What is a computer?

A computer is a programmable machine. The two principal characteristics of a computer are: It responds to a specific set of instructions in a well-defined manner, and it can execute a prerecorded list of instructions (a program).

Modern computers are electronic and digital. The actual machinery wires, transistors, and circuits are called hardware; the instructions and data are called software.

Computer System

All general-purpose computer systems require the following hardware components:

What are the parts of a computer?

A computer has four main components: a CPU, a graphics processing unit (GPU), random access memory (RAM), and either a solid state drive (SSD) or a hard disk drive (HDD). All of these components are connected to a motherboard. Typically, the GPU and CPU comprise the computer’s chipset. The memory (RAM) and storage (SSD/HDD) components are typically easier to modify or replace than the chipset.

When was the first computer invented?

The first mechanical computer was developed in the early 19th century by Charles Babbage, an English engineer, and Ada Lovelace, a mathematician. At the computer’s core was the Difference Engine, which was responsible for making calculations using multiple sets of numbers printing the outputs.

The first digital computer was the Atanasoff-Berry Computer (ABC). The ABC was developed in 1942 by Iowa State University professor John Vincent Atanasoff and graduate student Cliff Berry. This computer used vacuum tubes to make binary computations and processed Boolean logic. However, the ABC lacked a CPU and was, therefore, not programmable. Subsequent computer evolutions added programming capabilities, RAM, transistors, microprocessors, and portability as key characteristics.

What are the different types of computers?

As referenced below, there are six core classifications of computers:
Microcomputers, or personal computers
Mainframe computers
Workstation computers

How to build your own computer

It’s easy to build your own computer for under $1000. TechRepublic’s Jack Wallin shows you how.


Now that you’ve watched the video, shop computer components here, including your CPU, GPU, RAM, SSD, HDD, and your motherboard.

Computer classification: by size and power

Most people associate a personal computer (PC) with the phrase computer. A PC is a small and relatively inexpensive computer designed for an individual user. PCs are based on microprocessor technology that enables manufacturers to put an entire CPU on one chip.

Personal computers at home can be used for a number of different applications including games, word processing, accounting, and other tasks.

Computers are generally classified by size and power as follows, although there is considerable overlap. The differences between computer classifications generally get smaller as technology advances, creating smaller and more powerful and cost-friendly components.

Personal computer: A PC is a small, single-user computer based on a microprocessor. In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving data.

Workstation: A workstation is a powerful, single-user computer. A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality monitor.

Minicomputer: A minicomputer is a multi-user computer capable of supporting from 10 to hundreds of users simultaneously.

Mainframe: A mainframe is a powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously.

Supercomputer: A supercomputer is an extremely fast computer that can perform hundreds of millions of instructions per second.

An emerging trend that attempts to go beyond the binary limitations of traditional computing is quantum computing

Recommended Reading: Webopedia’s Computer Architecture Study Guide is an introduction to computer system basics.

Vangie Beal
Vangie Beal
Vangie Beal is a freelance business and technology writer covering Internet technologies and online business since the late '90s.
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