Turbo button refers to a button on a piece of electronic equipment, which makes the equipment run faster (or slower) in some way. Its two most popular incarnations are:
- On personal computers, the Turbo button changes the effective speed of the system. It usually accomplishes this by either adjusting the CPU clock speed directly, or by turning off the processor's cache, forcing it to wait on slow main memory every time. The button was generally present on older systems, and was designed to allow the user to play older games that depended on processor speed for their timing. Systems could also use the keyboard combination of ctrl-alt-+/-, '-' switching turbo OFF and '+' switching it ON (ctrl-alt-\ to toggle between turbo/normal mode on ITT Xtra machines). Of course, calling it a "turbo" button when its function slows the system down can be a bit misleading, but the button was usually set up so the system would be at full speed when the button was "on." Today, the functionality offered by the turbo button is often considered obsolete by manufacturers[citation needed] and has thus disappeared from modern computer models.[dubious – discuss]
- On some video game controllers, a Turbo button or Autofire (sometimes implemented as a sliding switch instead of a button) determines the repeat rate of another action button. For example, the Nintendo Entertainment System's controller has two action buttons, labeled "A" and "B". Normally, pressing the "A" button will result in the action associated with "A" being done once -- for example, a character will jump once. This happens even when the "A" button is "held down" (depressed continually). An enhanced or upgraded controller's "Turbo" function will change this held-down functionality, so that the character would jump repeatedly, as if the "A" button were being pressed many times very quickly (a desirable feature in games where, for example, the "A" button fires a projectile).
