Processor Types and Specifications - Upgrading and Repairing PCs - page 137

• A superscalar, fully pipelined floating-point calculation unit —This provides faster
operationsperclockcycleandcuresalong-timedeficiencyofAMDprocessorsversus
Intel processors.
• A hardware data prefetch —This gathers the data needed from system memory and
places it in the processor's Level 1 cache to save time.
• Improved translation look-aside buffers (TLBs) —These enable the storage of data
where the processor can access it more quickly without duplication or stalling for lack
of fresh information.
Thesedesignimprovementswringmoreworkoutofeachclockcycle,enablinga“slower”
Athlon XP to beat a “faster” Pentium 4 processor in doing actual work.
The first models of the Athlon XP used the Palomino core, which is also shared by the
Athlon4mobile(laptop)processor.LatermodelshaveusedtheThoroughbredcore,which
waslaterrevisedtoimprovethermalcharacteristics.ThedifferentThoroughbredcoresare
sometimes referred to as Thoroughbred-A and Thoroughbred-B. Athlon XP processors
use a core with 512KB on-die full-speed L2 cache known as Barton . Additional features
include the following:
• 3DNow! Professional multimedia instructions (adding compatibility with the 70 addi-
tional SSE instructions in the Pentium III but not the 144 additional SSE2 instructions
in the Pentium 4)
• 266MHz or 333MHz FSB
• 128KB Level 1 and 256KB or 512KB on-die Level 2 memory caches running at full
CPU speed
• Copper interconnects (instead of aluminum) for more electrical efficiency and less
heat
Also new to the Athlon XP is the use of a thinner, lighter organic chip packaging com-
pound similar to that used by Intel Pentium 4 processors. Figure 3.35 shows the Athlon
XP processor that use the Barton core.
Figure 3.35 AMD Athlon XP 0.13-micron processor with 512KB of L2 cache for Socket A (PGA form
factor).