On: Examining the silicon dies of the Intel 386 proces...

[srejk]

Great post! Any idea how the turbo button worked? It seems like, given the transistor difference between the 8086 and 386, that merely decreasing the clock frequency wouldn't be enough?

[kens → srejk]

Yes, I think the turbo button just changes the clock speed. The 386 was designed to be binary compatible with the 8086, but normally ran faster.

[fsckboy → srejk]

the lack-of-turbo button was included to enhance compatibility with older software that using timing tricks that relied on the clockspeeds of the older generations of processors. Those older processors would not have used the enhanced features of the new processors, just the backward compatible features. Turbo was a motherboard OEM feature, not a 386 feature. Otherwise, there was no reason not to run "turbo"

[rasz → srejk]

Chipset/motherboard specific. Clock, wait states, cache, later even SMM sleep.

[irdc → srejk]

This was often done by introducing wait states, so the processor would slow down while accessing main memory.

[sounds → irdc]

I did some sleuthing to try to figure out what part of computing history this could refer to.

- Maybe because one could lower the "wait states" BIOS setting on PCs, and this became a selling point and was marketed? https://retrocomputing.stackexchange.com/questions/9779 https://retrocomputing.stackexchange.com/questions/18333

Note: it is often perceived that the CPU with more "wait states" was slower. But the above links point out how often the opposite is true.

- The Apple II era was a very different world. The CPU was relatively slower than the RAM. https://retrocomputing.stackexchange.com/questions/23541