Socket 478 (also known as mPGA478 or mPGA478B) is 478 contact CPU socket used for Intel's Pentium 4 and Celeron series CPUs. Socket 478 was phased out with the launch of LGA 775.
Socket 478 has been used for all of the Northwood Pentium 4s and Celerons, the first Prescott Pentium 4s, and all Willamette Celerons and some Willamette Pentium 4s. Socket 478 also supports newer Prescott Celeron Ds, and early Pentium 4 Extreme Edition processors with 2MB of L3 cache. The socket was launched with the Northwood core to compete with AMD's 462-pin Socket A and their Athlon XP processors. Socket 478, which accommodates high and low-end proscessors, was also the replacement for Socket 423, a Willamette processor socket which remained in the market for only a short time.
Celeron Ds are also available for Socket 478 and were the last CPUs made for the socket.
While the Intel mobile CPUs are available in 478-pin packages, they in fact only operate in a range of slightly differing sockets, Socket 479, Socket M, and Socket P, which are also incompatible with each other.
