Introduced on April 22, 2003, Opteron is the name of a line of 64-bit x86 processors produced by AMD. They were the first processors to use the AMD64 instruction set, also known as x86-64. It was designed to compete with Intel's Xeon line of processors.
The Opteron was a significant step forward for 64-bit processors. It was the first 64-bit processor that could natively run 32-bit programs without a speed penalty. Previous 64-bit processors were compatible with 32-bit code, but ran them with degraded speed. Opteron processors allowed users with 32-bit software collections to upgrade to a 64-bit system without sacrificing the performance of their existing software.
Dual-core Opterons were released in 2005, and a series of quad-core Opterons were released beginning in 2007. In 2010, AMD released a series called "Magny-Cours," which had either 8 or 12 cores and used a multi-chip module system. Beginning in 2007, all Opterons include AMD's K10 microarchitecture. K10 provides the functionality of memory prefetching, memory dependence prediction (also known as speculative load), SIMD (single instruction, multiple data) execution, and branch prediction.