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Why doesn't Windows XP run on a 80486 processor?

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Wiki User
2009-10-02 03:01:19

There are several reasons why Windows XP does not run on a

486:

1. Most 486 computers simply cannot support enough memory to run

Windows XP. 64 MB is pretty much the maximum you'd ever find in a

486; 8 to 16 MB is most common.

2. The kernel in Windows XP is SMP-enabled by default. To

support SMP, Windows XP uses an instruction called

CMPXCHG8B, which is only found in Pentium and later

processors.

3. In order to allow for optimizations on-the-fly, such as using

MMX or SSE instructions, Windows XP also requires the CPUID

instruction, which only the later 486 processors had.


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