Yonah (microprocessor)

Yonah (microprocessor). Yonah was the code name for Intel's first generation of 65 nm process dual-core mobile processors, introduced in early 2006. It represented a significant shift from the single-core Pentium M lineage, bringing true symmetric multiprocessing to notebook platforms and serving as the foundation for the new Intel Core brand. The architecture was primarily featured in the Intel Core Duo and Intel Core Solo product lines, as well as in certain Xeon and Celeron variants.

Overview

The development of Yonah was driven by the need for improved performance-per-watt in the mobile computing segment, a market where Intel competed fiercely with AMD's Turion 64 mobile processors. It was the culmination of the Pentium M microarchitecture lineage that originated with Banias and was refined in Dothan. The launch of Yonah coincided with Apple's historic transition from PowerPC processors to Intel chips, with Yonah-based MacBook Pro and iMac models being among the first Macs to use Intel silicon. This processor family was manufactured using a 65 nm process technology at Intel's fabrication plants.

Architecture

Yonah's architecture was an enhanced, dual-core evolution of the Pentium M design rather than a completely new microarchitecture. It featured a shared L2 cache (Smart Cache) of up to 2 MB that could be dynamically allocated between the two cores, improving efficiency over separate caches. The front-side bus speed was increased to 667 MT/s, and the design included support for Intel 64 (the x86-64 implementation) only in server-oriented Xeon versions, not in standard mobile chips. Key enhancements also included improved Digital Media Boost capabilities and more advanced power management states, building upon the Enhanced Intel SpeedStep Technology from earlier mobile processors.

Processor cores

The Yonah design contained two processor cores on a single die, each based on the proven Pentium M execution core. These cores supported Intel's Hyper-Threading Technology, but it was disabled in all shipping products to optimize thermal and power characteristics. The cores operated within a single voltage and frequency domain, meaning both cores ran at the same clock speed. The shared L2 cache utilized an advanced arbitration mechanism to minimize latency and reduce off-die memory traffic to the DDR2 memory controller within the supporting 945 Express chipset.

Performance and power characteristics

Yonah delivered substantially improved multi-threaded performance over its single-core predecessors while maintaining excellent power efficiency for its time. Typical Thermal Design Power (TDP) for standard voltage parts ranged from 31 watts, with low-voltage and ultra-low-voltage variants consuming significantly less. This efficiency was crucial for the growing market of thin-and-light notebooks and helped Intel compete in segments targeted by Transmeta's earlier low-power designs. Performance in applications optimized for multithreading, such as video encoding and certain professional software, saw notable gains.

Market positioning and variants

Yonah was marketed under several brands targeting different segments of the market. The flagship brand was Intel Core Duo, encompassing standard dual-core parts, while single-core derivatives were sold as Intel Core Solo. Entry-level markets were served by the Celeron M brand, and a version with support for ECC memory was offered as the Xeon LV for embedded and server applications. These processors were paired with the 945GM, 945PM, and 945GMS chipsets. A notable variant was the Core Duo T2600, which was used in the first-generation MacBook Pro.

Successors and legacy

Yonah was succeeded later in 2006 by the Core microarchitecture, first implemented in the Merom mobile processor. This successor introduced a full 64-bit instruction set to the mainstream mobile lineup, a wider microarchitecture with a 14-stage pipeline, and other major enhancements like Intel Wide Dynamic Execution. The Yonah design itself was briefly adapted for the desktop market as the Pentium Dual-Core series (codenamed Presler in a different form). Yonah's legacy is as the direct architectural bridge between the Pentium M and the revolutionary Core microarchitecture that restored Intel's performance leadership over AMD across desktop, mobile, and server markets. Category:Intel microprocessors Category:Computer-related introductions in 2006