Turbo button

On some older IBM PC–compatible computers, the turbo button selects one of two run states: the default "turbo" clock speed or a reduced speed closer to the Intel 8086 CPU. It was relatively common on computers using the Intel 80286, 80386 and 80486 processors, from the mid-1980s to mid-1990s. The name is inspired by the turbocharger, a device which increases an engine's power and efficiency. When pressed, the "turbo" button is intended to let a computer run at the highest speed for which it had been designed.