Computer Basics

Copyright 2005 - 2009: Hi Tech Criminal Justice, Raymond E. Foster
Police TechnologyPolice Technology
Chapter TwoChapter Two
ComputerComputer BasicsBasics

Copyright 2005 - 2009: Hi Tech Criminal Justice, Raymond
Learning ObjectivesLearning Objectives
 Understand the basic hardware andUnderstand the basic hardware and
software components of asoftware components of a Desk TopDesk Top
Personal Computer (PC).Personal Computer (PC).
 The difference betweenThe difference between OperatingOperating
SystemsSystems andand Applications softwareApplications software..
 The difference between andThe difference between and Flat FileFlat File
andand Relational DatabaseRelational Database

Binary Number SystemBinary Number System
A mathematical countingA mathematical counting
schemescheme
that has only two digits – zerothat has only two digits – zero
(0) and one (1) which are(0) and one (1) which are
combined to represent our ten-combined to represent our ten-
digit counting scheme.digit counting scheme.
Today’s computers use thisToday’s computers use this
off/on scheme to representoff/on scheme to represent
thethe binary digitsbinary digits, commonly, commonly
referred to asreferred to as bitsbits, 1 and 0., 1 and 0.

It is simple for computers to translate binaryIt is simple for computers to translate binary
digits into a sixteen digit-based code calleddigits into a sixteen digit-based code called
hexadecimalhexadecimal. This coding system is a. This coding system is a
compromise between our abilities and thecompromise between our abilities and the
computer that allows us tocomputer that allows us to interface.interface.
Binary Number SystemBinary Number System

ASCIIASCII
The standard computer code configurationThe standard computer code configuration
that works with computer bits is called thethat works with computer bits is called the
American Standard Code for InformationAmerican Standard Code for Information
Interchange (ASCII).Interchange (ASCII).
A byte is eight bits,
or a series of eight ones
and zeros.
Binary digits
Byt
e
ASCII
Words you can read!

Interface Means to InteractInterface Means to Interact
 User interface is howUser interface is how
we interact with thewe interact with the
computer, e.g. thecomputer, e.g. the
keyboard and mousekeyboard and mouse
are user interfaceare user interface
inputsinputs and theand the
monitor is themonitor is the
computer’s usercomputer’s user
interfaceinterface outputoutput

A computer system can considered asA computer system can considered as
three broad categories of components:three broad categories of components:
 HardwareHardware
 SoftwareSoftware
 FirmwareFirmware
Your Computer as a SystemYour Computer as a System

Your Computer as a SystemYour Computer as a System
The user is a human being.
The input devices are the
computer keyboard, mouse,
and microphone.
The output devices are the
monitor, speakers, printer,
and various storage media.

HardwareHardware
Input/output devices areInput/output devices are
referred to asreferred to as peripheralperipheral
devicesdevices. Think of a. Think of a
peripheral device as anyperipheral device as any
devicedevice notnot inside theinside the
computer case.computer case.
They communicate with theThey communicate with the
main part of the computermain part of the computer
usingusing portsports..

HardwareHardware
In addition to receiving information directly fromIn addition to receiving information directly from
human users via input devices, computers canhuman users via input devices, computers can
receive information from other computers. Thisreceive information from other computers. This
is done via a network, e.g. the Internet.is done via a network, e.g. the Internet.
Network information can come to the computersNetwork information can come to the computers
through:through:
 Hard linesHard lines (standard telephone line)(standard telephone line)
 WirelessWireless (via radio signals)(via radio signals)

HardwareHardware
Computers have theComputers have the
ability to storeability to store
information:information:
 Floppy DisksFloppy Disks
 Compact DiscsCompact Discs
(CDs)(CDs)
 Digital Video DiscsDigital Video Discs
(DVDs)(DVDs)

Inside your ComputerInside your Computer
TheThe systems boardsystems board,,
oror motherboardmotherboard, is, is
the brain of thethe brain of the
computer. Thecomputer. The
motherboardmotherboard
contains a series ofcontains a series of
micro chips that aremicro chips that are
connected togetherconnected together
by circuitry.by circuitry.

Circuits, like wires or cables, transmitCircuits, like wires or cables, transmit
electrical signals containing binaryelectrical signals containing binary
data between the various microchips.data between the various microchips.
TheThe microchipsmicrochips in the computer canin the computer can
detect the presence or absence ofdetect the presence or absence of
electronic impulses.electronic impulses.

The Motherboard contains three typesThe Motherboard contains three types
of memory chips:of memory chips:
 TheThe Central Processing Unit (CPU)Central Processing Unit (CPU)
 TheThe Read-only Memory (ROM)Read-only Memory (ROM)
 TheThe Random Access MemoryRandom Access Memory
(RAM)(RAM)
Inside The ComputerInside The Computer

The CPU has three core sets ofThe CPU has three core sets of
instructions that it carries out:instructions that it carries out:
 Mathematical computations (addition,Mathematical computations (addition,
subtraction, division);subtraction, division);
 Moving data or information from oneMoving data or information from one
memory location to another; and,memory location to another; and,
 Making decisions and moving to aMaking decisions and moving to a
different set of instructions based upondifferent set of instructions based upon
those decisions.those decisions.

Random Access Memory (RAM)Random Access Memory (RAM)
chips contain information onlychips contain information only
when your computer is on. Whenwhen your computer is on. When
you turn off the computer, theyou turn off the computer, the
memory in the RAM disappears.memory in the RAM disappears.
Also known as
Volatile storage!

 Read Only Memory (ROM) Contains the basicRead Only Memory (ROM) Contains the basic
set of instructions that are required to start theset of instructions that are required to start the
computer.computer.
 Memory was installed during theMemory was installed during the
manufacturing process.manufacturing process.
 ROM (BIOS instructions) is a permanent partROM (BIOS instructions) is a permanent part
of the chip.of the chip.
Also known as
Non- Volatile storage!

 The Motherboard contains…..The Motherboard contains…..
 AA Complementary Metal Oxide Semi-Complementary Metal Oxide Semi-
conductor (CMOS)conductor (CMOS) configuration chip.configuration chip.
 A system clock.A system clock.
 Expansions slots.Expansions slots.
 RAMRAM memory.memory.

 The CMOS Chip:The CMOS Chip:
 Responsible for remembering whatResponsible for remembering what
hardware is in your computer.hardware is in your computer.
 Necessary for your computer to initiallyNecessary for your computer to initially
organize itself. If you added a new drive,organize itself. If you added a new drive,
card, or peripheral device, your CMOScard, or peripheral device, your CMOS
information would change.information would change.
 Volatile (information can be lost) so it has itsVolatile (information can be lost) so it has its
own battery with constant powerown battery with constant power

 Random Access Memory (RAM)Random Access Memory (RAM)
………….………….
 Contains information your computer isContains information your computer is
working with now (What is on the screen).working with now (What is on the screen).
 Has to be limited in the amount ofHas to be limited in the amount of
information it can contain.information it can contain.
 Once you are finished using the RAM andOnce you are finished using the RAM and
move on to another project, what was inmove on to another project, what was in
RAM is dumped.RAM is dumped.

Cache MemoryCache Memory contains memorycontains memory
your computer anticipates youyour computer anticipates you
might need, similar to the humanmight need, similar to the human
brain. It makes assumptions aboutbrain. It makes assumptions about
what information you might needwhat information you might need
based on certain programming.based on certain programming.

 A BUS Contains theA BUS Contains the
electrical pathways andelectrical pathways and
directions for use of thosedirections for use of those
pathways that thepathways that the
information uses whileinformation uses while
inside a computer.inside a computer.
 The small metal tracings inThe small metal tracings in
the circuit board take thethe circuit board take the
place of wires to conductplace of wires to conduct
electricity.electricity.
 The bus is these traces andThe bus is these traces and
the instructions for theirthe instructions for their
use.use.

CMOS Chips Continually hold theCMOS Chips Continually hold the
information on the configuration of yourinformation on the configuration of your
computer. When you turn on the computer,computer. When you turn on the computer,
the startup process is called athe startup process is called a bootingbooting..
When a computer is booted from the power-When a computer is booted from the power-
off condition, it is called a “off condition, it is called a “hard boothard boot.” If.” If
you push the reset button, you areyou push the reset button, you are
performing a “performing a “soft boot.”soft boot.”

TheThe Random Access Memory (ROM)Random Access Memory (ROM) containscontains
a set of permanent instructions known as thea set of permanent instructions known as the
basic input/output system (BIOS).basic input/output system (BIOS). SometimesSometimes
referred to as thereferred to as the ROM BIOSROM BIOS or Flash BIOSor Flash BIOS..
ROM chips are a hybrid of both hardware andROM chips are a hybrid of both hardware and
software. It is a physical component withsoftware. It is a physical component with
embedded software. ROM chips areembedded software. ROM chips are
sometimes referred to assometimes referred to as firmwarefirmware..

Information on the Motherboard, exceptInformation on the Motherboard, except
the ROM chip, isthe ROM chip, is volatilevolatile..
Long term or secondaryLong term or secondary
storage are non-volatile:storage are non-volatile:
 Hard disks;Hard disks;
 Zip disks;Zip disks;
 Floppy disks; CassetteFloppy disks; Cassette
tapes;tapes;
 CD-ROMs; and,CD-ROMs; and,

DVDs.DVDs.
Inside Your Computer

SoftwareSoftware
 Instructions that tellInstructions that tell
hardware what tohardware what to
do; or,do; or,
 A set of instructionsA set of instructions
written in awritten in a
language that thelanguage that the
computer cancomputer can
understand.understand.
Two broad classificationsTwo broad classifications
of software:of software:
 Operating SystemsOperating Systems (also(also
called platform)called platform)
 ApplicationsApplications

Operating SystemsOperating Systems
 Tells the computerTells the computer
what to do.what to do.
 The computerThe computer
software that controlssoftware that controls
and coordinates theand coordinates the
interaction among theinteraction among the
hardware elementshardware elements
and between theand between the
hardware and thehardware and the
application programs.application programs.
The operating
system is the
computer’s
traffic cop.

After your computer has booted and CMOSAfter your computer has booted and CMOS
hands your computer over to the operatinghands your computer over to the operating
system the operating system has twosystem the operating system has two
primary functions:primary functions:
 Managing the hardware and software.Managing the hardware and software.
 It provides application program interfaceIt provides application program interface
(API).(API).
Operating SystemsOperating Systems

Disc Operating SystemDisc Operating System
DOSDOS is probably the most common operating system.is probably the most common operating system.
Users interface with a DOS in one of three ways:Users interface with a DOS in one of three ways:
 A command driven interface;A command driven interface;
 A menu-driven interface; or,A menu-driven interface; or,
 An icon-driven interface.An icon-driven interface.
MostMost policepolice employees work with an icon-drivenemployees work with an icon-driven
interface that is also called ainterface that is also called a graphical usergraphical user
interface (GUI).interface (GUI).

ApplicationsApplications
ApplicationsApplications softwaresoftware
allows the user toallows the user to
work with informationwork with information
in the computer.in the computer.
Applications areApplications are
specific programs thatspecific programs that
allow the user to doallow the user to do
specific tasks such asspecific tasks such as
word processing.word processing.

DatabasesDatabases
A collection of organized informationA collection of organized information
that is centrally located and designedthat is centrally located and designed
to meet the needs of users. There areto meet the needs of users. There are
two classifications of databases:two classifications of databases:
 Flat fileFlat file
 Relational DatabaseRelational Database

Forced Choice FormatsForced Choice Formats
Many state and localMany state and local policepolice
agencies use software that allowsagencies use software that allows
them to configure data entries tothem to configure data entries to
match their specific datamatch their specific data
dictionary.dictionary.
Through the use ofThrough the use of forced-choiceforced-choice
formatsformats, GUI software restricts, GUI software restricts
data entries to previouslydata entries to previously
determined attributes, propertiesdetermined attributes, properties
or characteristics.or characteristics.
Screen capture provided by Crimestar Corporation

Useful TermsUseful Terms
 Multi-mediaMulti-media is the different forms of media beingis the different forms of media being
used by any particular application.used by any particular application.
 Multimedia applications can include graphics, animation, sound, andMultimedia applications can include graphics, animation, sound, and
video elementsvideo elements
 AA scalablescalable system can be adapted andsystem can be adapted and
expanded to meet increased needs.expanded to meet increased needs.
 Most legacy systems areMost legacy systems are proprietaryproprietary..
 The system manufacturer (either hardware, software,The system manufacturer (either hardware, software,
or both) will not reveal the systems specifications soor both) will not reveal the systems specifications so
that other firms may not duplicate the product.that other firms may not duplicate the product.
 Also known as aAlso known as a closed architectureclosed architecture..

Copyright 2005 - 2009: Hi Tech Criminal Justice, Raymond E. Foster
Police TechnologyPolice Technology
DiscussDiscuss criminal justicecriminal justice issuesissues
www.criminaljustice-online.comwww.criminaljustice-online.com

Computer Basics

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