The Intel 8086. Intel Core 2 Duo - an example of an x86-compatible, 64-bit multicore processor. AMD Athlon (early version) - another technically different, but fully compatible, x86 implementation. x86
x86-64 x86-64 (also known as x64 ) is a 64-bit extension of IA-32 , the 32-bit generation of the x86 instruction set . It supports vastly larger amounts of virtual memory and physical memory than is possible on IA-32, allowing programs to store larger amounts of data in memory. x86-64 also provides 64-bit general purpose registers and numerous other enhancements. The original specification was created by AMD , and has been implemented by AMD, Intel , VIA , and others. It is fully backwards compatible with 16-bit and 32-bit x86 code. [ 1 ] (p13-14) Because the full x86 16-bit and 32-bit instruction sets remain implemented in hardware without any intervening emulation, existing x86 executables run with no compatibility or performance penalties, [ 2 ] whereas existing applications that are recoded to take advantage of new features of the processor design may achieve performance improvements. Prior to launch, "x86-64" and "x86_64" were used to refer to the instruction set.
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