Computer Memory and Processing Devices: Functions & Characteristics

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  • 0:05 Complex Computers
  • 0:17 Central Processing Unit
  • 0:57 Memory
  • 4:01 Lesson Summary
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Lesson Transcript
Instructor: Lori Jacobson

Lori holds an MBA. She has taught business and accounting at several community colleges.

Have you ever wondered how your computer operates - specifically, where it stores all the information it needs to run? This lesson will answer that question by explaining the general functions of the central processing unit (CPU), random-access memory (RAM) and read-only memory (ROM).

Complex Computers

Computers have many complex pieces. On the motherboard you will find many things, including the central processing unit, random-access memory and read-only memory. The most vital piece is the CPU.

The CPU analyzes every instruction we input and performs logarithmic calculations.
CPU Operation Flowchart

Central Processing Unit

The CPU is the brains of the computer. The central processing unit has to think through every instruction generated by your use of the computer. These instructions include having the arithmetic logic unit (ALU) performing the logarithmic calculations to interpret these instructions. The processing is done at a speed that is nearly impossible for our brains to comprehend, let alone actually perform.

The speeds are referred to with the term hertz (not the car rental, by the way). The speeds are actually in the millions (mega) or billions (giga) of machine cycles per second! Think of it as revolutions per minute in an engine but a heck of a lot faster!



The path of thinking includes volatile and non-volatile memory, or temporary and permanent memory, respectively. Random-access memory (RAM) is volatile, or temporary, memory. It wakes up when you turn on your computer and holds the information you are working on. Think of those different windows being open in the programs you're using; those sit in RAM when you're working on them. They're right there up front for easy access and processing.

The system bus sends and receives data.
System Bus Flowchart

An even more up-front memory is called the cache. It's simply another form of working memory. Because it is volatile, it will empty when the computer is shut off. The cache is located on or near the CPU. It holds instructions that are repetitive for program use. Because of its proximity to the CPU, the cache doesn't have to take the long way to work: the system bus. The bus is an electronic line that sends and receives data.

As soon as the machine is shut down, both RAM and the cache are cleared out. RAM is located in slots on the motherboard and is measured in storage capacity of megabytes (or just over 1 million bytes) or gigabytes (over 1 billion bytes). The more RAM that's installed on a computer, combined with a CPU that has a high processing speed, the stronger the computing power will be. For today's basic user and personal computer shopper, some RAM acronyms may be confusing. In-depth analyses of each are not necessary, but note the progression of today's technology.

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