Pentium 4 Gets 64-bit And Another Core
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.
|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|
|SIMD||MMX, SSE, SSE2, SSE3||MMX, SSE, SSE2, SSE3|
|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|
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.