The Intel® Core™ Duo processor is a new member of the Intel® mobile processor product line. It is the first Intel® mobile microarchitecture that uses CMP (multi cores on die) technology. Building a general-purpose mobile core is a challenging task since, on the one hand, the system needs to maintain the highest level of performance, while on the other hand, the system must fit into different thermal envelopes, as illustrated by Figure 1, and improve power efficiency.

Intel® Core™ Duo is based on Pentium® M processor 755/745 core microarchitecture with few performance improvements at the level of each single core. The major performance boost is achieved from the integration of dual cores on the die (CMP architecture). This agrees with our assessment that continuing to improve single thread performance is rather costly in terms of power and may achieve diminishing returns in terms of efficiency, if major microarchitecture enhancements are not made. The big potential for improved performance is through exploring parallelism between threads. However, the CMP architecture presents many challenges for power and thermal control to still fit into the mobility constraints.

Figure 1: Products using different thermal envelopes *
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In this paper we present the new Intel® Core™ Duo microarchitecture and show how the need to target power-efficient general-purpose processors has affected many of our decisions. We provide a general overview of the different ingredients of the Intel® Core™ Duo system, while the other papers in this issue of the Intel® Technology Journal focus on more specific aspects of the system such as the CMP microarchitecture and the power and thermal control methods.

Figure 2: Intel® Core™ Duo processor floor plan
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As Figure 2 shows, Intel® Core™ Duo technology is based on two enhanced Pentium M cores that were integrated and use a shared L2 cache. The way we integrated the dual core in the system had a major impact on our design and implementation process. In order to meet the performance and power targets we aimed to do the following:

• Keep the performance similar to or better than that of single thread performance processors in the previous generation of the Pentium M family (that use the same-size L2 cache).
• Significantly improve the performance for multithreaded and multi-processes software environments.
• Keep the average power consumption of the dual core the same as previous generations of mobile processors (that use a single core).
• Ensure that this processor fits in all the different thermal envelopes the processor is targeted to.

In this paper we provide a high-level description of the main Intel® Core™ Duo features and discuss how each feature fits into the targets of the various projects.