Computer Viruses

Virus:
A computer virus is a computer program that can copy itself and infect a computer. The term "virus" is also commonly but erroneously used to refer to other types of malware.
Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.

Malware:
Short for malicious software, is software designed to infiltrate a computer system without the owner's informed consent.
Malware includes computer viruses, worms, trojan horses, spyware, crimeware, most rootkits.

Worm:
is a self-replicating malware computer program. It uses a computer network to send copies of itself to other nodes (computers on the network) and it may do so without any user intervention. This is due to security shortcomings on the target computer. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.

Trojan Horse:
A Trojan horse, or Trojan, is malware that appears to perform a desirable function for the user prior to run or install but instead facilitates unauthorized access of the user's computer system. "It is a harmful piece of software that looks legitimate. Users are typically tricked into loading and executing it on their systems", as Cisco describes.
A Trojan horse may modify the user's computer to display advertisements in undesirable places, such as the desktop or in uncontrollable pop-ups, or it may be less notorious, such as installing a toolbar on to the user's Web browser without prior mentioning.
Once a Trojan horse has been installed on a target computer system, a hacker may have access to the computer remotely and perform various operations, limited by user privileges on the target computer system and the design of the Trojan horse

Spyware:
Spyware is a type of malware that is installed on computers and collects little bits of information at a time about users without their knowledge. The presence of spyware is typically hidden from the user, and can be difficult to detect. Typically, spyware is secretly installed on the user's personal computer. Sometimes, however, spywares such as keyloggers are installed by the owner of a shared, corporate, or public computer on purpose in order to secretly monitor other users.

Crimeware:
Crimeware is designed to perpetrate identity theft in order to access a computer user's online accounts at financial services companies and online retailers for the purpose of taking funds from those accounts or completing unauthorized transactions that enrich the thief controlling the crimeware.

Rootkit:
Rootkits can target the BIOS, hypervisor, boot loader, kernel or less commonly, libraries or applications.
The most common forms of rootkit either damage the systems they occupy or redirect the systems' resources for purposes ranging from pranks to gratifying their authors' egos to crime. 

Virus vs. Worm:
A virus stays on your computer and your computer only. 
Worms crawl through networks.
Unlike a worm, a virus cannot infect other computers without assistance. It is spread via trading programs with others (file sharing programs, email). 

Spyware  vs. Adware:
Symptoms: Sluggish Pc, Increased pop-ups, homepage changes, strange search results.
Both are data miners, meaning they are looking for information. Both cause the above symptoms.
Can lead to identity theft. 
9 out of 10 pc’s are infected.
Good place to look for info? http://www.webroot.com/spywareinformation

Spyware Removal:
You can try to do it manually- but is often very difficult.  
Often it can disrupt major computer processes.
You can check out the following free programs:
AdAware
SpySweeper (both versions, free&pay)
NOTE: Please be careful when downloading these tools, some programs claim to remove spyware, but instead, come with their own spyware embedded.

Top Spyware Threats:
PurityScan
N-Case
Gator
CoolWebSearch
Tansponder
ISTbar/AUpdate
KeenValue
Internet Optimizer (bargain buddy)
Perfect Keylogger
TIBS Dialer

For more information on these, visit:
http://www.webroot.com/spywareinformation/spywaretopthreats/

Basic Computer Maintenance

LCD Monitor:
- Do not touch or attach items to the screen.
- Turn off to clean.
- Spray mild window cleaner on a soft cloth.
- Do not spray directly on screen.
- Do not use paper towels.

Wires:
- Avoid pulling or putting stress on your wires.
- Avoid putting objects on top of wires.
- Always disconnect cords by grasping the plug, not the cord.

CPU:
-Turn power off before cleaning.
- Any type of household cleaner for outside.
- Once a month take off cover and gently blow off dust.
- Always disconnect power cord by grasping plug- not cord.

Surge Protectors:
- Use a surge protector to protect electronic devices from power surges.
- Will not offer 100% protection.
- To be safe, never use computer during a storm.

CD-ROM Drives:
- Always use the button to open and close the drive.
- Do not use compressed air to clean the floppy diskette, CD, DVD or Zip drives.

CDs and DVDs:
- Use a soft cotton cloth
- Wipe against the tracks starting from the middle and wiping outwards
- Never wipe with the tracks
- Water w/ soap or rubbing alcohol

Keyboard:
- Do not eat or drink while typing on your computer.
- Turn off before cleaning.
- Spray Windex onto cloth, not on keyboard
- Use Compressed air

Mouse:
- Clean the top of your mouse like your keyboard
- Scrape guck off bottom with your fingernail

Installing Software:
- Do not use “bootleg” software
- Be sure to reboot after each program is installed
- Test your computer for problems before installing another program

Protect Against Viruses:
- Don’t open email attachments from people you don’t know.
- If your computer suddenly starts acting strange, you should run a virus scan.
- Be careful about disks and CDs from other computers- not everyone has virus protection.
- Use a firewall. A firewall is a piece of software or hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the internet.
- Be careful about what you download from the Internet!
- Be sure that everyone who uses your computer follows these rules!

General Troubleshooting:
- If your computer does not start the first thing to check is the power source… is it plugged in?
- If your computer locks up (freezes) the first thing you should do is restart the computer.
- If your document fails to print you should check the
    a. paper supply, 
    b. power source, 
    c. paper feeder. 
- If you install a new software program on your computer and it does not work the most likely reason is that you do not have enough memory.LCD Monitor:
- Do not touch or attach items to the screen.
- Turn off to clean.
- Spray mild window cleaner on a soft cloth.
- Do not spray directly on screen.
- Do not use paper towels.

Wires:
- Avoid pulling or putting stress on your wires.
- Avoid putting objects on top of wires.
- Always disconnect cords by grasping the plug, not the cord.

CPU:
-Turn power off before cleaning.
- Any type of household cleaner for outside.
- Once a month take off cover and gently blow off dust.
- Always disconnect power cord by grasping plug- not cord.

Surge Protectors:
- Use a surge protector to protect electronic devices from power surges.
- Will not offer 100% protection.
- To be safe, never use computer during a storm.

CD-ROM Drives:
- Always use the button to open and close the drive.
- Do not use compressed air to clean the floppy diskette, CD, DVD or Zip drives.

CDs and DVDs:
- Use a soft cotton cloth
- Wipe against the tracks starting from the middle and wiping outwards
- Never wipe with the tracks
- Water w/ soap or rubbing alcohol

Keyboard:
- Do not eat or drink while typing on your computer.
- Turn off before cleaning.
- Spray Windex onto cloth, not on keyboard
- Use Compressed air

Mouse:
- Clean the top of your mouse like your keyboard
- Scrape guck off bottom with your fingernail

Installing Software:
- Do not use “bootleg” software
- Be sure to reboot after each program is installed
- Test your computer for problems before installing another program

Protect Against Viruses:
- Don’t open email attachments from people you don’t know.
- If your computer suddenly starts acting strange, you should run a virus scan.
- Be careful about disks and CDs from other computers- not everyone has virus protection.
- Use a firewall. A firewall is a piece of software or hardware that helps screen out hackers, viruses, and worms that try to reach your computer over the internet.
- Be careful about what you download from the Internet!
- Be sure that everyone who uses your computer follows these rules!

General Troubleshooting:
- If your computer does not start the first thing to check is the power source… is it plugged in?
- If your computer locks up (freezes) the first thing you should do is restart the computer.
- If your document fails to print you should check the
    a. paper supply, 
    b. power source, 
    c. paper feeder. 
- If you install a new software program on your computer and it does not work the most likely reason is that you do not have enough memory.

Computer Hardware - General Overview

Programming  -is about Software…why do we have to learn about Hardware and other stuff?

Computer Systems

Hardware
Software


Hardware=The physical components (electrical circuits) that make up the computer

Software=The computer programs (sequences of instructions) that tell the computer what
to do in response to a command or some event.

How do we communicate with computers?
Through the use of binary Language.

Components of a Computer
- Input Devices
- Precessing Devices
- Storage Devices (Primary and Secondary)
- Output Devices.

Computer Processing System:
1. Data is INPUT
2. Data is Processed
3. There is an OUTPUT

IPO - Input, Process, Output.
or commonly known as GIGO - Garbage In, Garbage Out.

Types of Computer
- Microcomputer
- Minicomputers
- Mainframe Computers
- Supercomputers

Minicomputers
-Multi-user systems
-100’s of workstations or terminals attached to central minicomputer
-E.g. EPOS (Electronic Point of Sale) Systems

Mainframe computers

Large Organisations –banks, building societies, airlines, governments

May have 1000’s of terminals –geographically remote locations
Could occupy a whole site
100’s of disk drives & hardware units
Location often kept secret! (terrorist attacks)

Supercomputers

Largest Category of computer
Cost MillionsMostly used by scientific and industrial research departments
NASA –government agenciesWeather Centres
Stock Exchanges
Large Commercial Organisations

The processor
 
 What is the equivalent (in humans) to the processor?
 The Human Brain.

How does the Brain process?
-receives an instruction (stimulus)
-decodes & produces an appropriate instruction
-executes the instruction!
-slap on the cheek –anger/revenge etc logged
-anger decoded –instruction to slap back
-slap back!
(OR TURN THE OTHER CHEEK?)

Processor:
-Brain of the computer
-Processes instructions

THREE STEPS
1) Fetches Instructions
2) Decodes Instruction
3) Executes Instruction

What is a Processor?
-Most computers use integrated chips….or integrated circuits for their processors or main
memory
-A chip is about 1cm square…and can hold MILLIONS of electronic components such as
transistors and resistors
-CPU of a microcomputer is a microprocessor
-Processor and MAIN MEMORY of a PC are held on a single board called a motherboard.
-Either chips or integrated circuits
-Integrated circuits are also found in almost every modern electrical device such as cars, television sets, CD players, cellular phones, etc.


 CHIP
A computer chip is an electronic circuit (consisting mainly ofsemiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material.


An electric circuit is made from different electrical components such astransistors, resistors, capacitors and diodes, that are connected to each other in different ways. These components have differentbehaviors.


The transistor acts like a switch
Resistor –resists electricity –so you can control current
Capacitor –controls electricity
Diode –also allows control of current and flow

Why Integrated Circuits (transistors)?
-Before –there were VACUUM TUBE
-They were huge –costly –bulky –easily burned out
-The first Computer –ENIAC –huge 30 ton monster! *use of 18000 or so vacuum tubes*

MAIN MEMORY
-The program currently being executed and the data used by the program is held in MAIN
MEMORY
-MM is divided into millions of individually addressable storage units called BYTES
-One byte can hold one character
-Or one byte can hold a code representing something –i.e a part of a picture, or a sound, or
 a program instruction.
-The total number of bytes in MM = The computers MEMORY SIZE.

Computer Memory Sizes
-1 KB (KB)    =1024 Bytes
-1 MB           =1024KB
-1 GB  =1024MB
-1Tb  =1024GB (about 1 trillion bytes)
 
 Main Memory
-Processing power and Main Memory in a computer has increased exponentially in the past year! It has grown at a rate that no one could have predicted.
-1980 –Microcomputers with 32K of memory were bought for thousands of homes and schools!

RAM and ROM
-There are two kinds of Memory
-RAM –Random Access Memory (MM)
(this is used for storing programs that are currently running and data that is being
processed)

ROM –Read Only Memory
(its contents are PERMANENTLY etched into the memory chip at the manufacturing stage. It
is used –for example –to load the bootstrap loader (the program that loads as soon as you
start the machine)

RAM
-Random Access memory
-Main Memory
-Stores info about applications that are open and data
-VOLATILE –
-When you switch off the machine, it disappears!!!

ROM
-Read only memory
-Non-Volatile (does not change)
-Programs that are necessary for the computer to run
-Boot up program
-etc

 Cache Memory

-This is a very FAST type of memory that is used to improve the spped of a computer, DOUBLING it ….in some cases.
-Acts as an intermediate store between CPU and MM
-It works by storing most frequently or recently used instructions so that it is fast to retrive them again.
-Cache is usually between 1KB and 512KB

Disk Storage
-Auxiliary storage is also called
-SECONDARY MEMORY
-BACKING STORE

EXTERNAL MEMORY
-The most common secondary memory (auxiliary storage) is DISK!

Hard disk  & Floppy Disk
All standalone PC’s come equipped with an in-built hard disk –the capacity of which is also measured in BYTES.

A typical hard disk nowadays is several gigabytes - - is used for storing software including the OPERATING SYSTEM..and other systems software.
Other types of Storage
-Flash Memory Cards
-Sticks
-Floppy discs
-Disks
 
INPUT AND OUTPUT devices
Input devices
-are the means whereby computers can accept data or instructions
-Keyboards, magnetic strip cards, smart cards, magnetic ink character recognition devices,

Output
–printer, VDU monitors, speakers, etc

There are two types of software:
-Systems software: the operating system.
-Applications software: the programs we use.
*Systems software is the control software that operates the hardware and allows the applications to run.

OPERATING SYSTEMS
-Operating Systems run in the background without the users being aware of it.
-It controls the inputs, outputs, interrupts, and storage of files as requested by the applications software.
APPLICATIONS SOFTWARE
ÒUsed for a specific purpose or application.
-Word processing;
-Numerical analysis and storage;
-Recording of data;
-Designing and graphics;
-Image processing;
-Presentations;
-Desk top publishing;
-Web design.

Generations of Computers

The Five Generations of Computers

First generation computers
(1940-1956) - Vacuum Tubes

- The first computers used vacuum tubes for circuitry and magnetic drums for memory.

—- They were often enormous and taking up entire room.

—- First generation computers relied on machine language.

—- They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions.

—- The UNIVAC and ENIAC computers are examples of first-generation computing devices.

 Second generation computers
(1956-1963) - Transistors

- Transistors replaced vacuum tubes and ushered in the second generation of computers.

- Second-generation computers moved from cryptic binary machine language to symbolic.

- High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN.

- These were also the first computers that stored their instructions in their memory.

 Third generation computers
(1964-1971) - Integrated Circuits

- The development of the integrated circuit was the hallmark of the third generation of computers.

—- Transistors were miniaturized and placed on siliconchips, called semiconductors.

—- Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system.

—- Allowed the device to run many different applications at one time.

 Fourth generation computers
(1971-present) - Microprocessors

 

- The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip.

—- The Intel 4004 chip, developed in 1971, located all the components of the computer.

—- From the central processing unit and memory to input/output controls—on a single chip.

—- Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.

Fifth generation computers
(present and beyond) - Artificial Intelligence

- Fifth generation computing devices, based on artificial intelligence.

—- Are still in development, though there are some applications, such as voice recognition.

—- The use of parallel processing and superconductors is helping to make artificial intelligence a reality.

—- The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.

History of Computer

 Abacus 
- 3000 BCE, early form of beads on wires, used in China
- From semitic abaq, meaning dust.


Charles Babbage (1791-1871) 

Born: December 26, 1791 

son of Benjamin Babbage a London banker (part of the emerging middle class: property, education, wealth, and status) 

Trinity College, Cambridge  [MA, 1817]with John Herschel and George Peacock, produced a translation of LaCroix’s calculus text.  

December 1830, a dispute with his chief engineer, Joseph Clement, over control of the project, ends work on the difference engine

Clement is allowed to keep all tools and drawings by English law

Importance of the Difference Engine

1. First attempt to devise a computing machine that was automatic in action and well adapted, by its printing mechanism, to a mathematical task of considerable importance.

2. An example of government subsidization of innovation and technology development

3. Spin offs to the machine-tool “industry”

Ada Augusta Byron, 1815-1852

born on 10 December 1815.

named after Byron's half sister, Augusta, who had been his mistress.

After Byron had left for the Continent with a parting shot -- 'When shall we threemeet again?' -- Ada was brought up by her mother.

Translated Menebrea’s paper into English

Taylor’s: “The editorial notes are by the translator, the Countess of Lovelace.”

Footnotes enhance the text and provide examples of how the Analytical Engine could be used, i.e., how it would be programmed to solve problems!

Myth: “world’s first programmer”

Herman Hollerith (1860-1929)

Born: February 29, 1860

Columbia School of Mines (New York)

1879 hired at Census Office

1882 MIT faculty (T is for technology!)

1883 St. Louis (inventor)

1884 Patent Office (Wash, DC)

1885 “Expert and Solicitor of Patents”


Electronic Numerical Integrator and Computer

•1st large scale electronic digital computer

•designed and constructed at the Moore School of Electrical Engineering of the University of Pennsylvania

–since 1920s, faculty had worked with Aberdeen Proving Ground’s Ballistics Research Laboratory (BRL)

•1943 Mauchly and Eckert prepare a proposal for the US Army to build an Electronic Numerical Integrator

–calculate a trajectory in 1 second

•May 31, 1943 Construction of ENIAC starts

•1944 early thoughts on stored program computers by members of the ENIAC team

•July 1944  two accumulators working

Early Thoughts about Stored Program Computing

•January 1944  Moore School team thinks of better ways to do things; leverages delay line memories from War research

•September 1944  John von Neumann visits

–Goldstine’s meeting at Aberdeen Train Station

•October 1944  Army extends the ENIAC contract  to include research on the EDVAC  and the stored-program concept

•Spring 1945  ENIAC working well

•June 1945  First Draft of a Report on the EDVAC: Electronic Discrete Variable Automatic Computer

First Draft Report (June 1945)

•John von Neumann prepares (?) a report on the EDVAC which identifies how the machine could be programmed (unfinished very rough draft)

–academic: publish for the good of science

–engineers: patents, patents, patents

•von Neumann never repudiates the myth that he wrote it; most members of the ENIAC team ontribute ideas

Manchester Mark I (1948)

•Freddy Williams and Tom Kilburn

•Developed an electrostatic memory

•Prototype operational June 21, 1948 and machine to execute a stored program

•Memory: 32 words of 32 bits each

•Storage: single Williams tube (CRT)

•Fully operational: October 1949

•Ferranti Mark I delivered in February 1951

EDSAC

•Maurice Wilkes, University Mathematical Laboratory, Cambridge University

•Moore School Lectures

•Electronic Delay Storage Automatic Calculator, EDSAC operational May, 1949

•J. Lyons Company and the LEO, Lyons Electronic Office, operational fall 1951

National Physical Laboratory

•Alan Turing

•Automatic Computing Engine (ACE)

•Basic design by spring, 1946

•Harry Huskey joins project

•Pilot ACE working, May 10, 1950

•English Electric: DEUCE, 1954

•Full version of ACE at NPL, 1959

Remington Rand UNIVAC

•43 UNIVACs were delivered to government and industry

•Memory: mercury delay lines: 1000 words of 12 alphanumeric characters

•Secondary storage: metal oxide tape

•Access time: 222 microseconds (average)

•Instruction set: 45 operation codes

•Accumulators: 4

•Clock: 2.25 Mhz

Additional Information:

Computer History

The history of the computer owes its existence to the fact that people, who are lazy by nature, have always sought to improve their ability to calculate, in order to reduce errors and save time.

Origins: The abacus

The "abacus" was invented in the year 700; it was in use for a long time, and still is in some countries.

Then came the logarithm

The invention of the logarithm is generally credited to the Scotsman John Napier (1550-1617). In 1614, he showed that multiplication and division could be performed using a series of additions. This discovery led, in 1620, to the invention of the slide rule.

However, the true father of logarithm theory is Mohamed Ybn Moussa Al-Khawarezmi, an Arab scholar from the Persian town of Khawarezm. This scholar also developed algebra, a term which comes from the Arabic "Al-Jabr", meaning compensation, with the implication being "looking for the unknown variable X in order to compensate by balancing the results of the calculations."

The first calculating machines

In 1623, William Schickard invented the first mechanical calculating machine.

In 1642, Blaise Pascal created the arithmetic machine (called the Pascaline), a machine that could add and subtract, intended to help his father, a tax collector.

In 1673, Gottfried Wilhelm Von Leibniz added multiplication and division to the Pascaline.

In 1834, Charles Babbage invented the difference engine, which could evaluate functions.

However, once he learned that a weaving machine (called a Jacquard loom) was programmed with perforated cards, he started building a calculating machine that could take advantage of this revolutionary idea.

In 1820, the first four-function mechanical calculators debuted. They could:

• add

• subtract

• multiply

• divide

By 1885, they were being built with keyboards for entering data. Electrical motors quickly supplanted cranks.

Programmable computers

In 1938, Konrad Zuse invented a computer based around electromechanical relays: The Z3. This computer was the first to use binary instead of decimals

In 1937, Howard Aiken developed a programmable computer 17 metres long and 2.5 metres high, which could calculate 5 times faster than a human.

It was IBM's Mark I.

It was built using 3300 gears and 1400 switches linked with 800 km of electrical wiring.

In 1947, the Mark II appeared, with its predecessor's gears being replaced by electronic components.