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Pentium 4 Gets 64-bit And Another Core

Intel's 15 Most Unforgettable x86 CPUs

In 2005, Intel improved its Pentium 4 twice. First, with the Prescott-2M, and then with Smithfield. The former was a 64-bit processor, based on the Prescott design, and the latter was a dual-core processor. They are fairly similar and have the same problems as other Pentium 4s: low instructions per cycle (IPC) throughput and difficulty in increasing the clock frequency due to current losses. These two processors, intended to limit losses while awaiting the Core 2 Duo, are not among Intel’s most highly regarded. And while the Pentium D (the commercial name of the Smithfield) does have two cores, in reality it’s an assembly of two Prescott dies in the same package.

Intel Pentium 4
Code name Prescott-2M Smithfield
Date released 2005 2005
Architecture 64 bits 64 bits
Data bus 64 bits 64 bits
Address bus 64 (actual 36) bits 64 (actual 36) bits
Maximum memory 64 GB 64 GB
L1 cache 16 KB + 12 Kµops 2 x 16 KB + 12 Kµops
L2 cache 2,048 KB 2 x 1,024 KB
Clock frequency 3–3.6 GHz 2.8–3.2 GHz
FSB 800 MHz 800 MHz
SMT/SMP Hyper-Threading dual cores (Hyper-Threading on certain models)
Fabrication process 90 nm 90 nm
Number of transistors 169 million 230 million
TDP 84-115 W 95-130 W
Voltage 1.2 V 1.2 V
Die surface area 135 mm² 206 mm²
Connector LGA775 LGA775

An interesting point is that whereas the Pentium 4 processors intended for the consumer market did not use the PAE technology (which enables 36-bit, as opposed to 32-bit memory management) and were therefore limited to 4 GB of RAM, these models can go beyond that limit. In practice, the address bus is still limited to 36 bits (40 bits on the Xeon), but PAE (management in 4 GB pages) is now ancient history—a 64-bit program is capable of making full use of the available memory.

Hyper-Threading, an Intel SMT technology, was available on certain models (Xeon and Extreme Edition). Finally, a 65 nm version (the 9x0 series) of the Pentium 4 was released later, but made no major improvements.

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