Hardware Reference
In-Depth Information
Originally, all processors were mounted in sockets (or soldered directly to the mother-
board). However, both Intel and AMD temporarily shifted to a slot-based approach for
their processors in the late 1990s because the processors began incorporating built-in L2
cache, purchased as separate chips from third-party Static RAM (SRAM) memory chip
manufacturers. Therefore, the processor then consisted not of one but of several chips,
all mounted on a daughterboard that was then plugged into a slot in the motherboard.
This worked well, but there were additional expenses in the extra cache chips, the daugh-
terboard itself, the slot, optional casings or packaging, and the support mechanisms and
physicalstandsandlatchesfortheprocessorandheatsink.Allinall,slot-basedprocessors
were expensive to produce compared to the previous socketed versions. With the advent
of the second-generation Celeron, Intel began integrating the L2 cache directly into the
processordie,meaningnoextrachipswererequired.Thesecond-generation (code-named
Coppermine)PentiumIIIalsoreceivedon-dieL2cache,asdidthesecond-generationAth-
lon(code-namedThunderbird)processorfromAMD.Withon-dieL2cache,theprocessor
was back to being a single chip again, which also meant that mounting it on a separate
board plugged into a slot was unnecessary. All modern processors now have integrated
L2 cache (and many high-end processors from Intel and AMD also have large integrated
