MEGA DRIVE SOUND DRIVERS
Same notes. Six sound drivers.
A Mega Drive game did not play its own music: a small program, its sound driver, wrote to the FM and PSG chips a fixed number of times a second and streamed the drums through an 8-bit DAC. Each driver below was measured in a real game. Pick one and hear what its timing does to the same song, played by the cycle-accurate chip.
Write your own
Switch drivers while it plays. Keys 1 to 6 pick one, space plays.
Pick a driver
How often it writes, how fast its drums stream, and the game it was measured in.
measured in Streets of Rage 2
Pick a song
Three loops written for this page, each with its harmony checked.
What changes
The tick
The driver wakes a fixed number of times a second and writes everything that is due. At 60 Hz, once a video frame, every note, vibrato step and fade lands on that grid. A timer at a few hundred hertz is close to free timing: smoother vibrato, tighter grace notes.
The drum rate
Drums were 8-bit samples the driver pushed into the DAC one byte at a time. A fast stream keeps the snare's top; a slow one gives the grainy thump of many early games.
One drum at a time
Many drivers played a single sample: a new hit cut the last one off. Mixed lets them ring together, as chipvoice does by default.