Function:

Identifies CPU and revision information for the installed CPU. Note that
Intel officially introduced CPUID only with the Pentium processor.
It seems the instruction was unofficially introduced in the later
486 CPUs as well. Discovered by Christian Ludloff (see acknowledgements).
Supported by the UMC U5S 486 clones as well.

Executing it on an early 486 yields an Invalid Opcode Exception.
To safely use this instruction, an exception handler must be installed.
A safer workaround though is to test whether the ID bit in EFLAGS is set.
If so, the CPU supports CPUID. See <EFLAGS> image.

The instruction expects input in the EAX register and outputs information
in the EAX, EBX, ECX and EDX registers.