A 242-pin slot on the motherboard that holds Intel CPU modules including the Intel Single Edge Contact Cartridge (SECC and SECC2) and Single Edge Processor Package (SEPP). The Pentium II was the first to use Slot 1. Slot 1 is a narrow slot like a PCI bus slot, not a small rectangular chip socket. See Slot 2
and Slot A
Slot 1 and Socket 370
This motherboard supports both Slot 1 and Socket 370 for Pentium III chips.