Wednesday, April 1, 2015

Pentium Dual Core processor (CPU)

Pentium Dual Core processor (CPU)

The Pentium Dual Core is the Intel brand covering their low price dual core processor range used in notebook computers. As the name suggests, it has two processor cores executing in parallel using the same shared memory. The Pentium Dual Core was originally based on the Core Duo but more recently we have seen releases based on the Core 2 Duo.
The new Pentium Dual Core brand appeared in notebook computers in early 2007 as the processors T2060, T2080, and T2130 based on the 32-bit Yonah core derived from the Pentium M. They closely resemble the Core Duo T2050 processor with the exception of having 1 MB L2 cache instead of 2 MB, and a 533 MHz FSB. Subsequent Pentium Dual Core processors based on Core 2 Duo were released in the form of the T2310, T2330, and T2370 (see table below) in Q4 2007. These processors are based on the Merom, which is Intel’s mobile version of the Core 2 Duo, and again, have only 1MB of L2 cache enabled and run at a lower clock speed than their Core 2 Duo counterparts. The T4xxx Series Pentium Dual Cores is based on the Penryn core with 800 MHz FSB and produced in 45nm. The 2nd level cache is still 1MB.
Clearly, by using a lower clock frequency and half the available L2 cache, the Pentium Dual Core is targeted at the lower end of the Notebook market leaving the Core brand to the higher end (see below for how the Pentium Dual Core brand also sources the desktop market). These restrictions noticeably affect the performance of the processor, but then it is very reasonably priced compared to its nearest competitors.

Key Features

  • Dual core processor with 1MB shared level 2 cache
  • 533 / 800 MHz external bus (Yonah & Merom / Penryn)
  • Execute Disable Bit
  • SSE3 instruction set
  • Intelligent Power Capability
  • Enhanced SpeedStep Technology
  • Socket 775
  • Advanced Thermal Manager
  • Dynamic Power Coordination

Performance

The nearest rival to the Pentium Dual Core processors is the AMD Turion 64 X2. Our own test results show the Core 2 Duo outperforms both the Core Duo and the AMD Turion 64 X2, but that doesn’t take into account the reduced clock speed and L2 cache memory, which is discussed further on !
The Intel Core 2 Duo (Merom) employs 64-bit operation compared to the 32-bit Core Duo derived-Yonah. Its main processing gain comes from a widening of its internal datapaths and the inclusion of more of just about everything that has been proven to work in earlier Intel designs. That and algorithmic improvements in speculative execution, data flow analysis, out of order execution, and the pattern-matching algorithm in the CPU prefetch unit more than compensate for its increased execution pipeline of 14 stages compared to Yonah’s 12. [Source]
The benchmarks in our performance comparison between Core Duo T2400 and Core 2 Duo T5600 showed results ranging from -0.3% to 34% (on average about 10%) improvement with the newer architecture. Energy consumption rose significantly however, which might be caused by the early Bios.
Similarly, the Core 2 Duo processor outperforms the AMD Turion 64 X2 at the same clock rate in virtually all applications (on average by 15%). The energy consumption is similar in both processors.
But what does that tell us about the Pentium Dual Core performance ?
There’s little in the way of available test results between the AMD Turion 64 X2 and the Pentium Dual Core. Your head will spin from the conflicting arguments given on the various internet forums on this subject. Understandable given each person has their own viewpoint, and there’s actually not a lot in it.
We can refer to our own processor performance benchmarking, which shows that the AMD Turion 64 X2 just shades the Pentium Dual Core processor. It does, though, depend a lot on which specific processors are compared. Generally, the AMD Turion 64 X2 just beats the Core 2 Duo based processors, while the difference is greater still with the Core Duo based processors.
But why should that be when we know that the Core 2 Duo processor generally out-performs the AMD 64 X2 in a head-to-head ?
The reason seems to lie in the size of the L2 Cache and the reduced clock speed of the Pentium Dual Core processors. Their L2 cache of 1MB appears to be below the sweet spot, anecdotally rather than from any clear test results, of somewhere between 2-3MB. This obviously has to be weighed up against price, Intel is targeting the Pentium Dual Core at the lower market end, and there is some very reasonably priced Pentium Dual Cores available. Go to our performance benchmarking page for results for specific processors.

Key Features - Core Duo vs Core 2 Duo

The table below shows the key features of the two sources for the Pentium Dual Core brand side-by-side. An accompanying notes section describes some of the key features, and also indicates where the architecture has been modified specifically for the Pentium Dual Core.
Feature based on Core Duo (Yonah) based on Core 2 Duo (Merom)
Manufacturing Process 65nm 65nm
Die Size 90.3 mm^2 144.9 mm^2
Transistors 151M 291M
Clock Speeds 1.20 - 2.33GHz 1.06 - 2.4GHz+
FSB Frequency 533MHz(Note 1) 533MHz
L1 Cache Size 32 + 32KB 32 + 32KB
L2 Cache Size 1MB Shared 1MB Shared(Note 2)
Pipeline Stages 12 14
Cores 2 2
Execute Disable Bit Yes Yes
Reorder Buffer 80 96
Wide Dynamic Execution No Every core can execute four complete commands simultaneously.
Smart Memory Access No Yes
Smart Cache Yes Yes, called Advanced Smart Cache with double the access bandwidth to the level 1 cache.
Advanced-Digital-Media-Boost No One 128-Bit SSE command is now output per clock cycle.
Virtualisation technology (VT) Partly? Partly?
64-bit operation No Yes
Enhanced Speedstep Technology Yes Yes
Advanced Thermal Manager Yes Yes
Streaming SIMD Extensions 3 (SSE3) Yes Yes
Dynamic Power Coordination Yes Yes
Macrofusion Yes Yes

Notes on the table

The FSB for the Pentium Dual Core executes at the lowest speed of the published frequency range for the Yonah,
The Pentium Dual Core uses only half the L2 cache available on the Yonah and Merom.
Execute Disable Bit
Prevents security problems through buffer overflows; if the operation system supports it and if activated.
Wide Dynamic Execution
Every core can execute four complete commands simultaneously. 
Smart-Memory-Access
Shorter idle times, improved data transfer and faster out-of-order command execution leading to better usage of the pipeline and resulting in a higher performance.
Advanced-Smart-Cache
Like the Core Duo, the Core 2 Duo has shared level 2 cache, but with double the access bandwidth to the level 1 cache.
Advanced-Digital-Media-Boost
One 128-Bit SSE command is now output per clock cycle.
Virtualisation technology (VT)
The Intel VT offers hardware support for virtual systems on one computer (use of several isolated operating systems at the same time e.g. through Xen or VMWare).
Enhanced Speedstep Technology
Introduced with the Pentium M and enables the processor to alter its clock frequency based on the computation needs at the time. It uses a voltage/clock configuration table to modify the frequency and voltage and hence power consumption on-the-fly. In addition, the Pentium M architecture includes separate power lines to different execution units allowing the autonomous disabling of idle execution units and data paths during the processing of an instruction.
Advanced Thermal Manager
Supports new digital temperature sensors and thermal monitors on each execution core to enhance thermal monitoring accuracy. This allows for more power efficiency savings over the Pentium M by the independent scaling of power between the two cores.
Streaming SIMD Extensions 3 (SSE3)
Additional 13 instructions designed to improve thread synchronization, complex arithmetic, graphics, and video encoding.
Dynamic Power Coordination
This feature cuts down the chipset's power consumption while the processor is running at reduced clock speeds by switching processor states between the Halt, Stop Clock, and Deep Sleep dynamically, and in the 2-core mode – synchronously to the Deeper and Enhanced Deeper Sleep modes. This distributed logic coordinates operation of the Enhanced Intel SpeedStep mode as well as switching between the C-states, which results in low supply voltage operation for Core Duo chips and minimum heat dissipation in the active state.
Macrofusion
A technique that “fuses” micro-ops derived from the same macro-op to reduce the number of micro-ops that need to be executed e.g. the fusion employed in the Core Duo and Core 2 Duo merges the compare and branch operations into a single operation.

The Desktop Market

Intel released their desktop equivalent Pentium Dual Core branded processors on June 3, 2007 with the Pentium E2140 and E2160, and subsequently the E2180 in September 2007. They are based on the Core 2 Duo Allendale core with 800MHz FSB, 1.6-2.0GHz clock speed, and using 65nm process technology. They resemble the Core 2 Duo E4300 processor with the exception of having 1 MB L2 cache instead of 2 MB.
On August 31st, 2008, Intel released the E5200 ‘Wolfdale’ under the Pentium Dual Core brand. Its stated working frequencies are higher than those of previous Core 2 Duo CPUs, and it is reckoned to be an excellent overclocker, while its thermal performance doesn’t seem to have been compromised by the smaller core and higher transistor density. Wolfdale is basically a dual-core desktop Penryn core with a 6MB L2 cache shared between the two cores using 45nm process technology, which provides for a smaller core over previous processors in the Core 2 Duo series. Just like all Pentium Dual Cores, only part of its L2 cache is enabled, but nonetheless, its 2MB L2 cache is larger than the other processors currently in the series.
Discussion

Models

TDP denotes Thermal Dissipation Power. The energy consumption of the processors is shown in the letter in front of the model code:
  • E-TDP over 50W (the Pentium Dual Core desktop processors start with 'E')
  • T-TDP about 24-49 W
  • L-TDP about 15-24W
  • U-TDP below 14W
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