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  2. x86-64 - Wikipedia

    en.wikipedia.org/wiki/X86-64

    x86-64 (also known as x64, x86_64, AMD64, and Intel 64) [note 1] is a 64-bit version of the x86 instruction set, first announced in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging mode.

  3. x86 - Wikipedia

    en.wikipedia.org/wiki/X86

    The aged 32-bit x86 was competing with much more advanced 64-bit RISC architectures which could address much more memory. Intel and the whole x86 ecosystem needed 64-bit memory addressing if x86 was to survive the 64-bit computing era, as workstation and desktop software applications were soon to start hitting the limits of 32-bit memory ...

  4. 64-bit computing - Wikipedia

    en.wikipedia.org/wiki/64-bit_computing

    Some 64-bit architectures, such as x86-64 and AArch64, support more general-purpose registers than their 32-bit counterparts (although this is not due specifically to the word length). This leads to a significant speed increase for tight loops since the processor does not have to fetch data from the cache or main memory if the data can fit in ...

  5. x86 memory segmentation - Wikipedia

    en.wikipedia.org/wiki/X86_memory_segmentation

    The x86-64 architecture does not use segmentation in long mode (64-bit mode). Four of the segment registers, CS, SS, DS, and ES, are forced to base address 0, and the limit to 2 64. The segment registers FS and GS can still have a nonzero base address.

  6. Long mode - Wikipedia

    en.wikipedia.org/wiki/Long_mode

    In the x86-64 computer architecture, long mode is the mode where a 64-bit operating system can access 64-bit instructions and registers. 64-bit programs are run in a sub-mode called 64-bit mode, while 32-bit programs and 16-bit protected mode programs are executed in a sub-mode called compatibility mode.

  7. Comparison of instruction set architectures - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_instruction...

    Computer architectures are often described as n-bit architectures. In the first 3 ⁄ 4 of the 20th century, n is often 12, 18, 24, 30, 36, 48 or 60.In the last 1 ⁄ 3 of the 20th century, n is often 8, 16, or 32, and in the 21st century, n is often 16, 32 or 64, but other sizes have been used (including 6, 39, 128).

  8. x86 instruction listings - Wikipedia

    en.wikipedia.org/wiki/X86_instruction_listings

    existing instructions extended to a 64 bit address size (JRCXZ) existing instructions extended to a 64 bit operand size (remaining instructions) Most instructions with a 64 bit operand size encode this using a REX.W prefix; in the absence of the REX.W prefix, the corresponding instruction with 32 bit operand size is encoded. This mechanism also ...

  9. FLAGS register - Wikipedia

    en.wikipedia.org/wiki/FLAGS_register

    The PUSHF and POPF instructions transfer the 16-bit FLAGS register. PUSHFD/POPFD (introduced with the i386 architecture) transfer the 32-bit double register EFLAGS. PUSHFQ/POPFQ (introduced with the x86-64 architecture) transfer the 64-bit quadword register RFLAGS. In 64-bit mode, PUSHF/POPF and PUSHFQ/POPFQ are available but PUSHFD/POPFD are not.