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.
| 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 |
| 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 |
| 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.
