Basic Computer Hardware Components

Basic Hardware Components

  Arithmetic/logic unit

Contains the electronic circuitry necessary to perform arithmetic and logical operations on data.

  Communications Devices

Enable a computer to connect to other computers. Devices that enable a computer to connect to other components; includes modems and network interface cards.

  Control Unit

The component in any computing system that works in coordinatin with the central processing unit to instruct, maintain and control the flow of information.

  Central Processing Unit (CPU)

The component in any computing system that represents the circuitry necessary to interpret and execute program instructions, it consists of the Control Unit, arithmetic/logic unit and the controller..  It is the corollary to the brain in organic systems.


Equipment that inputs, processes, outputs, and stores data.  It consists of input devices, a system unit, output devices, storage devices, and communication devices.

  Input Devices

Any computer peripheral used to enter data and/or control signals into a computer system. Some devices, such as modems, are capabile of both input as well as output.

  Examples of Input Devices

Biofeedback Input Devices—special equipment like gloves, body suits, and eyeglasses to translate movements, temperature, or skin-based electrical signals

Digital Camera—record photographs in the form of digital data that can be stored on a computer.

Digitizer—converts points, lines, and curves from a sketch, drawing, or photograph to digital impulses and transmits them to a computer

Electronic Whiteboard—captures anything drawn on special whiteboard

Joystick—uses the movement of a vertical stem to direct the pointer.  These are often used with computer games and have buttons you can press to activate events, depending upon the software.

Graphics Tablet—similar to a digitizer, but it also contains unique characters and commands that can be generated automatically by the person using the tablet

Image Scanner (page scanner)– an input device that can electronically capture an entire page of text or images such as photographs or art work.

Keyboard—most commonly used input device.  You enter data by pressing keys on the keyboard

Light Pen—used by touching it on the display to create or modify graphics

Microphone—used to record sound.

Modem—a device that converts data into a form suitable for both receipt and transmission by wire or radio such that it can be reconstructed at the destination point.

Mouse—a small palm-sized input device that you move across a flat surface to control the movement of the pointer on the screen

Pen Input—used to  (1) input data using hand-written characters and shapes that the computer can recognize (2) as a pointing device like a mouse to select items on the screen, and (3) to gesture (special symbols made with the pen that issue a command)

Optical Recognition Devices—use a light source to read codes, marks, and characters and convert them into digital data that can be processed by a computer

Pointing Stick (trackpoint or isometric pointing device)—a small device shaped like a pencil eraser that moves the insertion point as pressure is applied to the device

Terminals—consist of a keyboard and a screen – commonly used for special purpose input such as POS (Point-of Sale) information entry.

Touchpad (trackpad)—a flat rectangular surface that senses the movement of a finger on its surface to control the movement of the insertion point

Touch Screen—allows you to touch areas of the screen with your fingers to enter data.

Trackball—A pointing device like a mouse only with the ball on the top of the device instead of the bottom

  Laptop or Notebook or Netbook

A portable, integrated device in which the central processing unit (CPU), storage (hard disk and/or memory), input system (keyboard, trackpad, etc.), display and various data input and output channels (USB, Firewire, Ethernet, WiFi, etc.) are combined in a self-contained unit. Laptop or Notebook or Netbook computers are generally smaller than desktop computers, lending to their portability.

  Machine cycle

Machine Cycle or Processor Cycle or Instruction Cycle: the most basic logical mode of operation in a central processing unit (CPU). It consists of four steps that are “executed” continuously at a very high rate of speed: fetch, decode, execute and store. Only one execution cycle per machine cycle may be performed.


Integrated circuits that temporarily store program instructions and data that can be retrieved.  Basic unit of memory is a byte.

  RAM (Random Access Memory) – a volatile form of memory, RAM generally functions as a computers “desktop” – the space in which data that is actively under review and/or manipulation can be processed.  As a result and as a general rule, the more RAM with which a computer is fitted, the more and faster data can be viewed and manipulated.  RAM needs to be cyclically “refreshed” from an outside power source in order to maintain the information contained therein.  When external power is removed, the data contents held in RAM disappears.  For this reason, RAM is sometimes referred to as short term memory.

  ROM (Read Only Memory) – a non-volatile form of memory, ROM stores data that does not commonly change, like startup instructions and data used when a computer if first turned on.

  CMOS –used to store information about the computer system, such as the amount of memory, the type of keyboard and monitors, and the type and capacity of disk drives.

  Output Devices

Devices that convert the results of processed data into a form that can be used and understood by the user.  A computer display is an example of an output device, as is a printer.  Whereas a computer display uses a screen to present visual information in virtual form, a printer produces hardcopy – a tangible form of the data or information. Audio speakers are another form of output device, converting electronic programming into human-audible sound.  Some devices are capable of being output as well as input devices.

  Examples of Output Devices

Computer display or monitor

Plotter- Designed for line drawing; often used for computer-aided design; some units can handle large paper sizes

Modem—a device that converts data into a form suitable for both receipt and transmission by wire or radio such that it can be reconstructed at the destination point.

Multifunction Devices—Combines printer, fax, scanner, and copier



  Palmtop, PDA or PIM

Commonly the smallest of computing platforms, these are highly portable computing devices used primarily to organize task, contact, communications and other personally oriented information and data. These systems often have many of the same resources as a Laptop or Netbook computer: a CPU, storage, input system, display and one or more data input/output (I/O) channels. These devices can be purpose-built, or can have other primary functions, with smartphones being a good example of such a multifunction device.

  Peripheral Devices

A general term for any device connected to the system unit .

  Storage Devices

Store instructions and data when they are not being used by the system unit.

  Examples of Storage Devices

CD-ROM (compact disk read-only) — a smaller optical disk that can store about 450 times the data on a floppy

Data Cartridges—removable hard disk drives that provide both the storage capacity and fast access

Floppy disk/drive—a flexible platter coated with material that allows data to be recorded magnetically on the surface of the platters.

Hard Disk—one or more rigid platters coated with material that allows data to be recorded magnetically on the surface of the platters.

Smart Cards—size of credit card and contain a thin microprocessor capable of storing data. They are used as attendance tracking cards, identification cards, telephone cards, etc

Tape Cartidges—containing a long ribbon of plastic, one side of which is coated with a material that can be magnetized to record the binary codes that represent data.

  System Unit

Box-like case that contains the electronic circuits that cause the processing of data to occur. Part of the computer system where the computing is done.  This is where the computer programs are executed and the data is manipulated.  It consists of the Central Processing Unit (CPU), memory (Random Access Memory-RAM), and other electronics.