This
SEC slot was used originally for
Intel's
Pentium II CPUs. Later, they then used this slot for their
Celerons and
Pentium 3s before they began to use
Socket 370 for both. (Note: This is in a similar fashion to their using SEC
Slot 2 for the "P3"
Xeons and then changing the interface to a
FCGA socket for the newer ones.
It is probably also worth noting that
AMDs
Slot A interface is a mirror of Intel's
Slot 1 (as they couldn't copy it -- see the above write-up). This interface was also then changed to a socket type interface:
Socket A (
Socket 462), which AMD used right through to their
Athlon XP (
Palamino) processors.