Slot 2 was introduced by Intel in 1998 for exclusive use with their Xeon processors. The slot uses the 330 pin SC330 connector, which adds extra pins which become useful for multiprocessor support. The Slot2 interface can be used in 2, 4 or 8 way processor systems.

The pentium II Xeon and pentium 3 xeons are made with a SECC2 format. The SECC2 and Slot2 interface are very large, because of the size the PCB needs to be. Xeon processors use up to 2MB of L2 cache, which is large in size and needs a large area to be placed. The Slot2 interface is only used in high end server systems, and is very expensive.

	RAM	Bus Speed	AGP	# of CPU
Intel 440GX	2GB	100MHz	2X	2
Intel 450NX	8GB	100MHz	no	4

Introduction and Processor Support
The Socket 370 is capable of supporting all socket versions of Intel's Celeron, Celeron II, and Pentium III, as well as VIA's Cyrix III. It was first introduced in April of 1999 to reduce costs that are associated with the SECC packaging that all slot chips require. The onboard L2 cache that all newer chips had would make the packaging a complete waste, so the Socket interface soon returned as the most economical solution.

There are two versions of the Socket370 interface, the early version that was only able to support PPGA socket processors, and the newer version that supports both the PPGA and FCPGA processors. Both interfaces use the identical 370 interface, the only difference lies in the way the processor is manufactured. Flip Chip Grid Pin Array processors are inverted in the interface with the die on top of its host substrate, as opposed to underneath like the PPGA format. This reverses the pins, making it incompatible to some older motherboards. Socket370 was designed to be the economical solution, but because of Slot1 chipset compatibility, it is widely used for even the highest performance chips. The Socket 370 interface uses the same chipsets as the Slot 1 interface.

Introduction and Processor Support
This interface was developed by AMD in July of 1999 for exclusive use with their Athlon processors. AMD was forced to develop their own interface for use with their next generation processor because Intel was reluctant to licence either their Slot1 or Socket370 interface. AMD needed a high performance interface to replace the severely limited Super Socket7 interface. The SlotA uses the same 242 pin SC242 connector, making the interface physically compatible with Slot1 but electrically incompatible and the use of Intel processors impossible.

Features
AMD needed a high performance chipset, so it licenced the EV-6 bus from Digital Equipment Corporations, and this was a major improvement over FSB protocol Intel uses. It allows the first AMD processors to operate on a 100MHz DDR, effectively 200MHz, bus, which was twice as fast as the early Intel chips. SlotA was never able to operate with multiprocessor support because the chipsets were never allowed to evolve enough before being replaced by SocketA.

Chipsets
There were only 2 chipsets ever used with the SlotA interface, one from AMD, and a newer and improved chipset by VIA. Both operate with a 100MHz DDR FSB, ATA66 and only SD RAM.

Chipset	Memory Types	Maxium Memory	AGP	Chipset-FSB Timing
AMD 750	100MHz	768MB	2X	Synchronous
VIA KX133	100-133MHz	2GB	4X	Asynchonous

Socket A

Introduction and Processor Support
AMD has quickly replaced the SlotA interface with the SocketA interface. By using a socket interface for the CPU, the costly slot packaging can be removed, and the CPU can be closer to the chipset allowing for faster FSB speeds. The SocketA interface uses 462 pins and the same 100MHz DDR EV-6 bus as the slot form. This interface is used for only AMD's second generation Athlon, code named Thunderbird, and AMD's Duron processors, because unlike the first generation Athlon, they feature on-die L2 cache, which makes the socket interface possible.

Features
There haven't been any new features which have been added to the current SocketA chipsets over the SlotA interfaces, except allowing for ATA100.

Chipsets
There is currently (August 2000) only one chipset available for the SlotA format, which is VIA's KT133. It is basically the same chipset as the SlotA's KX133, except with a few minor modifications to ensure compatibility. Future chipsets are planned by companies; such as AMD, VIA, and Acer Laboratories (ALi); to be released soon with added that will allow ATA100, DDR DRAM, and multiprocessor configurations.

Chipset	Memory	FSB	# of CPU's
KT133	100, 133MHz	100MHz DDR	1
AMD 760	PC2100	133MHz DDR	1
AMD 760MP	PC2100	133MHz DDR	1-2
VIA K7-DDR	PC2100	133MHz DDR	1
ALiMAGiK 1	PC2100	100MHz DDR	1
RED TEXT denotes unreleased chipsets

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