[phicoh]

The 286 could still run at a low enough clock speed that changing the clock frequency made sense.

On the 386 that didn't work anymore, but there was an external cache. So typically, the turbo button would disable external cache.

Then the 486 came with built-in L1 cache. And it was always way too fast. At that point the turbo button didn't make sense any more. I guess there were software solutions, but I don't recall any name.

[mlyle]

I turn off 486 cache (in software -- bits in CR0) to run 386 games. Works rather well to hit mid-386 levels of performance.

[TheCycoONE]

As you brought it up, one of the software solutions I used was Mo'Slo. It appears to still have a web presence. http://www.hpaa.com/moslo/

[ant6n]

My family's 486 had a turbo button that switched between 33 and 66 MHz, with the frequency being shiwn on the case like a digital clock.

[caf]

That screen was just telling you whether the switch was on or off, though - the logic to decide what to display was just a series of jumpers in the case front. That's why some were configured to read

  |_| |
  | | |

and

  |   _
  |_ |_|

instead. It's not like it was actually measuring the bus frequency.

[hakfoo]

There was definitely a "cache enable" pin on the 486 socket.

I had a 5x86/133 that had that pin broken. It worked but unimaginably slowly. Wedging a snapped off pin from another CPU into the socket and trying to keep the whole mess bodged/glued/soldered together made it usable again.