Intel's original 64bit extensions for x86
5 hours ago
- #Intel
- #Computer Architecture
- #x86-64
- Intel developed a 64-bit extension for x86 processors as a backup to Itanium (IA-64) in the late 1990s, but it was never released due to marketing concerns.
- AMD announced AMD64 in 1999, which overshadowed both Itanium and Intel's internal 64-bit extension, leading Intel to adopt AMD's design in 2004.
- Intel's 64-bit extension design, detailed in patents from 2000 and 2003, used undefined addressing modes to expand register sets, differing from AMD's REX prefix approach.
- Intel's design potentially allowed for future expansion to 32 registers, though initial implementations might have been limited to 16.
- There is limited information on how closely Intel's patents matched the fused-off functionality in their processors.