Processor Slots

Processor Slots

After introducing the Pentium Pro with its integrated L2 cache, Intel discovered that the physical package it chose was very costly to produce. Intel was looking for a way to easily integrate cache and possibly other components into a processor package, and it came up with a cartridge or board design as the best way to do this. In order to accept its new cartridges, Intel designed two different types of slots that could be used on motherboards.
Slot 1 is a 242-pin slot that is designed to accept Pentium II, Pentium III, and most Celeron processors. Slot 2 is a more sophisticated 330-pin slot that is designed for the Pentium II and III Xeon processors, which are primarily for workstations and servers. Besides the extra pins, the biggest difference between Slot 1 and Slot 2 is the fact that Slot 2 was designed to host up to four-way or more processing in a single board. Slot 1 only allows single or dual processing functionality.
Note that Slot 2 is also called SC330, which stands for Slot Connector with 330 pins.

Slot 1 (SC242)

Slot 1, also called SC242 (Slot Connector 242 pins), is used by the SEC (Single Edge Cartridge) design used with the cartridge-type Pentium II/III and Celeron processors. Inside the cartridge is a substrate card that includes the processor and L2 cache. Unlike the Pentium Pro, the L2 cache was mounted on the circuit board and not within the same chip package as the processor. This allowed Intel to use aftermarket SRAM chips instead of making them internally and also allowed it to make processors with different amounts of cache easily. For example, the original Celeron was created by taking a Pentium II and simply leaving out the external cache chips.