unit 1_introduction computers and it_fund of it

8/10/2019 Unit 1_Introduction Computers and IT_Fund of IT

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Introduction to Computers and

Information Technology

Unit 1


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Information SystemsWhat is an Information System?

A set of interrelated components that collect (or retrieve), process, store and

distribute information to support decision making, coordination and control in anorganization.

Help managers and workers analyze problems, visualize complex subjects and

create new products.

Examples: ATMs, airline reservation systems, course reservation systems.

Data

The collection of unprocessed items such as text, numbers, image, audio and videofor input in the computer.

Information

Processed data (output) that conveys a meaning and is useful to people.

Desired characteristics of information

Accurate, clear, timely, complete yet concise

Receiver has confidence in it

Appropriate channel, given to the right person, should not be excessive

Cost effective

Must have a purpose and relevant to the purpose (user related)

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Components of an Information System

Information Processing Cycle

A series of input, processing, output and storage activities performed by the computer

Input -Data are collected and entered into computer.

Processing -Data are manipulated into information using mathematical, statistical,and other tools.

Output - Information is displayed or presented

Feedback -This is an output that help the organization to evaluate or correct the inputstage.

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Introduction to Computer

ComputerA electronic device, operating under the control of instructions stored in

its own memory.

A computer can accept data, process the data according to specified rules, produceresults and store the results for future use.

A computer process data into information.

Data The collection of unprocessed items, which include text, numbers, images,

audio and video.

InformationConveys meaning and is useful to people.

Computer Systems - A set of components that interact to achieve a common goal.The purpose, therefore, of a computer system is to use all its working components to

produce quality information.

Computer System ComponentsA computer contains many electric, electronic

and mechanical components known as hardware, (see Fig. 1.1).

Input DevicesAllows you to enter data and instruction into the computer.

Output DevicesConvey information to one or more people. System Unit Contains the electronic components of the computer that is used to

process data.

Storage DevicesHolds data, instructions and information for future use.

Information Technology - information technology is the use of computers and

software to manage information.

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Introduction to Computer, (Cont)


printer(output device)

memorycards

(storagedevice)

cardreader/writer

(storage device)

external harddisk

(storage device)

modem

(communications device)

monitor(output device)


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Introduction to Computer, (Cont) Communication DevicesEnable the computer to transmit and receive

data, instructions, and information to and from one or more computers or

mobile devices Information Processing CycleA series of input, processing, output and

storage activities.

Unit of Storage .

Figure 1. 2 Unit of Storage


Term Abbreviation Number of bytes Exact Value

Kilobyte KB 1 thousand 210or 1, 024

Megabyte MB 1 million 220or 1, 048, 576

Gigabyte GB 1 billion 230or 1, 073, 741, 824

Terabyte TB 1 trillion 240or 1, 099, 511, 627, 776

Petabyte PB 1 quadrillion 250or 1, 125, 899, 906, 842, 624

Exabyte EB 1 quintillion 260or 1, 152, 921, 504, 606, 846, 976


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Components of a Computer SystemInput Devices:

An input device is any peripheral device that allows one to enter data or

instructions into a computer, (see Fig 1.3). Five widely input devices are keyboard, mouse, microphone, scanner, web

cam.

Other input devices that are used in todays society may include, Light-pen,

Optical Character Recognition (OCR), Magnetic-Ink Character Recognition

(MICR), and Joy Sticks.Forms used for Input:

A tu rnaround documentis a machine readable document that has some

information printed on it by a computer.

A turn around document is one that is fed to the computer for analysis. This

source data entry eliminates the need for transcriptions, thus eliminating

errors to be made.

Examples: shaded answer sheets, utility bills (OCR), and bar codes, U.P.C.,

encoded cheques, among others.



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Components of a Computer System, (Cont)


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Components of a Computer System, (Cont)Output Devices:

An output device is any peripheral that conveys information to one or more

individuals, (see Fig 1.4). We consider data that has been processed into a useable form as output.

Computer systems can generate several types of output, depending on the

hardware and software being usedit may be printed, seen, or heard.

Popular output devices include: printer, speaker, and monitor.

Output Highlights: Output is the process of translating data that are in machine-readable form

to a form that human being can understand.

Thus, the output device is the hardware that enables this communication

with human and computer.

Output can be divided into output that is read and used by persons, as wellas those that hold data for temporary or permanent storage.

Hard copyRefers to output that can be held (tangible); usually refers to output

on paper, in a more permanent form.

Soft copyRefers to a more transient form of output (intangible); usually it refers

to output that are on screen or heard.



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Components of a Computer System, (Cont)Output Highlights:

As noted, output may be in the form of a hardcopy and softcopy. The printer

is used to produce this type of output. However due to the respectiveindustries that require hardcopy output, there are various types of printers.

Thus two types of printing mechanisms allow printers to be either impact

printers and non-impact printers

Impact printersRefers to printers that strike the papers to leave an

impression of the information desired. Non-impact printersRefers to printers that use additional technology,

such as laser or thermal heating, to give impressions of information as

output.

Consequently, there are line, characters, and page printers.

Character printersPrint one character at a time; some character printer

prints from left to right and right to left which speeds up the printing.

Line printersUse special mechanism to print one line at a time; some will

print typically a range of hundreds to thousands of lines per minute.

Page printersUse to print one page at a time; typically, these printers

produce thousands of pages per minute.



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Components of a Computer System, (Cont)Output Highlights:

Monitor- The monitor is the most common form of softcopy output device.

The quality of an image is dependent on the resolution that is given by themonitor (a measure of the number of elements of a picture, or pixel on a

monitor).

Pixel- A pixel is the smallest increment of display that can be controlled by

an individual.

The more pixel the clearer and sharper the image on screendot per inch. Other factors that affect the monitor is the refresh rate.

Refresh Rate - the number of times a screen is scanned to maintain an

image.

There are two kinds of monitors for viewing: cathode-ray tube (CRT) and

the flat-panel display (liquid crystal display).



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Components of a Computer System, (Cont)Processing:

The processor is the electronic component that interprets and carries out

instructions to operate the computer system (which resides on themotherboard), (see Fig 1.5).

The central processing unit is that part of the computer that decodes and

executes instructions; it is comprised of the arithmetic/logical unit as well as

a control unit.

In microprocessors, the CPU is combined on a single chip; where as inlarge computers there is need for more than one CPUs due to the

processing requirements.

As such large computers will implement parallel processingdividing a task

among other processors, allowing simulations to for example, to be

performed quickly. Thus, a microcomputer will use a single processor to do

serial processing. Access time measures the amount of time taken by a storage device to

retrieve an item on storage media as well as deliver item from memory to

processor.

Transfer rate is the speed at which data, instructions and information move

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Components of a Computer System, (Cont)The Control Unit:

The control unit is a component of the processor that directs and

coordinates most of the operations in the computer. It interprets each instruction issued by a program and then initiates the

appropriate action to carry out the instructions.

The types of internal component that the control unit directs include

arithmetic logic unit (ALU), registers and buses.

Arithmetic Logic Unit (ALU) ALU is another component of the processor that performs arithmetic,

comparison, and other operations.

Arithmetic operations include basic calculations such as addition,

subtraction, multiplication and division.

Comparing operations involve comparing one data to another to determine

greater than, less than or equal to.

Machine Cycle:

For every instruction, a processor repeats a set of four basic instruction

which is comprised or called a machine cycle.



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Components of a Computer System, (Cont)Fetching

The process of obtaining a program instruction or data item from memory.

Example - A student enter a maths problem into the memory of thecomputer

Step 1 - The CU fetches the math problems instructions and data from

memory.

Decoding

The process of translating the instructions into signals the computer canexecute

Step 2The CU decodes the instructions and sends the instructions to the

ALU.

Executing

The process of carrying out the commands Step 3The ALU performs calculations on the data

Write back (Storing)

This process writes the result to memory

Step 4The results of math are stored in memory.



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Components of a Computer System, (Cont)Registers

The processor contains a small, high-speed storage locations, called

registers, that temporarily hold data and instructions.The System Clock

The processor relies on a small quartz crystal circuit called the system clock

to control the timing of all computer operations.

Clock speedthe pace of the system clock is measured by the number of

tick per second. Current PC have clock speed in the gigahertz (GHz) range.

The faster the clock speed the more instructions the processor can execute

per second.



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Components of a Computer System, (Cont)Processing:

The control unit is main controller of data flowing within as well as out of the

computer system; its effectiveness is based on a synchronization of tasks. That is, controlling the occurrences of events through the use of electrical

timing signals that are given by the system clock.

Microprocessor

These are processors that are developed through the use of semiconductor

technology. Such technology are made up of transistors that form electrical circuits that

allow transmission of electricity.

This is ideal since data representation is zero or one.

Thus, a complete electronic semiconductor circuit that is etched onto a

silicon gives an integrated circuit (microchip), which is then placed on a

motherboard.



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Below are some of the leading processor chip manufacturers:

Chip Name Manufacturer Clock Speed

Itanium 2 Intel 1 GHz and up

Xeon Intel 1.4 to 2.8 GHz

Pentium 4 Intel 1.4 GHz to 3.06 GHz

Opteron AMD 2 to 2.4 GHz

Athlon AMD 500 MHz to 1.4 GHz

Duron AMD 600 MHz to 1.4 GHz

PowerPC Motorola 50 MHz to 1.25 GHz

68040 Motorola 25 to 40 MHz

68030 Motorola 16 to 50 MHz

To avoid burnt chips processors are not only coupled with fans, but

also heat sinks (heat pipes are used in laptops).



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Components of a Computer System, (Cont)Storage:

Storage components hold data, instruction, as well as information for future

use; these items are kept on storage media (which are housed within thesystem unit).

Storage, or memory, consists of electrical components that store instructions and

data waiting to be executed by the processor, as well as their results.

The computer system stores three categories of items: OS and software;

application programs; and data being processed.

Computer memory consist of two types of memory: volatile and non-volatile. An

example of volatile memory is RAM, while ROM is and example of non-volatile

memory.

It is also important to note at this point, that when information in memory is being

accessed it can be retrieved sequentially or directly.

Also the terms storage medium is singular, while storage media is plural; andstorage devices are technology to get/store data.

The term capacity is commonly used to refer to the number of bytes a storage

medium can hold.

Additional terms related to memory is access time and transfer rate.



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Components of a Computer System, (Cont)Storage Volatile and Non-Volatile:

The amount of primary (main) memory within a computer is dependent on

the software packages to be used. Consequently, there are various types of volatile storage: RAM, DRAM,

SDRAM, DDR SDRAM, RDRAM, and SRAM; cache and buffer, among

others.

The non-volatilestorage affords the computer system the capability of

letting data survive without power.

This type of memory are classed as either secondary or tertiary storage.

Additionally, the memory capacity is dependent on users or organizational

needs.

Some types of non-volatile storage include: ROM, PROM, EEPROM, hard

disk, flash drive, CD-ROM, DVD-ROM, CD-RW, Zip Disks, and Blu-Ray

Discs, among others.



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Components of a Computer System, (Cont)Volatile :

Primary (main) memory consists of chips that can only store information

when electricity is present; within which time its contents can change. Two basic types of RAM chips exit: dynamic RAM and static RAM .

Dynamic RAM: DRAM chips must re-energize else their contents are lost;

the synchronous DRAM are faster as their contents are coordinated to the

systems clock; double data rate SDRAM refresh their contents twice each

clock cycle;

Static RAM: SRAM chips are notably more reliable, as their contents are

not refreshed as often as DRAM chips; however, they are expensive.

The following memory storage now relate to hardware: cache and buffers.

Cache memory: aids the processing speed of computers because it stores

frequent instructions and data. Most computers use L1 and L2 cache

(smaller to larger).

Fetching of data or instructions will occur from slower storage media, if not

present in cache.

Buffer: is a segment of storage in which items are placed while waiting to

be transferred from and input device, or to an output device.



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Components of a Computer System, (Cont)Non-Volatile :

We now turn our attention to the storage media that are non-volatile; as

expected they are much slower that main memory, however their capacityand ability to store for future use complements its speed.

Hard Disk: fixed/external disk, store majority of computers information;

they are enclosed in a module. A hard disk has multiple read/write heads on

an access arm that moves across the magnetic surface (platters), that store

information ,(see Fig 1.7).

The read/write head access/store data based on an address that is given

through the disks track and sector number.

Advantages- Considered the fastest secondary storage media for

information retrieval; capable of holding large amount of information.

Disadvantages- Expensive and least portable.



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Magnetic Tape: This media has a continuous reel of recording surface,

where the reel is a magnetized surface on which data is stored. Magnetic surface of magnetic tapes are found on debit cards, but are known

as strips.

The data on a magnetic tape is stored in parallel tracks; each surface has

an extra track that is used to store aparity bit (used to ensure the integrity

of the data that is being read or written on the frame).

Advantages- It is least expensive; its fairly safe to use; and has space for

backing up large amount of information.

Disadvantages - The access of files are done sequentially, and thus

retrieving information is slow.



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Read-Only Memory: These memory chips store data and instructions

permanently ( cannot be modified); many such chips are found in hardwaredevices (firmware).

A programmable read-only memory (PROM), enables microcode

instructions to be written to chips by programmers.

On the other hand, a electrically erasable programmable read-only memory

(EEPROM) enables removal of microcode with electric signals

Advantages- Instructions and data are not lost when power ceases;

instructions are either unchangeable or require special operation to change

them.

Disadvantages- If instructions are incorrect, or the data on chips need to

be updated, they are useless; some chips limited with respect to the times

data can be re-written.



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Optical Disc: With respect to portability, this media can store more data

than some magnetic disks. There exists three types of discs: ROM, Recordable, and Re-Writeable.

Optical discs use laser technology to both store and read data.

It uses pulses for the 1's and non-pulses for the 0's to record data on the

surface of the disc, as microscopically small pits and lands. Some optical

discs are: Compact Disc Read-Only Memory (CD-ROM), Compact DiscRecordable (CD-R), Compact Disc Re-Writable (CD-RW), Digital Versatile

Discs (DVD), and Blu-Ray Discs.

Advantages- Some optical discs store massive data; facilitates portability;

good means of distributing software; some discs facility reuse.

Disadvantages- The contents of some discs can not be changed; must

have respective optical drives to use certain discs.



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Flash Memory: The contents of such technology are erased similar to

EEPROM. It has a grid of columns and rows with a cell that has two transistors at each

intersection: a floating gate and a control gate.

An electrical charge, usually 10 to 13 volts, is applied to the floating gate. If

the flow through the gate is greater than the charge it has a value of 1,

else the value changes to 0.

Some examples are: the computer's BIOS chip; Compact Flash, Smart

Media and Memory Stick (found in digital cameras); and Memory cards for

video game consoles.

Advantage- Good means for easy and fast information storage.

Disadvantage- Limited with respect to the times data can be re-written.



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Components of a Computer System, (Cont)Storage Media :

Also called secondary storage, is the physical material on which the

computer keeps data, instructions, and information. Examples - hard disk, solid state drives, memory cards, USB flash drives,

optical discs, smart card magnetic stripe cards and microfilm

Optical Disc: With respect to portability, this media can store more data

than some magnetic disks.

There exists three types of discs: ROM, Recordable, and Re-Writeable. Optical discs use laser technology to both store and read data.

It uses pulses for the 1's and non-pulses for the 0's to record data on the

surface of the disc, as microscopically small pits and lands. Some optical

discs are: Compact Disc Read-Only Memory (CD-ROM), Compact Disc

Recordable (CD-R), Compact Disc Re-Writable (CD-RW), Digital Versatile

Discs (DVD), and Blu-Ray Discs.

Advantages- Some optical discs store massive data; facilitates portability;

good means of distributing software; some discs facility reuse.

Disadvantages- The contents of some discs can not be changed; must

have respective optical drives to use certain discs.



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Components of a Computer System, (Cont)Communication devices:

A communication device is a hardware component that enables a computer to

send (transmit) and receive data, instructions, and information to and from one ormore computers or mobile devices.

A widely used communications device is a modem.

Communications occur over cables, telephone lines, cellular radio networks,

satellites, and other transmission media.

Some transmission media, such as satellites and cellular radio networks, are

wireless, which means they have no physical lines or wires.



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Use of the Computer

The common uses of computer may then include: entertainment, classes for

learning, banking and investments, shopping, research for information, and

communication, among others. Benefits from using computers are possible because computers have the

advantages of speed, reliability, consistency, storage, and communications.

Advantages of Using Computers:

Speed: When data, instructions, and information flow along electronic

circuits in a computer, they travel at incredibly fast speeds. Many computers process billions or trillions of operations in a single second.

Processing involves computing (adding, subtracting, etc.), sorting (e.g.,

alphabetizing), organizing, displaying images, recording audio, playing

music, and showing a movie or video.

Reliability: The electronic components in modern computers are

dependable and reliable because they rarely break or fail.

Consistency: Given the same input and processes, a computer will

produce the same results - consistently.

A computing phrase known as garbage in, garbage outpoints out that the

accuracy of a computer's output depends on the accuracy of the input.



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Use of the Computer, (Cont) Storage:A computer can transfer data quickly from storage to memory,

process it, and then store it again for future use.

Many computers store enormous amounts of data and make this dataavailable for processing anytime it is needed.

Communications: Most computers today can communicate with other

computers, often wirelessly.

Computers with this capability can share any of the four information

processing cycle operations - input, process, output, and storage.



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Use of the Computer, (Cont)Disadvantages of Using Computers:

Some disadvantages of computers relate to health risks, the violation of

privacy, public safety, the impact on the labor force, and the impact on theenvironment.

Health Risks: Prolonged or improper computer use can lead to injuries or

disorders of the hands, wrists, elbows, eyes, neck, and back.

Computer users can protect themselves from these health risks through

proper workplace design, good posture while at the computer, and

appropriately spaced work breaks.

Two behavioral health risks are computer addiction and technology

overload.

Computer addiction occurs when someone becomes obsessed with using a

computer.

Individuals suffering from technology overload feel distressed whendeprived of computers and mobile devices.

Once recognized, both computer addiction and technology overload are

treatable disorders.



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Use of the Computer, (Cont) Violation of Privacy: Nearly every life event is stored in a computer

somewhere in medical records, credit reports, tax records, etc.

In many instances, where personal and confidential records were notprotected properly, individuals have found their privacy violated and

identities stolen.

Public Safety:Adults, teens, and children around the world are using

computers to share publicly their photos, videos, journals, music, and other

personal information.

Some of these unsuspecting, innocent computer users have fallen victim to

crimes committed by dangerous strangers.

Protect yourself and your dependents from these criminals by being

cautious in e-mail messages and on Web sites.

For example, do not share information that would allow others to identify or

locate you and do not disclose identification numbers, passwords, or otherpersonal security details.

Impact on Labor Force:Although computers have improved productivity in

many ways and created an entire industry with hundreds of thousands of

new jobs, the skills of millions of employees have been replaced bycomputers.



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Use of the Computer, (Cont) Computers impact on the labor force makes it crucial that workers keep

their education up-to-date.

A separate impact on the labor force is that some companies areoutsourcing jobs to foreign countries instead of keeping their homeland

labor force employed.

Impact on Environment: Computer manufacturing processes and

computer waste are depleting natural resources and polluting the

environment.

When computers are discarded in landfills, they release toxic materials and

potentially dangerous levels of lead, mercury, and flame retardants.

Green computing involves reducing the electricity consumed and

environmental waste generated when using a computer. Strategies that

support green computing include recycling, regulating manufacturing

processes, extending the life of computers, and immediately donating orproperly disposing of replaced computers.

When you purchase a new computer, some retailers offer to dispose of your

old computer properly.



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Categories of Computers Computer experts typically classify computers in seven categories: personal

computers (desktop), mobile computers and mobile devices, game

consoles, servers, mainframes, supercomputers and embedded computers.

A computers size, speed, processing power and price determines the

category it best fits.

ConvergenceThe overlapping of computers and devices with technology,

examplenew cell phone often include media player, camera, and Web

browsing capabilities.



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Categories of Computers, (Cont) Summary of categories of computer


Category Physical Size Number of

Simultaneous Users

General Price Range

Personal Computers Fits on Desk Usually one (Can be

more if networked)

Several $100s - $1000s

Mobile computers

and mobile devices

Fits in your lap or in

your hand

Usually one Less than $100s to

$1000s

Games Consoles Small box or

handheld devices

One to several Several $100s or less

Servers Small cabinet Two to thousands Several $100s to million

dollars

Mainframes Partial room to a full

room of equipment

Hundreds to

thousands

$300,000 to several

millions

Supercomputers Full room ofequipment

Hundreds tothousands

$500,000 to severalbillions

Embedded

Computer

Miniature Usually one Embedded in the price of

the product


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Categories of Computers, (Cont)Personal Computers (Desktop):

The two most popular personal computers are PC (Windows, Linux) and

Apple Macintosh (Mac OS). Desktop computers are so described because their components are

designed to fix on or under ones desk.



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Categories of Computers, (Cont)Mobile computers and mobile devices:

These technologies are small enough to carry around in ones pocket; such

devices usually have internet enabled (smart phones). Handheld computers are those devices small enough to fit in one hand;

often used by mobile employeesmeter readers or delivery persons.

Personal Digital Assistants (PDA) are used as organizers with calendar,

calculator, address book, appointment booking and even notebook.

A smart phone is an Internet-enabled telephone that usually provides PDAcapabilities; while, a smart watch is an Internet-enabled watch that

automatically adjusts to time zone changes and stores personal information.

Notebook computers, also called laptops, are portable computers that tend

to be more expensive than desktops.

Tablet PC, resembles a letter-sized slate which is useful for note taking.



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Categories of Computers, (Cont)Game Console:

A game console is a mobile computing device designed for single player or

multiplayer video games. Standard game consoles are use a handheld controller(s) as an input

device(s); a television screen as an output device; and hard disks, optical

discs, and/or memory cards for storage.



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Categories of Computers, (Cont)Midrange servers:

Powerful, large computer that supports up to a few

thousand computers.

Mainframe:

Very powerful, expensive computer that supports

thousands of computers.

Supercomputer:

The fastest, most powerful, most expensive computer.

Used for applications requiring complex mathematicalcalculations.



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Categories of Computers, (Cont)Embedded computer:

Typically, these computers are special-purpose computers, with functions that are

part of a whole system.



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Categories of UsersHome:

Hardware Usage:

Desktop or notebook computer Smart phone or other mobile device

Game consoles

Software Usage:

Business (e.g., word processing)

Personal information manager

Personal finance, online banking

Web browser

E-mail, blogging, instant messaging, chat rooms, online and social

networking

Internet telephone calls Photo and video editing

Reference (e.g., encyclopedias, medical dictionaries, road atlas)

Entertainment (e.g., games, music composition, greeting cards)

Education (e.g., tutorials, children's math and reading software)



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Categories of UsersSmall Office/Home Office:

Hardware Usage:

Desktop or notebook computer Smart phone or other mobile device

Shared network printer

Software Usage:

Business (e.g., word processing, spreadsheet, database)


Company specific (e.g., accounting, legal reference)

Network management

Web browser

E-mail

Internet telephone calls



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Categories of UsersMobile:

Hardware Usage:

Notebook computer equipped with a wireless modem, or a Tablet PC Video projector

Smart phone or other mobile device

Handheld game consoles

Software Usage:

Business (e.g., word processing, note taking, presentation)


Web browser

E-mail



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Categories of UsersPower:

Hardware Usage:

Workstation or other powerful computer with multimedia capabilities Smart phone or other mobile device

Software Usage:

Desktop Publishing

Multimedia authoring

Computer-aided design

Photo, audio, and video editing


Web browser

E-mail



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Categories of UsersEnterprise:

Hardware Usage:

Server or mainframe Desktop or notebook computer

Industry-specific handheld computer

Smart phone or other mobile device

Software Usage:

Business (e.g., word processing, spreadsheet, database)


Accounting

Network management

Web browser

E-mail

Blogging



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Memory

Memory (RAM & ROM, Cache)

Primary - also called IAS (immediate access storage), main storage, main memory.

To hold data and instructions after input until needed.

Hold info awaiting output.

Fast data instantly accessible.

Close proximity to the processor.

Data must be transferred here before it can be processed.

Expensive - contained in a semi-conductor chip. Part of O/S remains resident in memory.

Instructions awaiting to be obeyed, Instructions currently being obeyed

Data awaiting processing Data currently being processed, Data awaiting output.

Made up of silicon and galium (semiconductors) on the motherboard.

The motherboard is the main circuit board, on it are mounted the microprocessor, memory chips,

slots for adding other circuit boards.

RAM

Random access memory - another name for main storage.

Arranged like series of boxes, numbered from 0, so know location.

Once data placed in each box it remains until replaced by more.

Each location has a 0 or 1.

Volatile - info lost if power switched off.


M


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Memory

There are different types of RAM

Examples

DRAM (dynamic RAMneeds to be reenergized constantly).

SRAM (static RAM), SIMM, DIMM (dual inline memory modulepins are on opposite side of

circuit board).

SDRAMsynchronous because synchronized to system clock).

ROM

Read only memory. Permanently written during manufacture.

Non-volatile - info kept even if power switched off.

Firmware - software instructions held in ROM (contents hard wired into device).

Controls the function of the machine. ROM extends computer instruction set, O/S, control S/W for peripherals.

CMOS

Complementary Metal-Oxide semiconductor.

A chip that holds computer settings/configuration.

Example - Date, start up info, keyboard. A battery is used to keep the information.

PROM Programmable read only memory.

Able to have data and programs written in them after manufacture, but once written become

permanently fixed.

Used to provide permanent instruction capability to microprocessor on functions to perform each

time it is used.

Does not lose data when power turned off.



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Memory

EPROM

Erasable PROM - PROMS which may be erased by a special process (e.g. thru exposure to ultra

violet light) and written again as a new PROM.

EAPROM Electrically alterable ROM - a variant of EPROM.

RAMdisk

RAM used as if it were hard disk. (e.g. palm top, data bank).

Also called silicon disks.

Advantage is fast performance.

Cache A special high speed memory that operates at the speed of the processor.

It holds data or instructions that were recently used in anticipation that it will be required in the

near future.



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Social, Legal, Ethical, and Economic ImplicationsSocial

Social networksRevolutionizes communication in 2009.

Social network website encourages members in its online community to share their interests,

ideas, stories, photos, music, and videos with other registered users.

ExampleFacebook and mySpace

Netiquette

Short for internet etiquette.

The code of acceptable behaviours users should follow while on the internet.

Include rules for all aspect of the internet including the WWW, e-mail, instant messaging, chat

rooms, FTP, newsgroups and message boards.

Rules includekeep messages short, be polite, avoid sending flames (abusive or insultingmessages sent on the internet) or spam, use emoticons (symbols used on the internet to express

emotions) and acronyms, clearly identify a spoiler (message that reveals a solution to a game or

ending to a movie or program), read the FAQ, do not assume materials are up to date, and never

read someones private e- mail

Legal

Computer crime - Any illegal act involving the computer

Examplecopying software illegally

Identity theft - Scam artists using techniques such as phishing to try to steal personal ID.

PrivacyI Invasion of privacy (personal records) using the computer.

Plagiarism copying information from the internet

Copyright infringementinfringement on rights to given to authors and artists to duplicate, copy,

duplicate and sell their produces.



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Social, Legal, Ethical, and Economic ImplicationsEthical

Academic integrity - honesty and responsibility

Software piracy computer risk

Pornography Ten Commandment for Computer Ethics - The Ten Commandments of Computer Ethics were

created in 1992 by the Computer Ethics Institute

1. Thou shall not use a computer to harm other people.

2. Thou shall not interfere with other people's computer work.

3. Thou shall not snoop around in other people's computer files.

4. Thou shall not use a computer to steal.

5. Thou shall not use a computer to bear false witness.

6. Thou shall not copy or use proprietary software for which you have not paid.

7. Thou shall not use other people's computer resources without authorization or proper

compensation.

8. Thou shall not appropriate other people's intellectual output.

9. Thou shall think about the social consequences of the program you are writing or the system

you are designing.

10. Thou shall always use a computer in ways that ensure consideration and respect for your

fellow humans.

Economic

Cost of access -

Virtual companies and taxation They open up business opportunities on the Internet for people

who might never have been able to have their own business

http://en.wikipedia.org/wiki/Computer_Ethics_Institutehttp://en.wikipedia.org/wiki/Computer_Ethics_Institute


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Social, Legal, Ethical, and Economic Implications Job creationIT predicted to be the fastest growing industry for the next 10 years.

Job loss -


f


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ReferencesGary, B. Shelly and Misty E. Vermaat, (2010). Discovering Computer 2010:

Living in a Digital World, Complete. Boston: Course Technology

unit 1_introduction computers and it_fund of it

Documents