A turbo button
refers to a button
A push-button or simply button is a simple switch mechanism for controlling some aspect of a machine or a process. Buttons are typically made out of hard material, usually plastic or metal. The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed...
on a piece of electronic equipment, which makes the equipment run faster (or slower) in some way. Although the name is based on that of a forced induction air compressor which makes a car go faster, automotive turbochargers
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
are not manually operated, but are directly linked to the engine's output.
On personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
s, 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.
Some systems also supported keyboard combinations -- and -- for switching turbo mode on and off; ITT Xtra used -- to toggle.
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". The turbo button was often linked to a MHz LED display on the system case, or to a "hi"/"lo" LED display.
While the implementation of the turbo button by manufacturers has all but disappeared, software developers have compensated with software replacements. One example is DOSBox
DOSBox is emulator software that emulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old PC games. DOSBox is free software....
(see ), which offers full turbo button functionality with adjustable clock speed. Modern PCs that support ACPI
ACPI may refer to:*Advanced Configuration and Power Interface for computer configuration and management*Animation Council of the Philippines, Inc....
power management may provide software controls to switch ACPI performance states or other CPU throttling modes.
Some keyboards have "Turbo" buttons that adjust the computer performance or the keyboard repeat rate.
On some video game controllers, a Turbo button
(sometimes implemented as a sliding switch instead of a button) determines the repeat rate of another action button. For example, the Nintendo Entertainment System
The Nintendo Entertainment System is an 8-bit video game console that was released by Nintendo in North America during 1985, in Europe during 1986 and Australia in 1987...
'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 or rapid pressing of a button is required).