A multi-core processor (or chip-level multiprocessor, CMP) combines two or more independent cores (normally a CPU) into a single package composed of a single integrated circuit (IC), called a die, or more dies packaged together. A dual-core processor contains two cores, and a quad-core processor contains four cores. A multi-core microprocessor implements multiprocessing in a single physical package. A processor with all cores on a single die is called a monolithic processor. Cores in a multicore device may share a single coherent cache at the highest on-device cache level (e.g. L2 for the Intel Core 2) or may have separate caches (e.g. current AMD dual-core processors). The processors also share the same interconnect to the rest of the system. Each "core" independently implements optimizations such as superscalar execution, pipelining, and multithreading. A system with cores is effective when it is presented with or more threads concurrently. The most commercially significant (or at least the most 'obvious') multi-core processors are those used in personal computers (primarily from Intel and AMD) and game consoles (e.g., the eight-core Cell processor in the PS3 and the three-core Xenon processor in the Xbox 360). In this context, "multi" typically means a relatively small number of cores. However, the technology is widely used in other technology areas, especially those of embedded processors, such as network processors and digital signal processors, and in GPUs.
