Multi-core processor: Difference between revisions

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A '''dualmulti-core''' [[central processing unit|CPUmicroprocessor]] is one which combines two or more independent processors andinto theira respectivesingle [[CPUpackage, cache|cache]]s and cache controllers ontooften a single silicon chip, or [[integrated circuit]] (IC). [[IBM]]'s [[POWER4|POWER4]] was the first microprocessor to incorporate 2 cores onSimilarly, a single die. Various '''dual-core''' CPUsdevice arecontains beingonly developedtwo byindependent companiesmicroprocessors. such asIn [[Motorola]]general, [[Intel]]multi-core andmicroprocessors [[AMD]],allow anda begancomputing device to appearexhibit insome consumerform products inof [[2005thread-level parallelism]]. without Thisincluding ismultiple an initial stepmicroprocessors in the development of [[multicore|many core]]separate computerphysical architecturespackages.

There is some discrepancy in the semantics by which the terms "multi-core" and "dual-core" are defined. Most commonly they are used to refer to some sort of [[central processing unit]] (CPU), but are sometimes also applied to [[DSP]]s and [[System-on-a-chip|SoC]]s. Additionally, some use these terms only refer to multi-core microprocessors that are manufactured on the ''same'' integraded circuit die. These persons generally prefer to refer to separate microprocessor dies in the same package by another name, such as '''"multi-chip module"''', '''"double core"''', or even '''"twin core"'''. <!-- Can we get examples of these last two? --> This article uses both the terms "multi-core" and "dual-core" to reference microelectronic CPUs manufactured on the ''same'' integrated circuit, unless otherwise noted.

Some people think a true dual-core processor has two cores on a die (and the die is wrapped in a package). Some other people (like Intel) think a dual-core also includes a processor which has one core on each die, and the two dies are on the same package that plugged in one socket on the motherboard. Some call the latter multichip module, double core, or twin core, instead of dual-core. And in the discussion of [[multicore]], the meaning of 'processor', 'CPU', 'chip' depends on the context; each may mean a core, a die, or a package.

[[Image:Dual Core Generic.png|thumb|190px|Conceptual diagram of a dual-core chipCPU, with CPU-local Level 1 caches, and shared, on-chip Level 2 caches.]]

Dual-core CPU technology first became a practical viability in [[2001]]{{ref|DSP}} as 180-[[nanometre|nm]] [[CMOS]] process technology became feasible for volume production. At this size, multiple copies of the largest microprocessor architectures could be incorporated onto a single production die. (Alternative uses of this newly available "real estate" include widening the bus and internal registers of existing CPU cores, or incorporating more high-speed cache memory on-chip.)