Computer Basics by Librarian Nicholas Saturno

Computer Basics

Central Processing Unit CPU: also called a central processor, main processor or just processor, is the electronic circuitry within a computer that executes instructions that make up a computer program. The CPU performs basic arithmetic, logic, controlling, and input/output (I/O) operations specified by the instructions in the program.

Random-access memory RAM: is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code.

Internal Cache (also called primary or L1 cache), when the computer needs data it first looks in the internal cache. The internal cache is inside the CPU and is the fastest possible way for the computer to get information. The internal cache can normally only contain a very small amount of information.

External Cache (also called secondary or L2 cache), if the computer doesn’t find the data in the internal cache, it then looks in the external cache. The external cache is slower than the internal cache, but much faster than the normal RAM memory. The external cache normally holds much more information than the internal cache, but still not as much as the main memory (RAM).

If the computer can’t find what it needs in the internal or external cache, it looks in the slower main memory (RAM), if the computer still can’t find what it needs, it looks at the slow as molasses hard disk cache.

Hard disk drive HDD: is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage and one or more rigid rapidly rotating platters coated with magnetic material.

A hard drive’s average access time is how fast it can find information. Average access time is measured in milliseconds (ms), or 1/1000 of a second. The lower the access speed, the faster the hard drive. Most newer computers have an average access time of 8 to 15 ms. Another factor that determines hard drive performance is how fast it spins, in revolutions per minute (rpms). Faster IDE hard drives may have speeds as fast as 7,200 rpm, while high-end SCSI hard drives have speeds of 15,000 rpm.

Not only do you need a fast hard drive, but you must also make sure that is has plenty of free storage space. Microsoft Windows uses this hard disk space to create a cache on the hard drive where it stores temporary information

Normally a computer stores a file in the same location on a hard drive. Over time, a hard drive can become fragmented, and instead of storing a file in the same location it begins storing parts of it all over. When the computer needs to read a fragmented file, it must read several different parts of the hard drive instead of just one. Defragmenting a hard drive puts the fragmented files back together in one place. You should defragment your computer’s hard drive about once a month.

Now that you understand the basics, you can purchase a computer with some knowledge in hand. Instead of listening to a nerdy computer salesperson, who may be on commission or a sales quota, you now know the basics of computer infrastructure to ask intelligent questions when buying a computer. For most home buyers they are middle of the road. Users will need to work with emails, word processing, and browsing the Internet. For these functionalities you do not need a high-end computer that will cost you over $2,000. Today you can purchase a computer in the $300 to $700 range to preforms basic functions mentioned before. I always recommend with the Intel chip for CPU. Chip is more powerful and faster that a Celeron chip. Of course, the faster the CPU in GHz you will pay more money. You can always go a notch or two below the top speed of chip. For email, word processing, and web browsing you do not need a gaming or high-end computer. A lower end model in the $300 range will suffice for your needs at home.

For those of you interested in a laptop, all the same computer specifications apply. The differences when purchasing a laptop is to look at the battery life, size of screen, warranty, included devices and features.