The CPU interface is important to the operation of the CPU. It is the physical connection between the processor and the motherboard. As processors improve, so do the CPU interfaces. More pins may be added to the interface to support the advanced features of the processor, or pins may be removed for simplicity when they are no longer needed.

Very First Interfaces
The very first processors didn't use a real interface, they were physically connected to the motherboard and unmoveable from their position. There became a need for upgrading of processors, and without an interface, this required the unsoldering and then resoldering of the processor from the mainboard. Chips as early as the 486 started to use a socket interface to connect the chips to the main board. This meant that the chips pins no longer needed to be soldered to the mainboard, instead they could be easily fit into a snug plastic Zero Insertion Force (ZIF) interface that would allow them to be easily removed or replaced at will.

The older chipsets are no longer used because they were only made to support specific processors. Below is a small chart to aid in identification and comparison.

Interface	Supported CPU(s)	Pins
Socket 1	i486	169
Socket 2	i486, Pentium Overdrive	238
Socket 3	i486, Pentium Overdrive, AMD 5x86	237
Socket 4	Pentium 60, 66, and Overdrive	273
Socket 5	Pentium 75 to 133MHz	320
Socket 6	All 486 processors	235

Chipsets
Chipsets are in charge of making the computer work. System features are limited more by the chipset used then be what processor is plugged into the board. Chipsets are in charge of memory address translating, request buffering and queuing, data bus control, frequency timing, and protocol translations - just to name a few. Since the processor isn't capable of handling these tasks, newer future processors like AMD's K8/Sledghammer chip will be designed with an integrated chipset so that it has more control over the rest of the system operations. An integrated chipset would allows for faster performance because it totally eliminates a device, but would make the processor overly complex and large in size Having a chipset integrated into the processor requires advanced production technology and a very small processor fabrication size.

Introduction and Processor Support
This was first introduced in 1995 with the pentium processor. It is equipped with 296 pins, and supports the pentium, pentium MMX, K5, K6, and Cyrix M1.

Features
The Socket 7 interface featured support for motherboard L2 cache which operated at system bus frequency. This was a major downside for the Socket7 interface, because this low-speed cache was a major bottleneck for system performance.

The Sockt7 interface was equipped with a PCI only chipset with up to 512k of L2 cache on the motherboard, which shared memory bandwidth on the 66MHz front side bus. The FSB was later able to operate at the unofficial and unsupported 75MHz and 83MHz bus speeds. It was up to the end user to modify and use these settings, because they would run the system out of specification.

Chipset History & Socket 7 | Super7 & Socket 8 | Slot 1 | Slot2, Socket370, SlotA, & SocketA