Central Processing Unit (CPU)

The CPU can be thought of as the “brain” of the computer. A processor is designed to perform arithmetic and logic operations using built-in instructions for addition, subtraction, comparison, etc. Any more complicated actions, such as playing a game, are completed by the computer performing these operations at very high speeds. Processors are used to break each operation up into steps, like an assembly line, with an internal clock that tells the processor when to move to the next step in the calculation.

AMD Athlon 64 x2
AMD® Athlon 64 X2
Intel Pentium Core2 quad-core processor
Intel® Pentium Core2 quad-core processor

Video Processor

A video processor is a microprocessor, like the one that is running your computer, with more specific operations – focused on producing graphical output to a monitor. Video processors typically have dedicated memory on more expensive machines, and share the main RAM in less expensive ones. More intensive graphical applications, such as video games, will require that the video processor have more memory, or use more of the RAM.

Nvidia GeForce GTX 580 video card (desktop)
Nvidia GeForce GTX 580 Video Card (desktop)
Nvidia Mobile 6800 Ultra video card
Nvidia Mobile 6800 Ultra Video Card

Additional Information & Resources:


Processors come in a variety of designs and layouts. However, many times they are grouped into families that can run the same instruction sets. Instruction sets are the languages that the processors understand. The most common instruction set is x86 and is found in all new PCs. It includes processors from Intel (Core, Pentium, and Xeon), AMD (Athlon, Duron, and Opteron) and a few smaller companies. Apple computers used to use an instruction set called PowerPC with processors from Motorola (PowerPC G4) and IBM (PowerPC G5), and then they switched to the x86 instruction set as well (Intel processors). In 2020, Apple announced that Mac systems would transition to Apple silicon. There are other instruction sets out there but they are mainly used in servers, specialized workstations, and game consoles.

There has also been a rise of 64-bit processors over 32-bit processors. The biggest change between these two architectures is that a 64-bit processor has integer and addressing registers (memory locations) that are 64-bits wide rather than 32-bits. A 32-bit processor can address up to 232 data registers, and a 64-bit processor can address up to 264.


Processors used to be advertised almost exclusively by their clock speed, measured in GHz (gigahertz). As their architectures began to differ more and more, both AMD and Intel moved to using processor model numbers. In addition to clock speed, processor vendors sell based on varying amounts of cache (small but very fast memory) and thermal rating, among other things. The thermal rating is how much heat the processor generates while it is running. This is usually the main differentiator between desktop and laptop processors, with laptops requiring cooler-running processors.

Most multi-core processors are dual-core; however, there are now processors available with up to 6 cores. What this means is that they have effectively put two (or more) processors inside of one. An important thing to remember is that most of the software out there has not been written to use more than one processor. While having two processors may make the computer faster when using multiple applications, it will not speed up a single application.


Processors also implement a technology called hyper-threading. This is a method of computing multiple tasks at once. To do this, the operating system addresses two virtual processors for each core of the processor that is present in the hardware, and tasks are then shared between the two virtual processors.

With regards to multi-core processors, it is important to understand that a single core processor cannot multi-task. When using a computer, it may not appear this way, however, the CPU’s core only executes one task at a time. This is managed efficiently, however, through CPU scheduling which ‘schedules’ the tasks in a manner that the computer can get the most done in the least amount of time. So, when you are listening to music, talking on instant messenger, and surfing the internet, you may appear to be multi-tasking, but the computer is not. However, this is not the case with multi-core processors, as each core can execute a separate task. As mentioned before, this is why multi-core processors are capable of running multiple programs faster but not a single program faster unless it was specifically written for a multi-core processor.

How Processors Work:

Intel and AMD processor architectures: