Intel Core
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- This article is about Intel processors branded as "Intel Core", such as the 65 nanometre processor codenamed Yonah and its variants. For the microarchitecture to be used in future Intel Core microprocessors, see Intel Core Microarchitecture. For Intel processors branded as "Intel Core 2", see Intel Core 2.
 
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Yonah
Yonah was the code name for Intel's first generation of 65 nm process mobile microprocessors, based on the Banias/Dothan Pentium M microarchitecture, incorporating LaGrande security technology. SIMD performance has been improved through the addition of SSE3 instructions and improvements to SSE and SSE2 implementations, while integer performance decreased slightly due to higher latency cache. Additionally, Yonah includes support for the NX bit.Core Duo is the world's first low-power (less than 25 watts) Dual Core microprocessor, with the previous low being the Opteron 260 and 860 HE at 55 watts. Core Duo was released on 5 January 2006, with the other components of the Napa platform. It is the first Intel processor to be used in Apple Macintosh products (the Apple Developer Transition Kit machines, non-production units distributed to some developers, used Pentium 4 processors).
Contrary to early reports, the Intel Core Duo supports Intel's Vanderpool virtualization technology, except in the T2300E model, as indicated by [the Intel Centrino Duo Mobile Technology Performance Brief] and [Intel's Processor Number Feature Table]. However, it seems some vendors have chosen to disable this feature by default, making it available through a BIOS option.
EM64T (Intel x86-64 extensions) is not supported by Yonah. However, EM64T support is planned for Yonah's successor, Core 2, code-named Merom.
Intel Core Duo consists of two cores, a 2 MiB L2 cache shared by both cores, and an arbiter bus that controls both L2 cache and FSB access. Upcoming steppings of Core Duo processors will also include the ability to disable one core to conserve power.
Intel Core Solo uses the same two core die as the Core Duo, but features only one active core. (There is still high demand for single-core mobile processors, and it is easier for Intel to disable one of the cores of the existing dual-core design than to launch a new production line of CPUs that physically only have one core. Additionally, this allows Intel to sell CPUs that didn't pass quality control because one of the cores was defective by disabling it.)
Technical specifications
Core Duo contains 151 million transistors, including the shared 2 MiB L2 cache. Yonah's execution core contains a 12 stage pipeline, forecasted to eventually be able to clock to 2.33–2.50 GHz of maximum frequency. The communication between the L2 cache and both execution cores is handled by an arbitration bus unit, which eliminates cache coherency traffic over the FSB, at the expense of raising the core-to-L2 latency from 10 clock cycles (in the Dothan Pentium M) to 14 clock cycles. The increase in clock frequency offsets the impact of the increased clock cycle latency. The power management components of the core features improved grained thermal control, as well as independent scaling of power between the two cores, resulting in very efficient management of power.Core processors communicate with the system chipset over a 667 MT/s front side bus (FSB), up from 533 MT/s used by the fastest Pentium M.
Yonah is supported by the 945GM, 945PM and 945GT system chipsets. Core Duo and Core Solo use an FCPGA6 (478-pin) pinout, but due to pin arrangement and new chipset functions are not compatible with any previous Pentium M motherboard.
The T2300E, was later introduced as a replacement for the T2300. It has dropped support for Virtualization Technology. Early Intel specifications mistakenly claimed a halving of the Thermal Design Point.
Advantages and shortcomings
In many categories of performance (which support both cores), Yonah represents an uncharacteristically large improvement over its immediate predecessor:
- two computational cores with no significant increase in power consumption
- outstanding performance
- outstanding "performance per watt" ratio
- high memory latency due to the lack of on-die memory controller (further aggravated by system-chipset's use of DDR-II RAM)
- poor Floating Point Unit (FPU) throughput due to the smaller number of FP units in each CPU core.
- no 64-bit (EM64T) support
- same or even slightly worse "performance per watt" in single threaded applications compared to its predecessor.
Many feel that Yonah's lack of 64-bit support will be a significant limitation in the future. However, support for 64-bit operating systems is currently limited in the consumer retail market, a situation unlikely to change until the release of Windows Vista in early 2007. Also, few laptops support more than 2 GB of RAM, negating the memory aspect of 64-bit support. Hence, many people believe that for its intended market (mobile and laptop PCs) the lack of EM64T seems inconsequential at the moment.
The Sossaman processor for servers, which is based on Yonah, also lacks EM64T-support. For the server market, this has more severe consequences, since all major server operating systems already support EM64T, and the upcoming Exchange 12 even requires a 64-bit processor to run.
For these reasons, some consider Core to be a temporary stopgap measure, bridging the brief interregnum between the Pentium series and the 64-bit Intel Core 2 CPUs, which ship in summer 2006.
According to Mobile Roadmaps from 2005, Intel originally seems to have focused more on the power consumption of its p6+ Pentium M and Core processors and aimed to reduce it by 50% with Yonah. Intel originally planned to continue offering desktop (NetBurst) derivations with reduced power consumption for mobile performence solutions and only use p6+ Pentium M/Core processors as medium-to-low performance, low power consumption parts. The policy was apparently changed later on to trying to keep the power consumption more or less at the same level and increasing the performance by as much as possible. This change in policy probably resulted from Intel's changed policy of abandoning NetBurst and replacing it with p6+ Pentium M/Core. This meant a shift in priority of the p6+ Pentium M/Core more towards high performance and less towards low power consumption.
Sossaman
A derivative of Yonah, code-named Sossaman, was released on 14 March 2006 as the Dual-Core Xeon LV. Sossaman is virtually identical to Yonah, except that Sossaman supports dual-socket configurations (for a total of 4 cores) and implements 36-bit memory addressing (PAE mode).
Successor
The successor to Core will be the Intel Core 2 line of processors using cores based upon the Intel Core Microarchitecture, scheduled for release in mid 2006. The release of Intel Core 2 will mark the reunification of Intel's desktop and notebook product lines as Core 2 processors will be released as both dual and single-core products for desktops and notebooks, unlike the first Intel Core CPUs that were targeted only for notebooks.
See also
External links
- [Intel Core Duo Web page]
- [Intel Core Solo Web page]
- [Processor comparison table]
- [Intel Core technical specifications]
- [techPowerUp! CPU Database]
- [Some Core Duo Specs]
- [Tested] against AMD's 64 X2 line and Intel's own Pentium M
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