Inside a computer is a “hard disk”, which is able to store information (data) even when the machine is turned off. There are also two other kinds of storage in a computer. ROM (read-only memory) stores the instructions that tell the computer how to start working when it is first switched on. RAM (random-access memory) stores data that is in use. To make sure that data is permanently stored, it must be “saved” on the hard disk before the computer is switched off.
At the core of the computer is the central processing unit or CPU, the source of control that runs all programs and instructions. In order to function, computers use two types of memory: primary and secondary. The main storage is the primary memory, and data and programs are stored in secondary memory.
Data is stored as lots of binary numbers, by magnetism, electronics or optics. … The computer’s operating system, for example, contains instructions for organizing data into files and folders, managing temporary data storage, and sending data to application programs and devices such as printers.
Magnetic storage is commonly used on the hard disc drives found on most computers. Information is stored using positive and negative magnetic charges to correspond with the 1s and 0s noted above. Optical discs like CDs and DVDs store information as binary code that can be read by an optical sensor in a disc drive.
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