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Socket 3 is a central processing unit (CPU), or processor, socket that the world's biggest semiconductor manufacturer, Intel Corporation, introduced in 1991 for its fourth-generation processors that adhere to its x86 instruction set. These personal computer chips are collectively known as the 80486, the i486, or Intel486. Introduced in 1989, the Intel 80486 traces its ancestry to the Intel 8086, or iAPX86, which entered the market in 1978 and is known as the first x86 processor. Socket 3 is notable for being the third 80486 processor-supporting socket, the preceding ones being Socket 1 and Socket 2.
Like other components of its category, Socket 3 functions as a connector on the motherboard that houses the CPU. This forms an electrical interaction between the CPU and the motherboard, which is the "heart" of the computer, and it enables the chip to conduct data transmission with the motherboard. Also, Socket 3 provides physical support and protection for the CPU, securing it on the motherboard and preventing damage during insertion or removal.
Each Socket 3 has 237 pin holes, which serve as the plug-in interface for the processor. These pin holes are neatly arranged in four rows lining its square-like shape in a type of integrated circuit packaging known as pin grid array (PGA). Socket 3 in particular follows a type of PGA form factor standard called plastic pin grid array (PPGA). The socket usually comes with zero insertion force (ZIF), which means that it is designed in such a way that the user requires absolutely no force to plug in or remove the CPU.
Intel introduced Socket 3 as an upgrade of its immediate predecessor Socket 2, which in turn was an upgrade of Socket 1. The inaugural 80486 processor-compatible socket had 169 pin holes. With the Socket 2, Intel added 69 pin holes, as well as compatibility with the Pentium OverDrive, a CPU brand that the company hoped would catch on with customers who wished to get what would become the fifth-generation x86 processors—the original Pentium brand—without upgrading their computers.
Intel made Socket 3 the immediate and more advanced predecessor of Socket 2 by removing a pin hole—Socket 2 has 238—and slightly changing the pin arrangement. This revision permits customers to use processors with an operating voltage of 5 volts (V) as well as with 3.3 V. Socket 3 is not only compatible with Intel 80486 processors such as the 486DX series and its floating-point unit-disconnected 486SX counterpart, but with 80486-compatible CPUs from Intel's main competitor, Advanced Micro Devices (AMD), as well.