[fzliu]

> This is because when the power supply is first powering up, even if it only takes a second or two, the CPU has already received "dirty" power, because the power supply was building up a steady stream of electricity. Digital logic chips like CPUs require precise voltages, and they get confused if they receive something outside their intended voltage range.

This is only partially true. When digital chips boot up, gate outputs are in an indeterminate state. The reset sets them to know initial (and valid) values/bits.

[martyvis]

All so called digital devices are really analog devices corralled into operating using binary logic. All it takes is a volt or two applied or removed unexpectedly on those discrete components and you have a bit-flip and possible ensuing mayhem.