A family of 64-bit x86 CPU chips from AMD, formerly code-named Sledgehammer (part of the Hammer line). Introduced in April 2003, the Opteron fully supports 32-bit applications but requires that programs be optimized and recompiled to take full advantage of the 64 bits. The 64-bit version of Windows, starting with XP, also takes advantage of the increased CPU word size. Intended for servers and high-end workstations, the Opteron competes with Intel's Xeon and Itanium lines. AMD subsequently introduced 64-bit Athlon CPUs (see Athlon). Multicore Opterons In 2005, following the introduction of its Athlon dual-core chips, AMD introduced dual-core Opterons with quad-core compatibility (dual cores could be replaced with quad-core chips on the same motherboard). In 2007, it introduced the quad-core models and later came out with six core and 12-core Opterons. See AMD64, Hammer, Xeon and Itanium.