Computers are designed to reduce the complexity in our lives. However, if you are looking to upgrade your current PC or buy an entirely new system, the terminology can quickly become confusing, especially when it comes to the CPU – the heart of any computer system. This buying guide will walk you through everything you need to know to make an informed CPU purchase decision.
These days it’s not just about choosing a specific CPU at a specific price point. You need to consider the types of motherboards that a single CPU will work with, the additional features you’re looking for in a processor, and the types of software you’re likely to be running on your computer. It’s far better to make the right choice and buy a PC that’s ideal for your chosen applications than to end up with something that sounds good on paper but can’t do the core tasks you need .
What is a CPU?
CPU stands for Central Processing Unit, and even after many years of refining PC technology, the CPU is still the heart of your computer’s operation. It controls the flow of data throughout your PC (hence the central part). The processing part is equally important, as the CPU’s role is to manipulate – or process – the data going through your computer, reading it from storage devices, modifying it as needed, and then putting it into memory or display to write devices.
At the physical level, a CPU consists of millions of microscopic transistors that are etched onto a layer of silicon through chemical and lithographic processes. Transistors themselves are exceptionally simple devices that store binary (on/off) values, and more complicated processes can be performed based on these on/off states. To give you an idea of the complexity of a modern transistor, a dual-core CPU like Intel’s Core 2 Duo E6700 consists of almost 291 million transistors. With a quad-core chip like Intel’s Core 2 Extreme QX6850, that transistor count increases to around 582 million.
To perform any useful data task, a CPU requires a few basic components. While the exact details of how each processor does this vary quite a bit depending on the architecture of each model, the basics remain the same. A CPU must be able to receive data, transform it in a meaningful way based on the instructions given to it, and then send that data to an appropriate repository. The repository can be a storage medium like a hard drive, a visual display like a monitor, or even the CPU itself for further computation.
At the simplest level, the CPU only needs four elements to perform its data operations: instructions, an instruction pointer, some registers, and the arithmetic and logic unit.
The instruction pointer tells the CPU where in memory is the instruction it needs to execute.
Registers are temporary storage locations on the CPU. A register contains data waiting to be processed by an instruction or data that has already been processed (e.g. the result of adding two numbers).
The arithmetic logic unit, or ALU, acts as the processor of the CPU, performing the math and logic functions dictated by the instructions.
Besides these core elements, the CPU has some additional parts that help these core elements to do their job:
- Instruction fetch grabs instructions from RAM or an area of memory located on the CPU;
- The instruction decoder takes the instruction off the fetch and translates it in a way that the CPU understands. It then determines what steps are necessary to execute that statement;
- The control unit manages and coordinates all operations of the chip. It tells the ALU when to compute, tells the fetch when to fetch a value, and tells the decoder when to translate the value into an instruction.
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