Socket S1 is the CPU socket type used by AMD for their Turion 64, Athlon 64 Mobile, Phenom II Mobile and later Sempron processors, which debuted with the dual-core Turion 64 X2 CPUs on May 17, 2006.

Socket S1 is a 638 pin, low profile, ZIF, 1.27mm pitch socket.

[1] It replaces the existing Socket 754 in the mobile computing segment (e.g. laptops) as well as the microPGA Socket 563 form factor.

Socket S1 CPUs can include support for dual-channel DDR2 SDRAM, dual-core mobile CPUs, and virtualization technology, and compete with the mobile Intel Core 2 processor series.

[2] Different generations of processors used various pinouts of the S1 socket; processors were not necessarily electrically-compatible with each socket even if they fit mechanically.