Wednesday, October 10, 2012

What is Processor

The brain or engine of the PC is the processor—sometimes called microprocessor or central processing unit (CPU). The CPU performs the system’s calculating and processing. The processor is often the most expensive single component in the system; in higher-end systems it can cost up to four or more times more than the motherboard it plugs into. Intel is generally credited with creating the first microprocessor in 1971 with the introduction of a chip called the 4004. Today Intel still has control over the processor market, at least for PC systems, although AMD has garnered a respectable market share. For the most part, PC-compatible systems use either Intel processors or Intel-compatible processors from a handful of competitors such as AMD and VIA/Cyrix


The first major change in processor architecture was the move from the 16-bit internal architecture of the 286 and earlier processors to the 32-bit internal architecture of the 386 and later chips, which Intel calls IA-32 (Intel Architecture, 32-bit). Intel’s 32-bit architecture dates to 1985, and it took a full 10 years for both a partial 32-bit mainstre am OS (Windows 95) as well as a full 32-bit OS requiring 32-bit drivers (Windows NT) to surface, and another 6 years for the mainstream to shift to a fully 32-bit environment for the OS and drivers (Windows XP). That’s a total of 16 years from the release of 32-bit computing hardware to the full adoption of 32-bit computing in the mainstream with supporting software. I’m sure you can appreciate that 16 years is a lifetime in technology. Now we are in the midst of another major architectural jump, as Intel, AMD, and Microsoft are in the process of moving from 32-bit to 64-bit architectures. In 2001, Intel had introduced the IA-64 (Intel Architecture, 64-bit) in the form of the Itanium and Itanium 2 processors, but this standard was something completely new and not an extension of the existing 32-bit technology. IA-64 was first announced in 1994 as a CPU development project with Intel and HP (code-named Merced), and the first technical details were made available in October 1997. The fact that the IA-64 architecture is not an extension of IA-32 but is instead a whole new and completely different architecture is fine for non-PC environments such as servers (for which IA-64 was designed), but the PC market has always hinged on backward compatibility. Even though emulating IA-32 within IA-64 is possible, such emulation and support is slow.
With the door now open, AMD seized this opportunity to develop 64-bit extensions to IA-32, which it calls AMD64 (originally known as x86-64). Intel eventually released its own set of 64-bit extensions, which it calls EM64T or IA-32e mode. As it turns out, the Intel extensions are almost identical to the AMD extensions, meaning they are software compatible. It seems for the first time that Intel has unarguably followed AMD’s lead in the development of PC architecture. To make 64-bit computing a reality, 64-bit operating systems and 64-bit drivers are also needed. Microsoft began providing trial versions of Windows XP Professional x64 Edition (which supports AMD64 and EM64T) in April 2005, but it wasn’t until the release of Windows Vista x64 in 2007 that 64-bit computing would begin to go mainstream. Initially, the lack of 64-bit drivers was a problem, but by the release of Windows 7 x64 in 2009, most device manufacturers provide both 32-bit and 64-bit drivers for virtually all new devices. Linux is also available in 64-bit versions, making the move to 64-bit computing possible for non-Windows environments as well.
Another important development is the introduction of multicore processors from both Intel and AMD. Current multicore processors have up to four or more full CPU cores operating off of one CPU package—in essence enabling a single processor to perform the work of multiple processors. Although multicore processors don’t make games that use single execution threads play faster, multicore processors, like multiple single-core processors, split up the workload caused by running multiple applications at the same time. If you’ve ever tried to scan for malware while simultaneously checking email or running another application, you’ve probably seen how running multiple applications can bring even the fastest processor to its knees. With multicore processors available from both Intel and AMD, your ability to get more work done in less time by multitasking is greatly enhanced. Current multicore processors also support 64-bit extensions, enabling you to enjoy both multicore and 64-bit computing’s advantages.
PCs have certainly come a long way. The original 8088 processor used in the first PC contained 29,000 transistors and ran at 4.77MHz. Compare that to today’s chips: The AMD Phenom II has an estimated 758 million transistors and runs at up to 3.4GHz or faster, and the Intel Core i5/i7 have up to 774 million transistors and run at up to 3.33GHz or faster. As multicore processors with large integrated caches continue to be used in more and more designs, look for transistor counts and real-world performance to continue to increase well beyond a billion transistors. And the progress won’t stop there, because according to Moore’s Law, processing speed and transistor counts are doubling every 1.5–2 years.

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