Dictionary of Computer and Internet Terms: x64
x64
a 64-bit extension of the Pentium (32-bit)CPUarchitecture originally developed by AMD for the Athlon 64 processor, and then adopted by Intel; the two companies'versions, which are compatible but may differ slightly, are known as AMD64 and EM64T respectively. Unlike IA-64 (Itanium), x64 is completely compatible with unmodified Pentium software; programmers can take advantage of the additional 64-bit instructions if they wish. Thus, x64 extends the Pentium the same way the Pentium extended the earlier 80286.
