Types of central processing units (CPUs)

What is a CPU?

The central processing unit (CPU) is the computer’s brain. It handles the assignment and processing of tasks and manages operational functions that all types of computers use.

CPU types are designated according to the kind of chip that they use for processing data. There’s a wide variety of processors and microprocessors available, with new powerhouse processors always in development. The processing power CPUs provide enables computers to engage in multitasking activities. Before discussing the types of CPUs available, we should clarify some basic terms that are essential to our understanding of CPU types.

Key CPU terms

There are numerous components within a CPU, but these aspects are especially critical to CPU operation and our understanding of how they operate:

• Cache: When it comes to information retrieval, memory caches are indispensable. Caches are storage areas whose location allows users to quickly access data that’s been in recent use. Caches store data in areas of memory built into a CPU’s processor chip to reach data retrieval speeds even faster than random access memory (RAM) can achieve. Caches can be created through software development or hardware components.

• Clock speed: All computers are equipped with an internal clock, which regulates the speed and frequency of computer operations. The clock manages the CPU’s circuitry through the transmittal of electrical pulses. The delivery rate of those pulses is termed clock speed, which is measured in Hertz (Hz) or megahertz (MHz). Traditionally, one way to increase processing speed has been to set the clock to run faster than normal.

• Core: Cores act as the processor within the processor. Cores are processing units that read and carry out various program instructions. Processors are classified according to how many cores are embedded into them. CPUs with multiple cores can process instructions considerably faster than single-core processors. (Note: The term “Intel® Core™” is used commercially to market Intel’s product line of multi-core CPUs.)

• Threads: Threads are the shortest sequences of programmable instructions that an operating system’s scheduler can independently administer and send to the CPU for processing. Through multithreading—the use of multiple threads running simultaneously—a computer process can be run concurrently. Hyper-threading refers to Intel’s proprietary form of multithreading for the parallelization of computations.

Other components of the CPU

In addition to the above components, modern CPUs typically contain the following:

• Arithmetic logic unit (ALU): Carries out all arithmetic operations and logical operations, including math equations and logic-based comparisons. Both types are tied to specific computer actions.
• Buses: Ensures proper data transfer and data flow between components of a computer system.
• Control unit: Contains intensive circuitry that controls the computer system by issuing a system of electrical pulses and instructs the system to carry out high-level computer instructions.
• Instruction register and pointer: Displays location of the next instruction set to be executed by the CPU.
• Memory unit: Manages memory usage and the flow of data between RAM and the CPU. Also, the memory unit supervises the handling of cache memory.
• Registers: Provides built-in permanent memory for constant, repeated data needs that must be handled regularly and immediately.

How do CPUs work?

CPUs use a type of repeated command cycle that’s administered by the control unit in association with the computer clock, which provides synchronization assistance.

The work a CPU does occurs according to an established cycle (called the CPU instruction cycle). The CPU instruction cycle designates a certain number of repetitions, and this is the number of times the basic computing instructions will be repeated, as enabled by that computer’s processing power.

The three basic computing instructions are as follows:

• Fetch: Fetches occur anytime data is retrieved from memory.
• Decode: The decoder within the CPU translates binary instructions into electrical signals, which engage with other parts of the CPU.
• Execute: Execution occurs when computers interpret and carry out a computer program’s set of instructions.

Basic attempts to generate faster processing speeds have led some computer owners to forego the usual steps involved in creating high-speed performance, which normally require the application of more memory cores. Instead, these users adjust the computer clock so it runs faster on their machine(s). The “overclocking” process is analogous to “jailbreaking” smartphones so their performance can be altered. Unfortunately, like jailbreaking a smartphone, such tinkering is potentially harmful to the device and is roundly disapproved by computer manufacturers.

Types of central processing units

CPUs are defined by the processor or microprocessor driving them:

• Single-core processor: A single-core processor is a microprocessor with one CPU on its die (the silicon-based material to which chips and microchips are attached). Single-core processors typically run slower than multi-core processors, operate on a single thread and perform the instruction cycle sequence only once at a time. They are best suited to general-purpose computing.
• Multi-core processor: A multi-core processor is split into two or more sections of activity, with each core carrying out instructions as if they were completely distinct computers, although the sections are technically located together on a single chip. For many computer programs, a multi-core processor provides superior, high-performance output.
• Embedded processor: An embedded processor is a microprocessor expressly engineered for use in embedded systems. Embedded systems are small and designed to consume less power and be contained within the processor for immediate access to data. Embedded processors include microprocessors and microcontrollers.
• Dual-core processor: A dual-core processor is a multi-core processor containing two microprocessors that act independently from each other.
• Quad-core processor: A quad-core processor is a multi-core processor that has four microprocessors functioning independently.
• Octa-core: An octa-core processor is a multi-core processor that has eight microprocessors functioning independently.
• Deca-core processor: A deca-core processor is an integrated circuit that has 10 cores on one die or per package.

Leading CPU manufacturers and the CPUs they make

Although several companies manufacture products or develop software that supports CPUs, that number has dwindled down to just a few major players in recent years.

The two major companies in this area are Intel and Advanced Micro Devices (AMD). Each uses a different type of instruction set architecture (ISA). Intel processors use a complex instruction set computer (CISC) architecture. AMD processors follow a reduced instruction set computer (RISC) architecture.

• Intel: Intel markets processors and microprocessors through four product lines. Its premium, high-end line is Intel Core. Intel’s Xeon® processors are targeted toward offices and businesses. Intel’s Celeron® and Intel Pentium® lines are considered slower and less powerful than the Core line.

• Advanced Micro Devices (AMD): AMD sells processors and microprocessors through two product types: CPUs and APUs (which stands for accelerated processing units). APUs are CPUs that have been equipped with proprietary Radeon™ graphics. AMD’s Ryzen™ processors are high-speed, high-performance microprocessors intended for the video game market. Athlon™ processors was formerly considered AMD’s high-end line, but AMD now uses it as a basic computing alternative.

• Arm: Although Arm doesn’t actually manufacture equipment, it does lease out its valued, high-end processor designs and/or other proprietary technologies to other companies who do make equipment. Apple, for example, no longer uses Intel chips in Mac® CPUs but makes its own customized processors based on Arm designs. Other companies are following this example.

Related CPU and processor concepts

Graphics processing unit (GPUs)

While the term “graphics processing unit” includes the word “graphics,” this phrasing does not truly capture what GPUs are about, which is speed. In this instance, its increased speed is the cause of accelerating computer graphics.

The GPU is a type of electronic circuit with immediate applications for PCs, smartphones and video game consoles, which was their original use. Now GPUs also serve purposes unrelated to graphics acceleration, like cryptocurrency mining and the training of neural networks.

Microprocessors

The quest for computer miniaturization continued when computer science created a CPU so small that it could be contained within a small integrated circuit chip, called the microprocessor. Microprocessors are designated by the number of cores they support.

A CPU core is “the brain within the brain,” serving as the physical processing unit within a CPU. Microprocessors can contain multiple processors. Meanwhile, a physical core is a CPU built right into a chip, but which only occupies one socket, thus enabling other physical cores to tap into the same computing environment.

Output devices

Computing would be a vastly limited activity without the presence of output devices to execute the CPU’s sets of instruction. Such devices include peripherals, which attach to the outside of a computer and vastly increase its functionality.

Peripherals provide the means for the computer user to interact with the computer and get it to process instructions according to the computer user’s wishes. They include desktop essentials like keyboards, mice, scanners and printers.

Peripherals are not the only attachments common to the modern computer. There are also input/output devices in wide use and they both receive information and transmit information, like video cameras and microphones.

Power consumption

Several issues are impacted by power consumption. One of them is the amount of heat produced by multi-core processors and how to dissipate excess heat from that device so the computer processor remains thermally protected. For this reason, hyperscale data centers (which house and use thousands of servers) are designed with extensive air-conditioning and cooling systems.

There are also questions of sustainability, even if we’re talking about a few computers instead of a few thousand. The more powerful the computer and its CPUs, the more energy will be required to support its operation—and in some macro-sized cases, that can mean gigahertz (GHz) of computing power.

Specialized chips

The most profound development in computing since its origins, artificial intelligence (AI) is now impacting most if not all computing environments. One development we’re seeing in the CPU space is the creation of specialty processors that have been built specifically to handle the large and complex workloads associated with AI (or other specialty purposes):

• Such equipment includes the Tensor Streaming Processor (TSP), which handles machine learning (ML) tasks in addition to AI applications. Other products equally suited to AI work are the AMD Ryzen Threadripper™ 3990X 64-Core processor and the Intel Core i9-13900KS Desktop Processor, which uses 24 cores.
• For an application like video editing, many users opt for the Intel Core i7 14700KF 20-Core, 28-thread CPU. Still others select the Ryzen 9 7900X, which is considered AMD’s best CPU for video editing purposes.
• In terms of video game processors, the AMD Ryzen 7 5800X3D features a 3D V-Cache technology that helps it elevate and accelerate game graphics.
• For general-purpose computing, such as running an OS like Windows or browsing multimedia websites, any recent-model AMD or Intel processor should easily handle routine tasks.

Transistors

Transistors are hugely important to electronics in general and to computing in particular. The term is a mix of “transfer resistance” and typically refers to a component made of semiconductors used to limit and/or control the amount of electrical current flowing through a circuit.

In computing, transistors are just as elemental. The transistor is the basic building unit behind the creation of all microchips. Transistors help comprise the CPU, and they’re what makes the binary language of 0s and 1s that computers use to interpret Boolean logic.

The next wave of CPUs

Computer scientists are always working to increase the output and functionality of CPUs. Here are some projections about future CPUs:

• New chip materials: The silicon chip has long been the mainstay of the computing industry and other electronics. The new wave of processors (link resides outside ibm.com) will take advantage of new chip materials that offer increased performance. These include carbon nanotubes (which display excellent thermal conductivity through carbon-based tubes approximately 100,000 times smaller than the width of a human hair), graphene (a substance that possesses outstanding thermal and electrical properties) and spintronic components (which rely on the study of the way electrons spin, and which could eventually produce a spinning transistor).
• Quantum over binary: Although current CPUs depend on the use of a binary language, quantum computing will eventually change that. Instead of binary language, quantum computing derives its core principles from quantum mechanics, a discipline that has revolutionized the study of physics. In quantum computing, binary digits (1s and 0s) can exist in multiple environments (instead of in two environments currently). And because this data will live in more than one location, fetches will become easier and faster. The upshot of this for the user will be a marked increase in computing speed and an overall boost in processing power.

• AI everywhere: As artificial intelligence continues to make its profound presence felt—both in the computing industry and in our daily lives—it will have a direct influence on CPU design. As the future unfolds, expect to see an increasing integration of AI functionality directly into computer hardware. When this happens, we’ll experience AI processing that’s significantly more efficient. Further, users will notice an increase in processing speed and devices that will be able to make decisions independently in real time. While we wait for that hardware implementation to occur, chip manufacturer Cerebras has already unveiled a processor its makers claim to be the “fastest AI chip in the world” (link resides outside ibm.com). Its WSE-3 chip can train AI models with as many as 24 trillion parameters. This mega-chip contains four trillion transistors, in addition to 900,000 cores.

CPUs that offer strength and flexibility

Companies expect a lot from the computers they invest in. In turn, those computers rely upon having a CPUs with enough processing power to handle the challenging workloads found in today’s data-intensive business environment.

Organizations need workable solutions that can change as they change. Smart computing depends upon having equipment that capably supports your mission, even as that work evolves. IBM servers offer strength and flexibility, so you can concentrate on the job at hand. Find the IBM servers you need to get the results your organization relies upon—both today and tomorrow.

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