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CIS-100

Chapter 2—History of computers

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Chapter Objectives

After successful completion of this chapter you should be able to:

  Understand how computers began and evolved into what

they are today Identify common computer terms and understand basic

computer functions Be able to identify the different types of computers Understand how computer networks and the internet work Be able to differentiate between computer hardware and

computer software Have a basic knowledge of several programming languages

and what they are used for

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The Jacquard Loom

The Jacquard Loom was one of the first programmable devices.

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What is a computer?

A computer is a machine that manipulates data according to a list of instructions.

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Components of a Computer

There are six primary components of a computer:

Input Devices The Processor Memory Output devices Storage devices Communication devices

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Input Devices

Input Devices are any hardware components that allows you to enter data, programs, commands, and user responses into a computer.

Some of the most popular input devices include:

Keyboard Mouse

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The Processor

Central Processing Unit (The Processor)—interprets and carries out the basic instructions that operate a computer.

 The processor is made up of two different

components:  Control Unit—interprets the instructions that

operate a computer.  Arithmetic/Logic Unit—performs the logical and

arithmetic processes that operate a computer.

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Memory

Random Access Memory (Ram)—consists of electronic components that temporarily stores instructions waiting to be executed by the processor, data needed by those instructions, and the results of processed data (information).

Byte Abbreviation Value Bit b = 1 or 0 representing switch states on or off Byte B = 8 bits, 1 byte (1 character) Kilobyte KB = 1,024 bytes (1000 characters) Megabyte MB, = 1,048,576 bytes (1 Million characters) Gigabyte GB, = 1,073,741,82 4 bytes (1Billion

characters) Terabyte TB, = 1,099,511,628,000 bytes (1 Trillion chars)

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Output Devices

Output Devices—make the information resulting fromprocessing available for use. The output fromcomputers can be presented in many forms, such as a printed report or displayed on a screen.

The two output devices more commonly used are the

printer and the monitor.

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Display Devices

Display Devices are an output devices that visuallyconvey text, graphics, and video information.

A monitor is a common example.

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Storage Devices

Storage devices are used to store instructions, data, and information when they are not being used in memory.

The most common storage devices are: USB Drives (Today's equivalent of the

Floppy) Hard disk drive CD-Rom (Compact Disk) DVD-Rom (Digital Video Disk)

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Hard Disk Drive

Magnetic Media Capacity

Megabytes Gigabytes Terrabytes

Disassembled hard drive http://hddscan.co

m/doc/HDD_from_inside.html

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Optical Disks

650 – 700 MB 2 types

Recordable (CD-R) Write until full or

finalized. No Rewrite

Rewriteable (CD-RW) Write and rewrite

until finalized

4 – 8 GB Approx 4 GB single

layer Approx 8 GB dual

layer Blue Ray (High Def)25-50 GB,

dual layer 50-100 GB

Compact Disc (CD) Digital Video Disk (DVD)

Recordable Re-Writeable

DVD +R DVD +RW

DVD - R DVD - RW

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Communication Devices

Communication devices are hardware components that enable a computer to send (transmit) and receive data, instructions, and information to and from one or more computers. As such they are also Input/output Devices.

Widely used communications devices are the NIC (Network Interface Card), modem, and cable modems.

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Multitasking

Multitasking is the ability to run more than one program at the same time. 

For instance, many people like to run Internet Explorer along with their word processing software. 

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Types of Computers

There are four common types of computers:

Desktop Laptop Handheld Tablet PCs

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Desktop Computers

Desktop computers are designed for use at a desk or table. They are typically larger and more powerful than other types of personal computers. Desktop computers are made up of separate components. The main component, called the system unit, is usually arectangular case that sits on or underneath a desk.

Other components, such as the monitor, mouse, and

keyboard, connect to the system unit.

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Laptop computers

Laptop computers are lightweight mobile PCs with a thin screen. They are often called notebook computers because of their small size. Laptops can operate on batteries, so you can take them anywhere. Unlike desktops, laptops combine the System Unit, CPU, screen, and keyboard in a single case. The screen folds down onto the keyboard when not in use.

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Handheld Computers

Handheld computers, also called personal digital assistants (PDAs), are battery-powered computers small enough to carry almost

anywhere.

Although not as powerful as desktops or laptops, handhelds are useful

for scheduling appointments, storing addresses and phone numbers,

and playing games. Some have more advanced capabilities, such as

making telephone calls or accessing the Internet. Instead of keyboards,

handhelds have touch screens that you use with your finger or a stylus (a pen-shaped pointing tool).

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Tablet PCs

Tablet PCs are mobile PCs that combine features of laptops and handhelds. Like laptops, they're powerful and have a built-in screen. Like handhelds, they allow you to write notes or draw pictures on the screen, usually with a tablet pen instead of a stylus. They can also convert your handwriting into typed text. Some Tablet PCs are “convertibles”

with a screen that swivels and unfolds to reveal a keyboard underneath.

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Networking and the Internet

Networking is a series of computers linked and working together. In every small, medium, or large organization, there is a need for Networking. Networking means linking computers together to share resources, and information.

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Local Area Network

A local area network (LAN) is a network of computers linked together via a cable covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport.

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Wide Area Network

Wide Area Networks (WANs) are computers linked together via phone, satellite or any other media. Such computers are usually scattered in different locations.

A Wide Area Network (WAN) is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies. The largest and most well-known example of a WAN is the Internet.

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Internet

The Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP). It is a "network of networks" that consists of millions of private networks.

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IP Address

“Phone Number” for the computer/device Any device connected to network has one

Approx 4.6 Billion Addresses 5 Classes

Class A: (8 bit) Approx 128 networks Range: 0.0.0.0 - 127.0.0.0

Class B: (16 bit) Approx 16,384 networks Range: 128.0.0.0 – 181.255.0.0

Class C: (24 bit) Approx 2,097,152 networks Range: 192.0.0.0 – 223.255.255.0

Class D: Multicasting Range 224.0.0.0 – 239.255.255.255

Class E : Experimental

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IP Address

128.179.48.124

Segment 1 (128): Similar to a country code in phone #

Segment 2 (179): Similar to a area code in phone #

Segment 3 (48) Similar to phone prefix (local area)

Segment 4 (124) Similar to last 4 of a phone # line specific.

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Computer Hardware

Input Devices: Keyboard, Mouse, Scanner, and Joystick

Output Devices: Monitors, and Printers

Input/Output devices: Floppy disk, Hard disk, and writeable CDs, and DVDs

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Computer Software

Computer software is the key to productive use of computers. With the correct software, a computer can become a valuable tool. Software can be categorized into two types:

  System Software Application Software

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System Software

System software consists of programs to control the operations of computer equipment. An important part of system software is a set of programs called the operating systems. Instructions in the operating system tell the computer how to perform the functions of loading, storing, and executing an application program and how to transfer data. For a computer to operate, an operating system must be stored in the computer’s memory. When a computer is turned on, the operating system is loaded into the computer’s memory from auxiliary storage. This process is called booting.

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Application Software

Application software consists of programs designed to make users more productive and/or assist them with personal tasks. Some widely used application software includes web browsers, personal information managers, project management, accounting, computer-aided design, desktop publishing, paint/image editing, audio and video editing, multimedia authoring, web page authoring, personal finance, legal, tax preparation, home design, educational, and games.

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Programming Languages

Programming languages provide various ways of specifying programs for computers to run.

There are thousands of different programming languages—some intended to be general purpose, others useful only for highly specialized applications.

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Flowchart

A flowchart is common type of chart, that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting these with arrows. Flowcharts are used in designing or documenting a process or program in various fields.

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Flowchart Symbols