instrument Digital Interface, back then we called it Money Intensive Digital Insanity.
Steve