Computer Literacy new version

1. How Computers Work

What is a computer?
- A device that accepts input - process data - stores data - produce output all according to a series of stored instructions.

Data Processing Cycle
- Data Input / Processing / Information Output / Storage

Data vs. Information
- Data - in a format computer can understand and use
- Information - in a format people can understand and use

Digital vs. Analog
- Digital device works with discrete, distinct and separate data
- Analog device works with continuous data

Data representation
- is the process of transforming diverse data into a form that computers can use for processing.
- computers typically represent data digitally.

bit - binary digit.
- computers use sequences of bits to digitally represent numbers, letters, punctuation marks, music, pictures and videos.

Numeric data - numbers that might be used in arithmetic operations.
- computers represent numeric data using the binary number system

binary number system - has only two digits 0 and 1, no numerial like "2" exists. "2" is represented in binary as "10"

Character data - letters, symbols and numerals that are not used in arithmetic operations.
- computers employ several types of codes to represent character data - ASCII / EBCDIC / Unicode

digitize - means to convert raw, analog data into digital format represented by 0s and 1s.

file header
- when a computer works with a series of 1s and 0s, how does it know which code to use?
- to avoid confusion, most computer files contain a file header with information on the code used to represent the file data.
- a file header is stored along with the file and can be read by the computer, but never appears on the screen.
- by reading the header information, a computer can tell how a file's contents were coded.

Quantifying Bits and Bytes
- Bit - One binary digit
- Byte - 8 bits
- Kilobit - 1,024 or 210 bits
- Kilobyte - 1,024 or 210 bytes
- Megabit - 1,048,576 or 220 bits
- Megabyte - 1,048,576 or 220 bytes
- Gigabit - 230 bits
- Gigabyte - 230 bytes
- Terabyte - 240 bytes
- Petabyte - 250 bytes
- Exabyte - 260 bytes

Hardware vs. Software
- Hardware is tangible / Software is intangible
- Hardware makes up by electric, electronic and mechanical equipment
- Software makes up by 1's and 0's that stored on disk or memory which allow computer to perform tasks

Integrated Circuit (IC)
- is a super-thin slice of semiconducting material packed with microscopic circuit elements, such as wires, transistors, logic gates, and resistors.

Semiconductors
- such as silicon and germanium, are substances with properties between those of a conductor (like copper) and an insulator (like wood).


Microprocessor - CPU
- Control Unit - fetches instructions and data
- Arithmetic / Logic Unit (ALU) - perform the instruction

Instruction Sets


Storage Technology
- Magnetic Storage - stores data by magnetizing microscopic particles on the disk or tape surface
- Optical Stroage - store data as microscopic light (lands) and dark (pits) spots on the disk surface.
- Solid State Storage - store data in a non-volatile, erasable, low-power chip.


2. The Operating System

Software
- A set of files that contain the instruction that a programmer has written to tell the computer how to process certain data

Software Types
- Application Software - help people carry out tasks using a computer
- System Software - operating system / device drivers / utilities - help the computer carry out its basic operating functions

What does the OS do?
- Provide a common interface for hardware and software
- Manages Processor resources - multi tasking
- Manages memory allocation and protection
- Manages files and storage resources
- Manages system security - file access and desktop access
- Maintains system integrity - error handling
- Provides a user interface (GUI or CLI)

user interface - the combination of hardware and software that helps people and computers communicate with each other.

bootstrap program - is stored in ROM and supplies the instruction needed to load the OS's core into memory when the system boot.

kernel - is the core part of the OS stays in memory all the time your computer is on, provides the most essential operating system service, such as memory management and file access.

utilities - provided by OS that you can use to interact directly with the OS to control and customize your computer equipment and work environment. utilities are loaded into memory as they are neded.

Multi tasking
- processor in the computer runs one process for a short peroid of time, then switches to the next process and so on.
- the processor executes billions of instructions per second, appears that many processes are running at the same time.

Processes
- is part of a program
- each process runs in an operating system is assigned specific information such as process ID, priority. state information and its location in memory

Cooperative vs. Preemptive Multitasking
- cooperative - one program can "hog" the processor time - cause system not stable
- preemptive - OS controls time slicing of the processor time - much more stable

Thread
- is a separate part of a process
- some OS support multi-threading
- each independent thread will handle a separate part of a process

Multi-Processing
- OS support computer with multiple CPUs
- individual processes and threads are run simultaneously on each processor
- OS support multi-processing, performance improved a lot.

Single-User OS vs. Multi-User OS
- Allow only one user to access the computer system at a time
- allows more than one user to access the computer system at one time, may through an network

Why Multi-User OS
- Share applications
- Access applications from other computers
- Quickly deploy and update applications

Software Copyright and Licensing
- Copyright - grants the author of an original "work" the exclusive right to copy, distribute and sell that "work".
- Software License - define how you may use the software
- single license - allows you to install the software on one computer or more computers but only use one at a time.
- Concurrent use license - allow the software to be installed on many computers but only a few may be in use at any one time
- other type of software licenses - Shareware / Freeware / Open Source

Document Production Software
- assists you with composing, editing, designing, printing, and electronically publishing documents
- word processing software - replaced type writers for producing documents such as reports, letters, memos, papers, and manuscripts.
- desktop publishing software - help you use graphic design techniques to enhance the format and appearance of a document, produce professional-quality output for newspapers, newsletters, brochures, magazines, and books.
- web authoring software - design and develop customized web pages that you can publish electronically on the internet .

Spreadsheet Software
- tools to create electronic spreadsheets, which uses rows and columns of numbers to create a model or representaion of a real situation.

Number crunching software
- works more like "paint by numbers" it provides a structured environment dedicated to a particular number crunching task, such as statistical analysis, mathematical modeling, or money management.

Database Software
- helps you enter, find, organize, update and report information stored in a database.

Graphics Software
- designed to help you create, manipulate, and print graphics.

Music Software
- tools to make , recording, modify digital voice and music.

Video Editing and DVD authoring Software
- a set of tools for transferring video footage from a camcorder to a computer, clipping out unwanted footage, assembling video segments in any sequence, adding special visual effects, and adding a sound track.
- tools for creating DVDs with Hollywood-style menus, just like commercial movies.

Educational and Reference Software
- helps you learn and practice new skills.
- provides a collection of information and a way to access that information.

Entertainment Software
- computer games are the most popular type of entertainment software.

Business Software
- is a broad umbrella for vertical and horizontal market software, which are designed to help businesses and organizations accomplish routine or specialized tasks.
- Vertical market software - is designed to automate specialized tasks in a specific market or business. Examples include patient management and biling software,etc.
- Horizontal market software - is generic software that just about any kind of business can use. payroll software is a good example of horizontal market software.
- Groupware - is a type of horizontal market software, designed to help several people collaborate on a single project using LAN or Internet connections.


3. Microsoft Windows XP

XP vs. Windows 9x - improved stability and reliability / better security

XP vs. Windows NT/2000
- new user interface
- simplified networking - entirely wizard driven
- improved hardware and software compatibility
- fast user switching
- remote assistance / desktop
- system restore
- enhanced support for digital media
- driver verification

XP SP2
- security center dashboard
- enhanced firewall
- improved internet explorer security
- improved wireless connectivity

Home vs. Professional
- ability to connect to a windows network
- enhanced file security (more granular / encryption)
- built-in webserver
- remote desktop support

XP Hardware requirement
- CPU: Min. 233MHz, Rec. 300+ MHz
- RAM: Min. 64MB, Rec. 128MB
- Disk Space: 1.5GB
- Video: SVGA or Higher
- CD-ROM or DVD drive
- NIC (optional)
- Internet access (optional)

Start menu default folder - Accessories / Games / Startup


4. Files and File Organization

Files
- The fundamental building block of computer systems
- A file is a collection of electronic data on a computer
- A file is assigned a name and an extension
- The extension represents the type of file

File Types
- application & system files
- files that are part of the programs and the operating system on a computer
- you should never need to alter or move these files

- Data files
- files that someone creates using software
- these are the types of files you may need to organize and backup

File Name - Maximum 256 characters

File Extensions - usually 3 characters.
- reserved characters: \/:*?<>|

File organization - Why? / How?
- Locate your files quickly
- assign access permission easily
- backup file easily

- name your file logically and descriptively
- group files logically and by required permission

Windows Explorer - a utility provided to help you manage your files

Shortcut - is a pointer to an object on the local computer or network.


5. Control Panel & Accessories


6. Compression and Encryption
reduces file size
- transfer file over Internet more effeciently
- Reduce file storage needs on disk, etd
- generally reversible

Compression ratio
- measurement of the amount of shrinkage
- e.g. 20:1 - compressed file 20 times smaller

File compression types
- Lossless compression
- file can be restored without lost data.
- .zip, .sit, .gz, .TIFF, .PCX, .GIF
- Lossy compression
- unnecessary information discarded
- "lost" cannot be recovered
- result in degradation of file quality
- .jpg, .mp3, .avi, .mpg

Lossless Compression algorithm

Dictionary-based compression
- identify common character patterns / sequences
- replace with single codeword, or symbol
- symbol points to dictionary of original characters, words.

Statistical compression
- e.g. well-known Huffman algorithm
- characters that appear frequently are recoded as short bit patterns
- that appear infrequently are assigned longer bit pattern.

Lossy Compression algorithm

Spatial compression
- e.g. Run-length encoding (RLE)- an example of a lossless spatial compression
- replace patterns of pixels with code indicating number of pixels and their colours.
- JPEG is lossy version of RLE encoding applied to images.
- jpeg tweaks colours in adjoing pixels to same color where possible, RLE then can be appliced. but data will be lost.

Temporal compression
- reduce data between vido frames, audio samples
- key frames contain all data generated at major intervals
- only store change in data of new frames from key frame
- if even slight changes between frames eliminated - lossy
- MPEG use temporal and spatial algorithms (both lossy)


7. Multiple users and accounts

Types of User Accounts - Computer Administrator / Limited / Guest

Passwords - up to 14 characters

Best password practices
- rename the administrator and guest account to prevent hacking
- create a second administrator account. only use when installing hardware and software, and creating user accounts.
- creating limnited user account for all people using the computer including yourself

username - max 20 characters, not case sensitive


8. Computer Network

network computers advantageous
- sharing networked hardware and software can reduce cost
- sharing networked hardware can provide acces to a wide range of services and specialized peripheral devices
- sharing data on a network is easy
- networks enable people to work together regardless of time and place.

Bandwidth - is the transmission capacity of a communication channel, usually meausred in bits per second (bps)

Sharing vs. Security
- Sharing rights are the restrictions based on access through a network
- Security rights are restrictions hased on local or network access and apply in additon to the sharing rights.
- e.g. someone sitting at a computer may be able to access and change myFile.doc, however coming over the network they may only be able to read it.

Network Classifications
- Geographical Scope - PAN / LAN / MAN / WAN
- Organizational Structure - Peer to Peer / Client-Server
- Physical Topology - Star / Tree / Ring / Bus / Mesh
- Communication protocols - TCP/IP; NetBios/NetBEUI; AppleTalk; IPX/SPX
- Network links - cables
- Bandwidth

Hostname
- the unique "English" name by which a network resource (commonly a computer) is known on a network.

9. Backup, Virus, Firewall, Troubleshooting

Backup
- data backup - a copy of a file or the content of a disk drive
- provides the best all-round security for your data
- is usually on a different storage medium from the original files
- the exact steps you follow depend on your backup equipment, the software you use to make backups, and your personal backup plan

Backup Best Practices
- don't get caught without a backup of your important data!
- use offsite storage - protect your data from fire, thief and building damage by storing an additional copy elsewhere.
- set regimented schedule, maintain it

Virus and malware
- by definition a virus is a program that ** replicates ** itself and often cause damage to your computer
- there are many threats other than just viruses, these are often grouped as malware.
- can be destructive in numerous way
- deleting / corruping data and / or program files
- compromising privacy and secure transactions
- overloading network and servers
- modern viruses often need no interaction by you - they will install and run by themselves

Types of viruses and malware
- File Virus - attaches to a program file and replicates every time the program is launched
- Email Virus - replicates using your email address book
- Worm - replicates by exploiting known OS and server bugs
- Trojan Horse - (doesn't replicate) Virus disguised to look like a regular program / game
- spyware (doesn't replicate) - software that is installed deceptively and compromises your privacy
- phishing (doesn't replicate) - misleads you into thinking that you are at a website you trust

Virus Symptoms
- Strange messages on computer screen
- sluggish system performance
- inability to access your drivers
- missing or corrupt data
- slow network performance
- programs that won't launch
- denial of service
- browser reconfiguration
- access confidential information
- disable antivirus and firewall software

Virus and system protection
- regularly backup files so damage is minimized if virus attack occurs
- install commercial virus-detection SW
- update virus-detection SW regularly
- install malware / spyware detection software
- keep up to date with operating system and other software patches
- run a software firewall
- don't open attachment from unknown sources
- never give out password
- do as much as possible to confirm the site you are at before entering confidential information

Firewall
- Security system that acts as protective boundary between network and outside or between your computer and the network
- restricts what is transmitted, between your computer and the internet / lan

Hardware vs. Software Firewall
- hardware device sits at the connection point between your network and the internet - protects you from harmful content on the internet
- software is installed on your computer and protect you from harmful content that may be on your local network
- doesn't hurt to use both

Safe Mode
- allows you to boot the computer without loading any drivers
- will help you solve any driver related problems
- help clean up some viruses - run antivirus SW in safe mode
- to start in safe mode hit F8 while the cmputer is booting

Performance Issues
- insufficient RAM
- insufficient remaining hard drive space
- virus infection
- spyware infestation
- faulty program
- Too many things loaded at startup
- Fragmented hard drive
- etc.

Performance Issues possible solutions
- use the processes list to determine if any program have a memory leak ( use lots of RAM) Check for updates
- increase the RAM
- Check the free space on your hard drive
- use the disk cleanup wizard to help free up space on your hard drive
- De-frag hard drive
- scan for viruses and spyware
- etc.

Hardware Problem
- check for loose cables (power/data cables) inside and outside
- blow out accumulated dust (don't vacuum)
- ensure no diskette is in the floppy drive
- keep your drivers up to date
- view hardware status in Device Manager
- if a driver seems to be causing problems, use the driver rollback feature in winxp
- for previous version of windows, keep at least one earlier version of the driver install file

Hardware Failure
- may be caused by power surge / bumping computer / short circuit / faulty hardware
- determine which component is damaged
- may be obvious burns
- use a process of elimination
- hard drive failure means reformat or replace

Software problems
- try uninstalling and then re-installing - rebooting in between
- determine when SW last worked, and what has changed since then
- use Windows XP System Restore feature
- use the Program Compatibility Wizard


Network problems
- determine the area affected
- one computer indicates problem may be:
- software
- hardware driver
- network card
- network adapter (patch) cable to wall drop
- cable from wall to switch or hub

- many computers affected in an area - problem probably in a switch
- all computer affected - problem probably in a major router
- utilities - ping : determine if host is responding / tracert: trace route to host

Remote Assistant
- Tool found in all versions of windows xp that allows a remote user to assist you
- host send invitation by IM or email
- remote user connects and can view and text chat
- host can give full control to remote user