The Pentium® and Pentium® Pro Sockets
The Pentium® and Pentium® Pro processors utilized PGA (i.e., Pin Grid Array) packages and were installed into a PGA socket on the system board. The Pentium® sockets were referred to as sockets 1 through 7, with socket 7 being the de facto standard on most Pentium® system boards. The Pentium® Pro processor implemented the socket 8 PGA. System board designers could license Socket 8 from Intel®, but processor designers could not.
It stands to reason that Intel® must have had a good reason for switching from the compact PGA package to the rather large cartridge. At that time, the silicon wafer and die layout processes in use were rather coarse when compared to today's technologies. This ...