The turbo button. To PC gamers of a certain age or experience level, hearing that term brings to mind a very specific era in personal computing. From around 1986 to 1995, seeing this button on your computer case was commonplace, and even expected. But, why? What did the turbo button even do? And where did they go, anyway? To get to the bottom of this, we've gotta take a look at the dawn of the modern PC, with the IBM Personal Computer, Model 5150. It was introduced in 1981, and featured a 4.77 MHz Intel 8088 CPU, which is the most pertinent component when it comes to understanding turbo buttons. The IBM PC proved wildly successful, and when people wrote programs and games for it, they assumed that the same 4.77 MHz CPU would be there. The timing of programming routines in software was often tied to this *exact* CPU clock speed, resulting in it playing the same on any IBM PC. Made sense, seeing as the PC only ever came with one CPU up to that point, and when other companies started cloning it, they used a CPU of the same speed, or close to it. But progress doesn't just wait around, especially in technology, and before long, that 4.77 MHz CPU was replaced by an 8 MHz CPU, then 12 MHz, then 16, then 25, 33, 66... eh, you get the idea. Hardware was moving faster than the software could keep up, but PC users still wanted to use their existing games and applications when they upgraded. Yet... there was a *big* problem. Anytime you ran something on a faster machine that relied on a slower CPU speed to run correctly, you ended up with something that looked like this. Uhh, I don't care how fast your reflexes are, that's unusable. So, hardware manufacturers implemented a hardware solution- the turbo button! The name took inspiration from the turbo charger, a device seen in certain automobile engines that increases power and efficiency. Although, personally, I think it was just chosen because it looks cool to have a button that says 'Turbo' on your computer case. Especially because the turbo button doesn't speed things *up*, like a turbo charger, it slows things *down*. Pressing the turbo button would allow you to run these older games and applications that relied on older CPUs in the 4.77 MHz to 8 MHz range simply by limiting the faster processor temporarily. Different manufacturers achieved this in differing ways, from slowing down the clock speed, to disabling the cache and introducing wait states. As a result, calling it a 'turbo' button is a bit counterintuitive. I remember a friend of mine always turning his turbo button on when playing the latest games, then blaming Compaq when it ran so badly. 'Nah, man,' I kept telling him, 'it's because of the turbo button!' Eh, but he said it made no sense, because 'turbo' meant 'fast', and swore that Presarios were just slow and crappy computers. Yeah, whatever, he was like eight. But the point remains- the misnomer was confusing, which led some to reconfigure their machine to have it make more sense. For...
