Daily Archives: May 6, 2024

What is a CPU?

We use computers every day, and most users are aware of the one indispensable hardware component in it—the CPU or the Central Processing Unit. However, contrary to popular belief, the entire desktop computer or the router is not the CPU, as the actual CPU is small enough to fit in the palm of your hand. Small as it is, the CPU is the most important component inside any computer.

That is because the central processing unit is the main driving force or the brain of the computer and is the only component that does the actual thinking and decision-making. To do that, CPUs typically contain one or more cores that break up the workload and handle individual tasks. As each task requires data handling, a CPU must have access to the memory where such data actually resides. To enable fast computing, the memory speed must be high. This is generally RAM or Random Access Memory, and together with a great amount of cache memory, which is part of the CPU, helps the central processing unit to complete tasks at high speed. However, the RAM and cache can only store a small amount of data, and the CPU must periodically transfer the required data from external disk drives, as these can hold much more of it.

Being processors, CPUs are available in large varieties of ISAs or Instruction-Set Architectures. ISAs can be highly distinct, making them so extreme that software running on one ISA may not run on others. Even within CPUs using the same ISA, there may be differences in microarchitecture, specifically related to the actual design of the CPU. Manufacturers use different microarchitectures to offer CPUs with various levels of performance, features, and efficiency.

A CPU with a single core is highly efficient in accomplishing tasks that require a serial, sequential order of execution. To improve the performance even further, CPUs with multiple cores are available. Where consumer chips typically offer up to eight cores, bigger server CPUs may offer anywhere from 32 to 128 cores. CPU designers target improving per-core performance by increasing the clock speed, thereby increasing the number of instructions per second that the core handles. This is again dependent on the microarchitecture.

Crafting CPUs is an incredibly intricate endeavor, navigated by only a select few experts worldwide. Noteworthy contributors to this field include industry giants like Intel, AMD, ARM, and RISC-V International. Intel and AMD, the pioneers in this arena, consistently engage in fierce competition, each striving to outdo the other in various CPU categories.

ARM, on the other hand, distinguishes itself by offering its proprietary ARM ISA, a technology it licenses to prominent entities such as Apple, Qualcomm, and Samsung. These licensees then leverage the ARM ISA to fashion bespoke CPUs, often surpassing the performance of the standard ARM cores developed by the parent company.

In a departure from the proprietary norm, RISC-V International promotes an open-standard approach with its RISC-V ISA. This innovative model allows anyone to freely adopt and modify the ISA, fostering a collaborative environment that encourages diverse contributions to CPU design.

To truly grasp how well a CPU performs, your best bet is to dive into reviews penned by fellow users and stack their experiences against your specific needs. This usually involves delving into numerous graphs and navigating through tables brimming with numbers. Simply relying on the CPU specification sheet frequently falls short of providing a comprehensive understanding.