CPUs 8086 (1978) Added flags80286 (1982) Extended registers to 32-bits80386 (1985) Added 80-bit floating point registers80486 (1989) Added flagsPentium (1993) Added 64-bit floating point registersPentium MMX (1996) Added 128-bit SIMD registersPentium III (1999) Extended registers to 64-bitsAthlon 64 (2003) Added 256-bit SIMD registersCore ix 2k (2011) Legend 8-bits 16-bits 32-bits 64-bits 80-bits 128-bits 256-bits Status register General purpose registers Segment selectors Program counter Instruction PointerIP FLAGS Instruction PointerEIP EFLAGS Floating point registers SIMD registers Instruction PointerRIP RFLAGS