Slot 1

Slot 1 refers to the physical and electrical specification for the connector used by some of Intel's P6 microarchitecture processors, including the Pentium Pro, Celeron, Pentium II and the Pentium III and marked the beginning of AwardBIOS v6.00PG with support on some later boards. Both single and dual processor configurations were implemented. The form factor used for Slot 1 was a 5-inch-long, 242-contact edge connector named SC242. To prevent the cartridge from being inserted the wrong way, the slot was keyed to allow installation in only one direction. SC242 was also used for AMD's Slot A for early versions of their Athlon CPUs, though while the two slots were identical mechanically, they were electrically incompatible. To discourage Slot A users from accidentally installing a Slot 1 CPU on a Slot A motherboard, the connector was rotated 180 degrees. This also allowed motherboard manufacturers to save costs by stocking the same part for both Slot 1 and Slot A assemblies. Intel went back into using a traditional socket interface with Socket 370 in 1999.