The Basics of Computing
• What is a Computer
• Types of Computers
• Computer Hardware
• Computer Software
• Communication Networks
What is a Computer?
A computer is a device that accepts
input, manipulates it under a sequence of
(a program) and produces an output. This process
is called the “Information Processing Cycle.”
The output can be the result of a calculation or just
an acknowledgement of the input.
Input Processing Output
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Handheld devices such as these
are also computers…
However, we‟re concerned with
just 3 types of computers that are
used for business information
• industry term for a large computer
• modularized to reduce overhead
• used in centralized computing environments
• large-scale computing server
• high volume
• high overhead processing
• used as large database servers
Mainframes typically cost hundreds of thousands
of dollars and are manufactured by companies
such as Hitachi, IBM and Amdahl.
Diagram of a Simple Mainframe Configuration
P C W orks tations
F ront-End M ainfram e
or term inals
P roc es s or
(F EP )
• smaller than a Mainframe
• larger than a PC (Microcomputer)
• have become the “mid-range” server
• IBM‟s AS/400 is an example
• Personal Computers (PCs)
• desktop computing and client-server
• can serve both as a client and a server
• are generally categorized by the CPU type
• Intel – IBM compatible
• Motorola – Apple / MacIntosh / Power PC
• Sun - SPARC
Microcomputers are what we think of as PCs.
Although they cross the line at times, Sun
Microsystems generally is thought to manufacture
Basic Parts of a PC
Components of a Computer
A computer needs the following devices to function:
• Input device(s)
• Processing Unit
• Output device(s)
• Storage device(s)
This is the computer‟s hardware…it is tangible.
Accept data for the computer to work with…
The Central Processing Unit, or CPU, is the brains
of the computer. It controls all activity and performs
operations on data based on its instruction set. The
CPU is made up of several major units as
The CPU consists of these main elements:
• Control Unit - executes the instructions as interpreted
• Arithmetic / Logic Unit - performs mathematical and
• Registers - serve as the short term memory for
the ALU‟s computations and provides some
reserved space for certain functions
• Clock Unit - generates pulses that determine the
speed of instruction processing, the rate is
measured in megahertz (Mhz)
The CPU has two main features:
• Its speed measured in millions of instructions per
second, or MIPS
• Its word size is the number of bits the CPU can
process at a time. An 32-bit processor
manipulates 32 bits simultaneously.
A PC has three basic types of memory:
• Cache memory that is built into the CPU (not the
CPU registers) called L1 or L2 cache
• Read Only Memory (ROM) that is used to “boot”
the system (among other applications)
• Random Access Memory (RAM) which is the main
memory that acts like the workshop or
desktop of the CPU
The purpose of an output device is to present
electronic data (and the results of our work) in a
form that can be understood and used. For
example, think how hard it would be to use a
computer without a monitor.
Typical output devices on a PC are:
• Printer or Plotter
• CRT – Cathode Ray Tube, like a Television
• LCD – Liquid Crystal Display
• TFT – Thin-Film Transistor
• Laser printers
• Thermal Wax
Auxiliary Storage Devices
These devices, also known as secondary storage,
are where the PC stores data that must last from
session to session. Basically speaking this is the
permanent data storage.
Though they differ in their technologies and
methods of storage, the result is the same; the
PC can easily retrieve the stored data for use at a
These components are many times referred to as
Mass Storage devices.
Auxiliary Storage Devices
Types of Auxiliary or Mass Storage devices are:
• Floppy disk drive
• Hard disk drive
• Optical disks (Compact discs, DVD)
• Zip drives
• Jazz or Bernoulli drives
• Tape drives
• Flash memory
Software is computer instructions (Programs) and
Anything that is electronically stored on a computer
storage device is considered software.
It is intangible and exists only electronically.
Two general types of software:
• System software
• Application software
Systems software are the programs that control
the computer and manage its resources. Such as
operating systems and system utilities.
Operating systems perform the basic tasks of
computing like managing the input and output of
data and interpreting the instructions of the
System Utility software performs more basic
functions such as file management or backup, but
they must work under an operating system.
O pe r ati ng
Sys te m
H E WL E TT 4 0 0 0 T
P ACK A R D
G A T E W A Y 2000 V I V I T R ON
The Operating system connects components and
directs the flow of data.
Examples of Operating systems:
• Windows (XP, 2000, ME, 98, 95, 3.1, CE)
• DOS (MS-DOS, DR-DOS, PC-DOS)
• Mac OS X
• Unix (Solaris, FreeBSD, SCO UNIX)
• Palm OS
Operating systems are written to run on specific
Examples of Utility software:
• Anti-virus software
• Norton, McAfee, Sophos, Trend Micro
• File Management
• PKZip, WinZip, Norton SystemWorks
• Disk Utilities
• PartitionMagic, System Commander
• Retrospect, Backup MyPC
Utility software is written to run under specific
Application software consists of programs that
help you work and play on the computer. This
category includes word processors, games,
spreadsheets, drawing and other “productivity”
This is the bulk of all software written.
Application software is written to run under specific
aka Computer Networks
Two or more computers connected to share data
and resources are “networked.” The simple idea
behind computer networking is to allow users to
access more information and give them access
to devices not directly attached to their “local”
system, such as printers or storage devices.
Two of the main types of computer networks are:
• LAN - Local Area Network
• WAN - Wide Area Network
A LAN is comprised of computers located within
close proximity, such as in an office or building.
A WAN is a network of computers that are situated
further apart, but still connected. Such a network
might be of computers within a single state agency
or of a multi-national corporation worldwide.
A PC must have a Network Interface Card installed
to connect it to a network. The cards, frequently
called “nics”, come installed in many new computers
as they are also used for cable modem and DSL
The computers can be configured in several ways,
the most popular of these “architectures” are
peer-to-peer and client/server. The first is a loose
connection of local computers with no central
authority, the later relies on a “server” to manage
the network and its resources.
P eer-to-P eer N etw ork
A peer-to-peer network requires the computers to be
connected to each other by a network cable, usually
an “unshielded twisted pair” cable known as “CAT 5”.
Connecting more then two computers require the
use of a network hub as shown.
Client/S erver N etw ork
N etw ork S erver
A client/server network uses a computer known as
the server to manage the network and control access
to resources. The computers can be connected
using various types of cable including CAT 5, coaxial
and fiber optical.
Local Area Networks are configured in 3 basic
topologies. These are either the logical or
physical way the computers are connected. Each
connection on the network is known as a node.
These topologies are:
A Star topology connects all the nodes directly to the
server or to a connecting device such as a hub.
All nodes on a Bus topology are connected to a
central line or backbone.
Nodes on a Ring topology are connected in a closed
loop. This means that each node has two connections,
one in and another out. Using this type of topology
the data must travel through all the nodes.
Computer Network Software
Computer networks use special operating systems
and other system software to manage the network,
its resources and its users. Network Operating
Systems (NOS) should be very secure and robust
to provide reliable network services.
Examples of such software are:
• Windows 2000 Server
• Novell NetWare
• Unix…too many flavors to link them all
The Internet is a worldwide computer network.
Actually it is a loose collection of networks. There
is no central control or authority, all cooperation
is voluntary to a degree…
Users access the Internet by using a network that
is connected to a “backbone” usually through an
Internet Service Provider (ISP). The real access
path to the „net is through a Network Access Point
The World Wide Web
The World Wide Web is a collection of computers
connected via the Internet that support the use of
documents written in HyperText Markup Language
The “web” uses the HyperText Transfer Protocol
(HTTP) as the standard for the formatting and
transmission of these documents.
Not every server on the „net uses HTTP, and
therefore is not part of the Web.
The Internet is very large and diverse, there is no
one method of access and there are many protocols
used such as:
• NNTP - Network News Transfer Protocol for
• SMTP - Simple Mail Transfer Protocol for sending
• FTP - File Transfer Protocol used for sending files
It’s a wonder it works so well, much less at all.
Hobbes' Internet Timeline: