What's Smaller Than A Fingernail But Powers Everything From Your Phone To Mars Rovers? The Humble CPU—Here's Its Incredible Journey
- Igor Krivokapic
- Apr 1
- 6 min read
Updated: Apr 2
Understand the role of the Central Processing Unit (CPU) and how it works alongside other processors in your smartphone or PC. The CPU (Central Processing Unit) is a chip responsible for data processing in computers, smartphones, and other electronic devices, acting as the "brain" of these machines. Below, learn the difference between the CPU and different types of processors, how it works, its history, and its applications.
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History of the CPU
The CPU's journey from room-sized calculating machines to today's nanometer-scale processors represents one of technology's most remarkable evolutions. Meanwhile, the Intel 4004 (1971) marked the first commercial single-chip CPU. The transition from discrete transistors to integrated circuits in the late 1950s made microprocessors possible, setting the stage for the computing revolution.
This evolution accelerated dramatically with Moore's Law, which observed that transistor counts doubled every two years. From the 4-bit 4004 (2,300 transistors) to modern 64-bit chips like Apple's M2 (20 billion transistors), CPUs have become exponentially more potent while shrinking to microscopic sizes. Key milestones include the first x86 architecture (Intel 8086, 1978), multi-core designs (2000s), and today's heterogeneous processors combining different core types for optimal performance and efficiency.
What began as specialized hardware for calculators now powers everything from smartwatches to supercomputers. CPU architectures are adapting to new demands like AI processing and quantum computing challenges on the horizon. This continuous innovation ensures the CPU remains the "brain" of modern computing, just as essential today as when the first microprocessors appeared over 50 years ago.
What are the components of a CPU?
The Central Processing Unit (CPU) is divided into three essential units: the Control Unit (CU), the Arithmetic Logic Unit (ALU), and the Registers. Below, learn more about the function of each.
What is the CPU's control unit (CU)?
The Control Unit is a circuit that generates electrical signals to organize how and when instructions should be executed. These signals direct communication between the CPU and components such as RAM and input/output devices.
The Control Unit's operation depends on the processor's architecture and sophistication. However, in all cases, the component follows the routine of fetching instructions from memory, interpreting them, and directing them at the appropriate time for execution.
What is the purpose of the Arithmetic Logic Unit (ALU) in the CPU?
The Arithmetic Logic Unit (ALU) is a circuit that executes logical operations, calculations like addition and multiplication, and complex Boolean operations (based on the binary system).
These operations are essential for the CPU to perform calculations and comparisons that lead to data processing according to the instructions directed by the Control Unit. Therefore, the ALU is considered a crucial element in all CPUs.
What are the registers in a CPU?
Registers are fast, volatile memory (losing data when power is lost) used in small amounts for data storage. Their function is to allow the CPU immediate access to data and instructions needed for executing logical or arithmetic operations.
Registers typically provide the fastest data access for the CPU. Without them, operations could take longer, underutilizing the CPU's processing capability.
What is the purpose of the CPU cache?
Cache is a type of temporary memory that allows the CPU to access data and process it faster than if it were retrieved solely from RAM. The processor cache is divided into levels. The lower the level, the faster (but also more expensive) the memory.
What are CPU instruction cycles?
An instruction cycle is the period the CPU takes to fetch instructions from memory and execute them, which is why this process is also known as the "fetch-execute cycle." Instructions can be executed in an overlapping manner, a technique called pipelining.
Instruction cycles vary depending on processor architecture or CPU specifications. However, there are basic stages in all cases:
Fetch: The instruction is retrieved based on the memory address where it is stored and placed in a register.
Decode: The fetched instruction is interpreted, breaking it down into arithmetic or logical operators and operands (entities like constants or variable values).
Operand Fetch: The memory addresses of the operands are calculated, and then they are retrieved.
Execute: The control unit decodes the data and directs it to components like the ALU to execute the operation.
Store: The operation's result is stored in the main memory. Then, a new cycle begins.
What are CPU cores?
A processor core is a complete execution unit. Each core contains a Control Unit, an Arithmetic Logic Unit, and registers. There may also be dedicated cache memory, though some cache levels may be shared depending on the chip's architecture.
A CPU may have a single core (where the core is the CPU itself) or be multi-core, meaning it has two or more cores. Generally, the more cores, the greater the processing capability. High-end models for servers and professional applications can have over 100 cores.
One way to determine the number of CPU cores is to search for the entire chip name on Google or Bing. Usually, the first results lead to the product's official page, which lists the number of cores and other specifications.
Another option is to use apps like CPU-Z, which are available for Windows and Android. The software reveals the number of CPU cores and details like cache size, clock speed, and all hardware on your motherboard.
Is an octa-core processor better than a quad-core?
An octa-core smartphone (eight cores) will only outperform a quad-core model (four cores) if its overall features make it more potent than the second device.
The number of CPU cores is not a good performance indicator on its own. Other factors must be considered, such as each core's clock speed, cache size, and chip fabrication technology.
What determines CPU speed?
Beyond the number of cores and features like cache, the processor's clock speed (frequency) is critical for performance. This parameter indicates the number of operation cycles per second the CPU executes.
Clock speed is measured in hertz (Hz), where 1 Hz equals one operation cycle per second. Modern CPUs operate in gigahertz (GHz). 1 GHz equals 1,000,000,000 Hz, so a 1.8 GHz chip executes up to 1.8 billion cycles per second.
What is CPU overclocking?
Overclocking is a procedure for increasing the CPU's frequency beyond the manufacturer's defined limit. A higher clock speed improves performance since more cycles are executed per second. However, if done carelessly, overclocking can damage the CPU or cause malfunctions.
What is the ideal CPU temperature?
The ideal CPU temperature depends on usage, but generally, it should stay below 50°C during idle times. Under full load, the temperature should not exceed 80°C.
Monitoring PC temperature regularly helps avoid crashes or slowdowns caused by thermal throttling, a mechanism that limits chip performance to prevent overheating.
Knowing a processor's Thermal Design Power (TDP) helps choose a cooling solution that keeps the CPU within recommended levels.
Why does CPU usage reach 100%?
If the computer shows a 100% CPU usage notification or this appears in monitoring software like Windows Task Manager, it means the processor is running at maximum capacity. This usually causes system slowdowns.
100% CPU usage can result from running software that demands more hardware resources than the computer provides. Other reasons include malware or malfunctioning software monopolizing processing cores.
Ending problematic processes and restarting the computer are ways to reduce CPU usage.
What does the CPU do in games?
The CPU handles graphics-related tasks during gameplay, such as mathematical calculations for gameplay mechanics, physics, and difficulty levels. Meanwhile, the GPU handles graphical processing, rendering textures, 3D objects, shadows, and other visual elements.
It is essential that both the CPU and GPU are cutting-edge if you want your gaming to be as smooth as possible. Pairing a powerful GPU with a weak CPU (or vice versa) can hurt game performance.
How is the CPU used in parallel computing?
Parallel processing allows a computer to perform multiple operations simultaneously. This concept can be used for complex calculations, breaking problems into smaller tasks executed in parallel.
Parallel computing can involve multiple processors or, in a single computer, utilize all CPU cores.
What is the difference between CPU, processor, and case?
The CPU is a silicon chip that executes processes—sequences of instructions and data corresponding to software. This is why the CPU is also commonly called a processor.
However, computers and mobile devices have other processors, such as the Image Signal Processor (ISP), which converts camera sensor data into photos, and the GPU in a graphics card, which processes graphical data.
Some use "CPU" to refer to the computer case, but they are different. The CPU is solely a chip installed on the motherboard. The case is the "box" housing all computer components, also called a desktop or tower.
In Conclusion
From the bulky vacuum tubes of early computers to today's multi-core, AI-accelerated processors, the CPU has remained the beating heart of computing. Its evolution—driven by relentless innovation—has powered every digital revolution, from personal computers to smartphones and beyond. As we look toward quantum and neuromorphic computing, one thing is certain: the CPU's legacy as the "brain" of technology will continue to shape our future.
What's next for processor technology? The next chapter in computing is already being written.
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