In old PCs, what was the function of the "Turbo" button?

Now let's learn something A long, long time ago, personal computers used to feature a "Turbo" button alongside the Power and Reset buttons. Ironically, the "Turbo" button functioned opposite to what one might expect today. This button was commonly found on PCs during the 1980s and early 1990s, particularly after the release of the original Intel 8086 processor , which operated at 4.

77 MHz. At that time, many software titles – especially games – were developed with a specific machine in mind and were tied to the specific clock frequency of the CPU to function properly. When faster processors were introduced, these programs ran too fast (yes, that was a thing) because they were designed for slower CPUs.



To address this compatibility issue, the "Turbo" button was introduced to slow down the PC, allowing these programs to run normally at their intended speed. Some computers even supported keyboard combinations like Ctrl-Alt-Plus and Ctrl-Alt-Minus for switching the turbo mode on and off. Often, computer cases also featured a small LED display showing the CPU's clock frequency in MHz or displaying "HI" or "LO" to indicate the mode in which the CPU was running.

The "Turbo" button was very common in 286 and 386 PC clones, less common in 486 PCs, and almost extinct by the time Pentium processors became mainstream in the late 1990s. As technology advanced, software developers began implementing their own timing mechanisms independent of the CPU clock speed. Operating systems like Windows 95 also started handling these compatibility issues internally.

Consequently, the need for a "Turbo" button diminished, and manufacturers phased it out in newer PC models..