If you have ever looked inside a computer you may have seen what looked like a scene from a science fiction movie; wires and chips and little flashing lights. What you are looking at is usually called the motherboard or main board, and all the hardware or physical parts of the computer communicate with each other through the motherboard. Information traveling to and from the CPU and other computer components travels along groups of wires in the motherboard called buses.
One of the most important components in a computer is the CPU (Central Processing Unit) or processor. Intel Pentium 4 and AMD Athlon are examples of processor lines. The CPU controls all of the components within the computer and performs all necessary calculations, kind of like your brain does for you. When a user selects a file to be printed, for example, it controls everything inside the computer that is needed for the file to be printed, i.e., sending the document in a word processing program to the printer.
RAM stands for Random Access Memory and influences how fast the computer runs. RAM is often referred to as main memory, primary memory, or just memory. This is because the CPU uses this memory first to complete all its tasks. Secondary memory is a permanent storage device, usually a disk. RAM acts as a temporary storage location for files, programs and other electronic data that are currently being used. RAM is electronic memory so it is very fast. Opening several programs and files at one time can slow down a computer because it begins to run out of RAM. A computer with more RAM allows more files to be open without slowing it down. Most computers nowadays have from 512 Megs of RAM to 2 Gigs of RAM and can also be upgraded to have more RAM.
Because accessing hard disks is very slow (usually measured in milliseconds), RAM (usually measured in nanoseconds) is used to hold data that is currently being worked on. When a Microsoft Word Document is opened and prepared to be edited, the application components needed to run Microsoft Word are first loaded into RAM by the Operating System. This means those components can be used immediately without being loaded from a disk each time they are used. Additionally, the data file to be edited or viewed is loaded into RAM. As the file is changed, the changes are saved in RAM so the user can see the changes as they are made. The original file still is on the disk. If each change was written to the disk as it was made, the computer would not be able to keep up with the changes. Disks are just too slow.
Think about how long it takes when you hit the save button on your document; it is only a second or two, but think about how slow it would be to type if you had to wait a second or two each time you hit a key or moved your mouse.
The only disadvantage of RAM is that when the power on the computer is stopped, RAM is lost because it is "volatile." It is powered by electricity, and when there is no more electricity, RAM is emptied or cleared. When a file is saved, the CPU takes what is in RAM and saves it to a disk which is a more permanent form of storage that can survive the power being turned off.
When you see discount specials in the Sunday newspaper for a $299 computer, chances are they’re selling you only 256 MB of RAM and a 2 GHz processor. Don’t be fooled into buying a low-end machine with a CRT monitor that won’t do what you need. For basic computing tasks, such a machine will be adequate, but you should really look at what software you will be running to determine whether it will be powerful enough. If you're working with large multimedia files or databases, the computer will need enough RAM to load the files into memory, otherwise the system will run slowly, because it has to keep reading from and writing to the hard drive. It doesn’t make sense, however, to purchase a high-end machine for over $2,000 that will only be used for surfing the web and occasionally composing a few text documents.