Lesson 4: How Computers Store Information
When you are talking to someone on the phone, the person on the other end hears what you are saying, but then your words are gone. The words from your conversation aren’t stored on the phone. However, leaving a voicemail is different than having a live conversation. The voicemail system answers the phone and records and stores the information given by the caller.
To process information, computers need to be able to store it. Otherwise, like the phone, information would come and go before anything could be done with it.
Computers store all kinds of information. They store the information you give them and instructions from the software you’re using, plus the instructions they need to operate.
Computers use two basic kinds of storage to hold all of this information. Temporary storage is for new information that is actively being used for processing, known as random access memory (RAM). Long-term storage is for information that computers use again and again, such as the instructions the computer uses every time you turn it on. These instructions are stored in read only memory (ROM), a type of memory that does not accept new information.
Computers also use a variety of devices to store information that isn’t actively being used for processing. For more information, explore hard drives, optical discs, and removable media in the site glossary.
Computers Need to Remember, Too
When someone asks you to add two numbers together, you rely on your memory to remember the rules of addition. Computers also rely on memory to remember the rules for certain activities. Computer programs include the instructions, or rules, for different types of tasks. In this addition example, a computer would need a math program in its RAM to “remember” how to calculate the result from adding numbers together.
However, some things come automatically to humans. When you breathe or move your arm, you do so without having to remember how your muscles work. Computers have this kind of built-in memory too—ROM, which remembers only what it was programmed to remember at the time the ROM chip was manufactured (like how to turn on or off). Remember, information stored in ROM is “read only,” meaning it can never be told to do something different after it has left the factory. That would be like trying to reprogram your body to breathe water instead of air.
Different Kinds of Storage Media
Computers use RAM for the information they currently need to do a task. Parts of the program and data you are currently using are held in RAM while you are working with them. But what about the rest of the programs and information on your computer? They are stored in a variety of other media. You are probably familiar with many of the ones shown on this page. What you might not know is the amazing amount of information some of these computers can hold.