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Every x86 processor, including the latest x86_64 bit (unless you have a legacy free machine, but most computers still have a BIOS (or BIOS emulation))
initialise in real mode. The oldest 16 bit mode, in wich they run like the ancient 8086/8088.
I think the speed difference being referred to is related to communicating with the hardware directly in stead of using BIOS calls (which happened in real mode)
The primary difference between Pentiums and newer vs 486 and older was the introduction of Virtual Interrupts. That simplified and sped up the interrupt handling for user mode code, making a significant difference in speed and coding for "enhanced" mode software on the x86. Intel would later work Virtual Ints into certain models of the 486 for people who wished the feature without needing to update the entire computer.
When you see software that runs on a Pentium/586 or better, and not on older hardware, that's usually the hardware that's being relied on that prevents it from being used on the older CPUs. Particularly with OSes, which need to handle both user and kernel modes.




Member since:
2012-02-15
This makes no sense. The 386 and 486 were both fully 32-bit processors.