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Definition: computer

A computer is a general-purpose machine that processes data according to a set of instructions temporarily or permanently stored internally. The computer and all the equipment attached to it are "hardware." The instructions that tell the computer what to do are "software." See data processing and machine language.

The software that controls the computer is called an "operating system," and the software that inputs, processes and outputs data for the user is called a "program," "application" or "app." See operating system, application, how to select a computer and computer generations.

Storage/RAM Interaction
The interplay between storage and RAM (memory) is how computers, tablets and smartphones work. The program is first written into RAM, and the computer executes its instructions to input, process and output the data. In appliances and sensors, a single program is stored permanently (see non-volatile memory). See stored program concept and 3 C's.

RAM and Storage
RAM is a temporary workspace, while storage is permanent and comprises any hard drive, solid state drive (SSD), optical disc or USB drive in the same computer or in another computer in the network. After processing the data internally, the computer can send a copy of the results from RAM back to storage, to a printer or to another computer. The more RAM, the more programs and data the computer can work with quickly, and entry-level computers generally have at least 4GB (four gigabytes) of RAM. The more storage, the more data can be saved. Entry-level computers typically have at least 512GB of disk or 256GB of SSD storage.

Addressable RAM
Storage is read and written in large blocks called "sectors" that hold thousands of bytes. However, it is the RAM that allows one or more bytes to be manipulated independently. This single-byte "addressability" is why data are brought into RAM for processing. See byte addressable, RAM and storage vs. memory.

The UNIVAC I (Frankfurt Germany, 1956)
Imagine being here and watching one part of a UNIVAC CPU being pushed up the ramp and someone says "you know some day all of that will fit on the head of a pin." See UNIVAC I.

How About the Tip of a Pencil?
In fact, these PICmicro microcontrollers from Microchip (www.microchip.com), are a whole lot faster than the UNIVAC I. See microcontroller.

Ordenador and Ordinateur
In Spain and France, a computer is an "organizer." The word is surely less intimidating than "computer," and in fact, computers do as much or more organizing and rearranging than they do deriving mathematical results. See computers are copy machines.