Computer Hardware

This article:

  • Compares characteristics/uses of different types of computers and networks
  • Describes how computers represent data internally
  • Describes the five functions of hardware and give examples of each
  • Differentiates between operating system software and application software and see how hardware and software work together to create a computer system
  • Discusses health hazards and environmental considerations related to computers

Computer Hardware Overview

Types of computers

Supercomputer Weatherforecasting, research, security Centralized computer Dumb terminals
Mainframe Government, universities, corporations
Minicomputer Medium sized Businesses, Organizations
Personal Computing
Business, Education, Government
(network clients)
Internet enabled
Smart Phone
Mobile and Ubiquitous
Mobile Handheld
Touch screen

Computer networking

In a client/server network, the network servers are dedicated machines which provide centralized network security and share their hardware and software resources with connected clients. To connect, clients must be authenticated (user name and password) by the server. Once connected (logged in), users are free to use resources for which they have been granted permissions by a network administrator. Client/server networking is complex, but relatively secure and networks can be very large.

Peer-to-Peer networks are favored by small businesses because they are much simpler to set up and manage. In a peer-to-peer network each connected computer acts as both a workstation (equivalent to a client in a client/server network) and a server. Therefore every workstation can share its resources with all others. Security is decentralized and weak and this type of network is only practical for small numbers of computers.

Cloud computing is a term applied to many different computing arrangements which all have one thing in common: they involve using, for a fee, a server on the Internet, either as a source of application software, or as a data repository, or both.

Microprocessor advancement, 1986-2012

Future of computers

  • DNA computers
    Leonard Adleman (USC) 1994 carried out simple computation using DNA. DNA computers are slow and don't always achieve the same result. But, 1tsp DNA has storage capacity equivalent to 12 trillion 200 Gb RAM chips.
  • Molecular computers
    California Institute of Technology 2007 created 160-Kbit memory chip the size of a white blood cell (.0005") Molecular switches (rotaxane molecules) achieved a bit density of 100 billion per square cm (100 times current technology). Wires used in the "chip" were the width of a protein. (January 2007. NY Times)
  • Quantum computers: "Exploit quantum effects to solve search and optimization problems"
    "fabricated using superconducting metals instead of semiconductors"
    "operated at ultra-low temperatures in a magnetic vacuum"
    Make strange eerie sounds, especially at night
  • Supercomputers: ways to reduce power consumption Can require 3.3 megawatts per hour today Cooling expense is 1 dollar for each 5 cents worth of computing electricity New Laval U Mtl QC) supercomputer uses 30% less power, and recycles heat

Data representation and storage

  • Computers represent data using the binary number system
  • Binary number system uses only two digits - 1 and 0
  • Binary numbers are referred to as bits (binary digits)
  • 8 bits = 1 byte
  • A byte is the storage capacity required to represent one character
  • Kilobyte (Kb) = 1,000 bytes; megabyte (Mb) = 1,000,000; gigabyte (Gb) = 1,000,000,000; terabyte (Tb) = 1,000,000,000,000 bytes
  • ASCII is a standard reference for representing characters using numbers

For more details, see "Bits, Bytes, and ASCII".

Check this. The human brain stores memories as synaptic connections between neurons. The average adult human brain has between 500 trillion to 1,000 trillion synapses. Compare this with 32 trillion bytes of information in the entire Library of Congress. (Foer, Joshua. "Remember This". National Geographic. Page 36, November 2007.)

Computer systems

Every computer system requires both software and hardware to function.

Hardware accepts, stores, manipulates, and displays our information and data, but it can only do so according to instructions which must be supplied by software programs.


Functions of hardware

All hardware devices perform one of five different functions:

1. Input

Input devices are used to generate and enter data

  • KB, mouse, touchpad, joy-stick, push-stick, touchscreen
  • Scanner, digital camera, microphone
    Note: USB, and serial and parallel ports are connectors, see below

2. Output

Output devices display the results of computations and processing

  • Monitors
    Two major types:
    Liquid Crystal Display (LCD)
    Cathode Ray Tube (CRT)
    Nitrogen trifluoride, used in LCD monitors semiconductor production, is 17,000 times more damaging to the environment than carbon dioxide and is not covered by the Kyoto Protocol. (NY Times, 3 September 2008). Resolution, the measurement of image quality, is the number of pixels (picture elements) a monitor can display: more pixels=higher resolution=better quality.
    Dot pitch> is the distance between pixels: smaller=pixels closer=sharper image.
  • Printers
    Laser and inkjet (non-impact); dot matrix and daisy wheel (impact)
  • Heads up displays - holograms
  • Speakers, headphones
  • 3. Primary Memory

    Primary memory>, which can be thought of as the computer's "workbench", is where data and instructions are stored during processing.

    • Random Access Memory> (RAM) RAM is volatile>, meaning that content is lost when power is removed (shutdown)
    • Virtual Memory> (VM) simulates more RAM than is actually physically installed

    4. Secondary Memory

    Secondary memory> is "permanent" memory. It is where data and programs are stored in order to conserve them from one computing session to the next after a computer has been shut down.

    • Magnetic media - hard disk drives (HDD), diskettes, tape
    • Optical storage devices - CD-ROM's, DVD's
    • Digital memory - USB drives and other memory cards
    • PC secondary storage is typically measured in gigabytes (Gb) or terabytes (Tb)

    Other Memory devices

    • ROM - low-level operating system instructions permanently burned onto a chip
    • CMOS - hardware configuration information saved to a chip - can be changed

    5. Processing

    The Central Processing Unit> (CPU) executes software instructions to process data.

    • CPUs for desktop and laptop computers are also known as microprocessors.
    • Speed measured in gigahertz> (Ghz); today's cpu's top out around 4 Ghz.
    • CPUs communicate with other components using a data bus (see below).

    Motherboard and data bus

    The motherboard> is a computer's main printed circuit board, it holds the microprocessor (CPU) and primary memory (RAM) as well as various other circuitry.

    • A motherboard's data bus> (bus) is a set of 32 or 64 conductors which connects the CPU with RAM, secondary storage, and all input/output ports.
    • Expansion slots> are connectors on a motherboard which accept expansion cards. Expansion cards are smaller circuit boards designed for specific jobs such as sound processing, video display, or network connections. Expansion slots provide a direct connection between an expansion card and the bus and CPU.


    Serial>, parallel>, and USB ports> are standard types of connectors that permit external input and output devices (keyboards, mice, cameras, printers, etc.) to exchange data with motherboard and expansion card circuitry.

    Serial and parallel ports can only accommodate one device at a time. They have been largely supplanted by USB ports, each of which can accommodate up to 255 devices at the same time.


    Software> is the term used to describe computer programs. Programs are sets of instructions (algorithms) which accomplish specific tasks. There are two major categories of software: operating systems>, and applications>.

    Applications software

    Applications> ("apps") are programs that enable us to achieve real world tasks. Examples:

    • Word-processing
    • Spreadsheet
    • Database
    • Graphics
    • Communications

    However, applications can't be used all by themselves; in addition to hardware, they require the support of an operating system>.

    Operating systems (OS)

    An operating system> is a program (actually a very large collection of programs) whose specialty is working with hardware to provide the most basic computer operations and resources required by application programs to carry out their own special tasks.

    These basic functions of operating systems are:

    • Manage processes- launch and monitor all processes (including application programs) and handles errors
    • Manage resources - operate and monitor all hardware, including input and output devices, primary and secondary storage, and the cpu
    • Manage data - maintain a filing system for data created by application programs and save and retrieve it on their behalf

    All operating systems include a user interface> (UI). A user interface provides the method by which a computer user communicates with computer software and hardware.

    A GUI is a graphical user interface> (as opposed to older character-based operating systems such as DOS). WIMP is sometimes used to describe a graphical user interface that makes use of Windows, Icons, and a Mouse.

    MS-Windows, Linux, Unix, and Apple OS are all examples of operating systems for personal computers.

    The process of applying power to computer hardware and loading an operating system into RAM to make the computer system operational is known as booting a computer.

    Health issues and Computers


    Health problems known to be caused or aggravated by computer use include carpel tunnel syndrome, repetitive stress injuries (RSI), eyestrain, back problems, heart disease, diabetes, and addiction.

    Forced inactivity is the major health risk incurred by computer users. A 2009 Canadian study (Katzmarzyk) showed that even if they exercise regularly, the more an individual sits, the higher their risk of death from obesity, diabetes, and cardiovascular disease.

    Researchers at the Swedish School of Sport and Health Sciences confirm that inactivity is a killer. They recommend that computer users leave their seats and move around for five out of each forty-five minutes.

    Ergonomics> is the study of design with consideration to human anatomy and physiology. Its goals are to reduce health risks while simultaneously increasing productivity.

    Specially designed keyboards and mice help reduce physical stress, and ergonomic computer furniture provides less stressful working positions and encourages better posture.

    Ergonomic software incorporates features and techniques aimed at reducing the physical effort required to accomplish tasks like data entry and formatting.

    This course will cover many labor and time-saving techniques, including keyboard shortcuts, efficient scrolling and selection methods, and features such as styles.


    The production, use, and disposal of computing equipment are all major contributors to environmental pollution.

    Phosphors, nitrogen trifluoride, mercury, lead, arsenic, cadmium, beryllium, and brominated flame retardants are a few of the pollutants released into the environment through production and improper disposal of computer components.

    Each year Americans discard 3 million tons of electronic waste (Wikipedia). Of the 130 million cell phones discarded by Americans, only ten percent are recycled (CBC Radio The Current 27 Sept 2012). Most of the rest wind up in landfills where their toxicity is released into the water table.

    The use of computers is also a major source of air pollution (millions of tons of greenhouse gases) and wasted energy (in excess of a billion dollars a year by corporations alone) according to the Environmental Protection Agency (NPR Morning Edition 17 June 2004).

    Evidence is emerging that cloud computing is rapidly becoming a major source of pollution worldwide. Extensive investigations by the New York Times indicate that up to 90% of the 30 billion watts of energy consumed by data warehouse centers at any given moment is wasted. (New York Times online. "Power, pollution, and the Internet". 22 Sept 2012).

    Bruce Miller 2010, 2014