SonicHurricane.com wrote up a nifty article explaining the mechanics used when a turbo speed setting is applied to a Street Fighter game.Starting with Hyper Fighting and Super Turbo, most Capcom fighting games have supported accelerated game speed settings. Since all Capcom titles already display 60 frames per second on the screen and sample controller inputs at a refresh rate of 60 frames per second, turbo speeds are implemented by skipping over frames. Increasing the frame rate would be impossible because most televisions wouldn’t support it.
Taking Capcom Fighting Evolution as an example, every frame is drawn and shown on the screen at the lowest game speed setting. Every 60 internal frames, the overhead match clock counts down one second.
Increasing the speed setting does not increase the number of frames shown per second, but rather causes internal frames to skip at regular intervals. At speed two, 1 frame skips for every 6 frames shown. At speed three, which is the default speed, 1 frame skips for every 4 frames shown. 1 frame skips for every 3 frames shown at speed four and 1 frame skips for every 2 frames shown at the maximum speed of five.
