Computer Basics

Copyright 2005 - 2009: Hi Tech Criminal Justice, Raymond E. Foster

Police Technology Police Technology Chapter TwoChapter Two

ComputerComputer Basics Basics


Learning ObjectivesLearning Objectives Understand the basic hardware and Understand the basic hardware and

software components of a software components of a Desk Top Desk Top Personal Computer (PC).Personal Computer (PC).

The difference between The difference between Operating Operating SystemsSystems and and Applications softwareApplications software..

The difference between and The difference between and Flat Flat FileFile and and Relational DatabaseRelational Database


Binary Number SystemBinary Number SystemA mathematical counting schemeA mathematical counting scheme

that has only two digits – zero that 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 Today’s computers use this off/on scheme to this off/on scheme to represent the represent the binary binary digitsdigits, commonly , commonly referred to as referred to as bitsbits, 1 and , 1 and 0. 0.


It is simple for computers to translate It is simple for computers to translate binary binary

digits into a sixteen digit-based code called digits into a sixteen digit-based code called

hexadecimalhexadecimal. This coding system is a . This coding system is a

compromise between our abilities and the compromise between our abilities and the

computer that allows us to computer that allows us to interface.interface.

Binary Number SystemBinary Number System


ASCIIASCIIThe standard computer code configuration The standard computer code configuration

that works with computer bits is called the that works with computer bits is called the

American Standard Code for Information American Standard Code for Information

Interchange (ASCII).Interchange (ASCII).

A byte is eight bits, or a series of eight ones

and zeros.

Binary digits

ByteASCII

Words you can read!


Interface Means to InteractInterface Means to Interact

User interface is User interface is how we interact how we interact with the with the computer, e.g. computer, e.g. the keyboard and the keyboard and mouse are user mouse are user interface interface inputsinputs and the monitor is and the monitor is the computer’s the computer’s user interface user interface outputoutput


A computer system can considered as A computer system can considered as

three broad categories of components: three broad categories of components: Hardware Hardware SoftwareSoftware FirmwareFirmware

Your Computer as a SystemYour Computer as a System


Your Computer as a System Your Computer as a System

The user is a human being.

The input devices are the computer keyboard, mouse, and microphone.

The output devices are themonitor, speakers, printer, and various storage media.


HardwareHardware

Input/output devices are Input/output devices are

referred to as referred to as peripheral peripheral

devicesdevices. Think of a. Think of a

peripheral device as any peripheral device as any

device device notnot inside the inside the

computer case. computer case.

They communicate with They communicate with the the

main part of the computer main part of the computer using using portsports. .


HardwareHardware

In addition to receiving information directly from In addition to receiving information directly from human users via input devices, computers can human users via input devices, computers can receive information from other computers. This receive 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 computersthrough:through: Hard linesHard lines (standard telephone line)(standard telephone line) Wireless Wireless (via radio signals)(via radio signals)


HardwareHardware

Computers have the Computers have the

ability to storeability to store

information: information: Floppy DisksFloppy Disks Compact Discs Compact Discs

(CDs) (CDs) Digital Video Digital Video

Discs (DVDs)Discs (DVDs)


Inside your Computer Inside your Computer

The The systems boardsystems board,, or or motherboardmotherboard, is , is the brain of the the brain of the computer. The computer. The motherboard motherboard contains a series of contains a series of micro chips that micro chips that are connected are connected together by together by circuitry. circuitry.


Inside your ComputerInside your Computer

Circuits, like wires or cables, Circuits, like wires or cables, transmit electrical signals transmit electrical signals containing binary data between containing binary data between the various microchips.the various microchips.

The The microchipsmicrochips in the computer in the computer can detect the presence or can detect the presence or absence of electronic impulses. absence of electronic impulses.


The Motherboard contains three typesThe Motherboard contains three types

of memory chips: of memory chips: The The Central Processing Unit (CPU)Central Processing Unit (CPU) The The Read-only Memory (ROM)Read-only Memory (ROM) The The Random Access Memory (RAM)Random Access Memory (RAM)

Inside The ComputerInside The Computer


The CPU has three core sets of The CPU has three core sets of

instructions that it carries out: instructions that it carries out: Mathematical computations Mathematical computations

(addition, subtraction, division); (addition, subtraction, division); Moving data or information from one Moving data or information from one

memory location to another; and, memory location to another; and, Making decisions and moving to a Making decisions and moving to a

different set of instructions based different set of instructions based upon those decisions.upon those decisions.




Random Access Memory (RAM)Random Access Memory (RAM) chips contain information only chips contain information only when your computer is on. when your computer is on. When you turn off the When you turn off the computer, the memory in the computer, the memory in the RAM disappears. RAM disappears.

Also known asVolatile storage!



Read Only Memory (ROM) Contains the Read Only Memory (ROM) Contains the basic set of instructions that are required basic set of instructions that are required to start the computer. to start the computer.

Memory was installed during the Memory was installed during the manufacturing process. manufacturing process.

ROM (BIOS instructions) is a permanent ROM (BIOS instructions) is a permanent part of the chip.part of the chip.

Also known asNon- Volatile storage!



The Motherboard contains…..The Motherboard contains….. A A Complementary Metal Oxide Complementary Metal Oxide

Semi-conductor (CMOS)Semi-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 what Responsible for remembering what

hardware is in your computer. hardware is in your computer. Necessary for your computer to initially Necessary for your computer to initially

organize itself. If you added a new organize itself. If you added a new drive, card, or peripheral device, your drive, card, or peripheral device, your CMOS information would change. CMOS information would change.

Volatile (information can be lost) so it Volatile (information can be lost) so it has its own battery with constant has its own battery with constant powerpower



Random Access Memory (RAM)Random Access Memory (RAM) ………….………….

Contains information your computer is Contains information your computer is working with now (What is on the working with now (What is on the screen). screen).

Has to be limited in the amount of Has to be limited in the amount of information it can contain. information it can contain.

Once you are finished using the RAM Once you are finished using the RAM and move on to another project, what and move on to another project, what was in RAM is dumped. was in RAM is dumped.



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


Inside your ComputerInside your Computer A BUS Contains the A BUS Contains the

electrical pathways and electrical pathways and directions for use of directions for use of those pathways that the those pathways that the information uses while information uses while inside a computer. inside a computer.

The small metal tracings The small metal tracings in the circuit board take in the circuit board take the place of wires to the place of wires to conduct electricity.conduct electricity.

The bus is these traces The bus is these traces and the instructions for and the instructions for their use. their use.



CMOS Chips Continually hold theCMOS Chips Continually hold theinformation on the configuration of your information on the configuration of your computer. When you turn on the computer, computer. When you turn on the computer, the startup process is called a the 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 are you push the reset button, you are performing a “performing a “soft boot.”soft boot.”


The The Random Access Memory (ROM)Random Access Memory (ROM) contains a set of permanent instructions contains a set of permanent instructions known as the known as the basic input/output system basic input/output system (BIOS).(BIOS). Sometimes referred to as the Sometimes referred to as the ROM ROM BIOSBIOS or Flash BIOS or Flash BIOS. .

ROM chips are a hybrid of both hardware ROM chips are a hybrid of both hardware and software. It is a physical component and software. It is a physical component with embedded software. ROM chips are with embedded software. ROM chips are sometimes referred to as sometimes referred to as firmwarefirmware. .



Information on the Motherboard, except Information on the Motherboard, except the ROM chip, is the ROM chip, is volatilevolatile..

Long term or secondary Long term or secondary storage are non-volatile: storage are non-volatile: Hard disks;Hard disks; Zip disks;Zip disks; Floppy disks; Floppy disks;

Cassette tapes;Cassette tapes; CD-ROMs; and, CD-ROMs; and, DVDs.DVDs.

Inside Your Computer


Software Software

Instructions that Instructions that tell hardware tell hardware what to do; or, what to do; or,

A set of A set of instructions instructions written in a written in a language that the language that the computer can computer can understand. understand.

Two broad classificationsTwo broad classifications

of software: of software:

Operating SystemsOperating Systems (also called platform)(also called platform)

ApplicationsApplications


Operating SystemsOperating Systems

Tells the computer Tells the computer what to do. what to do.

The computer The computer software that controls software that controls and coordinates the and coordinates the interaction among the interaction among the hardware elements hardware elements and between the and between the hardware and the hardware and the application programs.application programs.

The operatingsystem is thecomputer’s traffic cop.


After your computer has booted and CMOS After your computer has booted and CMOS

hands your computer over to the hands your computer over to the operating operating

system the operating system has two system the operating system has two

primary functions: primary functions: Managing the hardware and software.Managing the hardware and software. It provides application program It provides application program

interface (API).interface (API).

Operating SystemsOperating Systems


Disc Operating SystemDisc Operating System

DOSDOS is probably the most common operating is probably the most common operating system. 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.

Most Most policepolice employees work with an icon-driven employees work with an icon-driveninterface that is also called a interface that is also called a graphical user graphical user interface (GUI).interface (GUI).


ApplicationsApplications

ApplicationsApplications software allows software allows the user to work the user to work with information with information in the computer. in the computer. Applications are Applications are specific programs specific programs that allow the that allow the user to do user to do specific tasks specific tasks such as word such as word processing. processing.


Databases Databases

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 local Many state and local policepolice agencies use software that agencies use software that

allows allows them to configure data entries them to configure data entries

to to match their specific data match their specific data dictionary. dictionary.

Through the use of Through the use of forced-forced-choice choice

formatsformats, GUI software restricts , GUI software restricts data entries to previously data entries to previously determined attributes, determined attributes,

properties properties or characteristics. or characteristics.

Screen capture provided by Crimestar Corporation


Useful TermsUseful Terms

Multi-mediaMulti-media is the different forms of media is the different forms of media being used by any particular application.being used by any particular application. Multimedia applications can include graphics, animation, Multimedia applications can include graphics, animation,

sound, and video elementssound, and video elements

A A scalablescalable system can be adapted and system can be adapted and expanded to meet increased needs. expanded to meet increased needs.

Most legacy systems are Most legacy systems are proprietaryproprietary. . The system manufacturer (either hardware, The system manufacturer (either hardware,

software, or both) will not reveal the systems software, or both) will not reveal the systems specifications so that other firms may not specifications so that other firms may not duplicate the product. duplicate the product.

Also known as a Also known as a closed architectureclosed architecture. .


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