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What is a CPU (Central Processing Unit)?
A CPU (central processing unit) is the processor in a computer that orchestrates the flow of data and coordinates instructions between different computer components. The CPU ensures all calculations are performed in the correct sequence and makes certain that results are saved appropriately so they can be immediately reused or accessed later on when needed.
A CPU may also be referred to as a processor because, in the past, the CPU’s job was just to perform calculations. Today, most CPUs are microprocessors, which are chips that contain all the components needed to perform processing tasks. While this type of CPU does perform some calculations, its main job is to manage the other computer components, including the graphics processing unit (GPU), and coordinate task completion.
Some microprocessors contain other components like memory controllers and input/output interfaces, as well as core CPU elements. This type of CPU may also be referred to as a system on a chip (SoC). SoCs are commonly used in mobile devices, embedded systems, and other compact computing environments where integrating multiple functions into one chip improves efficiency while reducing space and power consumption.
Key Takeaways
- In the past, the CPU used to be the primary processor in a computer.
- Today, the CPU still performs some calculations, but its main job is to manage the way data flows and coordinate task completion.
- CPUs may also be referred to as processors, microprocessors, or SoCs.
- Key components of a CPU include an arithmetic logic unit (ALU), a control unit (CU), and registers.
- CPUs generate heat during operation, so computers use fans and heat sinks to prevent overheating.
CPU History
In 1971, Intel introduced the first CPU whose CPU parts were integrated on a single chip. Throughout the 1980s and 1990s, CPU development advanced rapidly, and by the mid-2000s, multicore processors became standard.
Multicore CPUs integrate multiple, fully functional CPUs on one chip. Each CPU (which is called a “core” in this context) can operate independently but still communicate with the other cores and share data. This change in chip architecture, which enabled parallel processing, helped increase energy efficiency as well as performance.
How Central Processing Units Work
A CPU carries out instructions from computer programs by performing a series of steps known as the instruction cycle or fetch-decode-execute cycle.
- First, the CPU fetches an instruction from the computer’s memory and decodes it to understand what needs to be done.
- Then, the CPU executes the instruction by carrying out the necessary operations.
- Once the task is completed, the CPU will either store the result in a register or in the computer’s main memory, depending on the operation and the program’s requirements.
CPU Core Components
A CPU’s core components are an arithmetic logic unit (ALU), a control unit (CU), and registers.
- Arithmetic logic unit (ALU): Performs arithmetic operations (addition, subtraction, multiplication, division) and logical operations (comparisons, bitwise operations) on data.
- Control unit (CU): Fetches instructions from memory, decodes them, and then signals the ALU and other components to execute the instructions.
- Registers: Small, high-speed storage locations within the CPU that hold the data and instructions that are currently being processed.
CPU Key Features
In addition to cores, the other key features of a CPU include:
Indicates how many cycles per second the CPU can execute. Each cycle represents a basic operation the CPU can perform.
Commands that a CPU can understand and execute. X86 instructions are commonly used for PC, and Advanced RISC Machine (ARM) instructions are commonly used for mobile devices.
Indicates the maximum amount of heat a CPU will generate for typical workloads.
Built-in graphics processing units that facilitate processing-intensive artificial intelligence (AI) and machine learning (ML) operations.
CPU Types
CPUs can be categorized by their architecture, intended use, and CPU performance capabilities.
Central Processing Units in Data Centers: Pros and Cons
CPUs perform important work, but they come with trade-offs in terms of the power they consume and the heat they create. These issues are amplified in large data centers.
For example, a data center for a popular web hosting provider may have millions of CPUs, and the heat they generate will require multiple types of cooling systems, most of which will consume additional power.
Pros
- CPUs provide the necessary processing capabilities to handle complex tasks and large volumes of data: they are essential for running cloud services, databases, and other critical applications
- CPUs can handle a wide range of workloads, from general-purpose computing to specialized tasks
- Data centers can scale their CPU resources by adding more servers to meet growing demand
Cons
- CPUs consume significant amounts of power, which can result in high operational costs
- A large number of CPUs in an enclosed space will generate substantial heat and require sophisticated cooling systems that also consume power and increase operational complexity
- Scaling out CPU resources requires more infrastructure, and this will increase the physical footprint of the data center
The Bottom Line
While CPU definitions have evolved over the years to include new types of CPUs, the core functions of a CPU have remained the same: fetch, decode, and execute instructions.
This instruction cycle is fundamental to how all CPUs operate, regardless of advancements in technology or the introduction of new types of CPUs.
