PC Hardware Architectures

As a rule, code for older CPUs will run on newer CPUs, but not the other way

i386	the old 386 and 486 CPUs
i586	Pentium, Pentium Pro, 100% AMD compatibles (e.g. K5, Cyrix)
i686	Pentium II, P3, AMD Athlon, Duron, T-bird, XP