Computers & Programming Languages

Computers & Programming Languages
An Introduction to Programming Using Microsoft Visual Basic .NET

Mechanical Devices Pascaline (1642) Stepped Reckoner
Set of gears, similar to clock Only performed addition Stepped Reckoner Cylindrical wheel with movable carriage Add, subtract, multiply, divide, square roots Jammed/malfultioned

Mechanical Devices Difference Machine (1822) Analytical Machine (1833)
Charles Babbage Produce table of numbers used by ships’ navigators. Never built Analytical Machine (1833) Perform variety of calculations by following a set of instructions (or program) on punched cards Used as a model for modern computer

Mechanical Devices Babbage’s chief collaborator on the Analytical Machine was Ada Byron. Ada Byron Sponsor of Analytical Machine One of first people to realize its power and significance Often called the first programmer because she wrote a program based on the design of the Analytical Machine.

Electro-Mechanical Devices
Hollerith’s Tabulating Machine Herman Hollerith – used electricity For US Census Holes representing information to be tabulated were punched in cards Successful Mark I (1944) IBM & Harvard Mechanical telephone replay switches to store information and accepted data on punch cards. Highly sophisticated calculator - unreliable

First Generation Computers
Atanasoff-Berry Compter (ABC) Built b/w Used binary number system Vacuum tubes Stored info by electronically burning holes in sheets of paper. ENIAC Electronic Numerical Integration and Calculator 1943, 30 tons, 1500 sq ft., 17,000+ vacuum tubes Secret military project during WWII to calculate trajectory of artillery shells. Solve a problem in 20 min that would have take a team of mathematicians three days to solve.

What is a Computer? An electronic machine that accepts data, processes it according to instructions, and provides the results as new data.

The Stored Program Computer
Alan Turing & John von Neumann Mathematicians with the idea of stored programs Turing Developed idea of “universal machine” Perform many different tasks by changing a program (list of instructions) Von Neumann Presented idea of stored program concept The stored program computer would store computer instructions in a CPU.

Von Neumann, Mauchly and Eckert designed & built the EDVAC (Electronic Discrete Variable Automatic Computer) and the EDSAC (Electronic Delay Storage Automatic Computer) Designed to solve many problems by simply entering new instructions stored on paper tape. Machine language (1’s & 0’s)

Mauchly & Eckert built 3rd computer (UNIVAC - UNIVersal Automatic Computer) 1st computer language – C-10 (developed by Betty Holberton) Holberton also developed first keyboard and numeric keypad First UNIVAC sold to US Census Bureau in 1951

Second Generation Computers
1947, Bell Lab (Shockley, Bardeen, Brittain) Invented the transistor Replaced many vacuum tubes Less expensive, increased calculating speeds Model 650 (early 1960s) IBM introduced first medium-sized computer (Model 650) Still expensive

Second Generation Computers
Change in way data was stored Magnetic tape and high speed reel-to-reel tape machines replaced punched cards Magnetic tape gave computers ability to read (access) and write (store) data quickly and reliably

Programming Languages
Set of words, codes, and symbols that allow a programmer to give instructions to the computer. Low-level programming language Machine language First generation language Can be used to communicate directly with computer 0s and 1s Assembly language Second generation language Uses the same instructions and structure as machine language but the programmer is able to use meaningful names or abbreviations instead of numbers. 2005, ch1

High-Level Programming Languages
Third generation language More capabilities More widely used by businesses Led to need for high-level programming languages that had English-like instructions and were easier to use than machine language. Programmers convert the course code into machine language using a compiler or interpreter. Compiler A program that converts an entire program into machine code before the program is executed. Interpreter Translates and executes an instruction before moving on to the next instruction in the program. 2005, ch1

Fortran 1957 COBOL (COmmon Business Oriented Language) One of most widely used high-level languages Designed by Grace Hopper First developed by US Dept of Defense (1959) Ada Late 1970’s – named after first programmer High-level language that supports real-time applications

BASIC (1960’s) Kemeny & Kurtz developed at Dartmouth Univ. Widely used to teach programming to students in 70’s C Developed by Ritchie at Bell Labs in mid 1970’s Used to write a variety of applications

1980’s Object-Oriented Programming Evolved out of need to better develop complex programs in a systematic, organized approach. Allows programmers to create modules that can be used over and over again in a variety of programs Modules contain code called classes, which groups related data and actions C++, Java, Visual Basic .NET

Third Generation Computers
Integrated circuits (ICs) – replaced transistors Kilby and Noyce – working independently developed the IC (chip) ICs Silicon wafers with intricate circuits etched in their surfaces and then coated with a metallic oxide that fills in the etched circuit patterns IBM System 360 (1964) One of first comptuers to use IC

Mainframes A large computer that is usually used for multi-user applications IBM System 360 one of first mainframes Used terminals to communicate with mainframe

Fourth Generation Computer
Microprocessor (1970) Hoff at Intel Corp, invented microprocessor Entire CPU on a chip Makes possible to build the microcomputer (or PC) Altair – one of first PCs 1975 Wozniak and Jobs designed and build first Apple Computer in 1976 IBM introduced IBM-PC in 1981

The Personal Computer Hardware Physical components Input devices
Keyboard, mouse, cd/dvd, diskette drive Peripheral devices Scanner, printer Output device Monitor, printer

Desktop and Mobile Computing
Desktop computers are single-user systems designed with microprocessor technology where an entire CPU is contained on a single chip. Designed to fit on or under a desk. 2005 Book

Mobile computing devices Long-lasting batteries to allow them to be portable Notebook computers Portable, light-weight computers comparable to a desktop in capability Tablet PCs Similar to pad/pencil Write on screen with stylus (pen) Handwriting recognition software 2005 Book

Mobile computing devices Handheld computers PDAs Palm-sized Contains applications for storing contact information, schedules, lists and games. Use stylus for input Smart phones Cellular phones that are able to read and receive and access the Internet Some have cameras, video, mp3 players 2005 Book

Mobile computing devices Wearable computer Designed to be worn In clothing Wristband MP3 players, hands-free cell phones Monitor health problems 2005 Book

The Personal Computer Base Unit
Contains many storage devices such as a diskette drive, a cd/dvd drive, and a hard disk drive. Contains the motherboard which contains CPU (Central Processing Unit) Processes data and controls the flow of data between the computer’s other units. ALU (Arithmetic Logic Unit) Performs logic and arithmetic operations Makes comparisons So fast that the time need to carry out a single addition is measured in nanoseconds (billionths of a second)

The Personal Computer Contains the motherboard which contains
Expansion boards Circuit boards that connect to the motherboard to add functionality. (sound and video) **2005 Clock rate Determines the speed at which a CPU can execute instructions Megahertz (million of cycles per second) MHz Gigahertz (billion of cycles per second)GHz Memory Stores data electronically ROM – Read Only Memory Contains most basic operating instructions for computer Cannot be changed – permanent RAM – Random Access Memory Memory where data and instructions are stored temporarily Data stored in RAM can be written to any type of storage media (diskette, cd, jump drive)

The Personal Computer Contains the motherboard which contains
SRAM – Static Random Access Memory High-speed memory referred to as cache Used to store frequently used data for quick retrieval Bus Set of circuits that connect the CPU to other components Data Bus/Address Bus Transfers data between the CPU, memory and other hardware addresses that indicate where the data is located and where it should go Control Bus Carries control signals

Data Flow through the CPU
Input Memory Output CPU The “Brain” of the Computer

Networks A combination of software and hardware that work together to allow computers to exchange data and to share software and devices, such as printers A Network Allows user to reliably share and exchange data Can reduce costs by sharing devices (printers) Can be set up to allow users access to only specific files Simplifies the process of creating backup copies of files Allows users to communicate through

Networks Classified by size, architecture, and topology
LAN – Local Area Network Small area – building or campus WAN – Wide Area Network Large geographical distance Computers & other devices in a LAN contain a circuit board called a network interface card. Network operating system Software that allows users and devices to communicate between computers Networked environment A set of networked computers running an OS that can handle the communication between the computers

Networks Network Architecture
Includes the type of computers on the network and determines how network resources are handled. 2 Main Types Client/Server Groups of computers (clients) connected to a server Server manages network functions Peer-to-Peer No server Each computer equal in terms of responsibilities and resource sharing

Network Topology Physical Topology Logical Topology Bus Topology
The arrangement of nodes on a network. Logical Topology Logical arrange of nodes on a network Logical – how the data flows, not physical setup Node = a device such as a computer or printer Bus Topology Each node is attached to a single shared communication cable

Network Topology Star Topology
Each node is attached to a hub (a device that joins communication lines at a central location.

Network Topology Ring Topology
Connects each node to form a closed loop Data travels in one direction and is sent from node to node.

Number Systems Binary Number System (Base 2)
Electrical circuits on an IC have one of two states – one or off Uses 2 digits – 0 and 1 Code with eight binary digits grouped together to represent a single letter or number Bit BInary digiT Each 0 or 1 Byte Eight bits

Binary Number System (Base 2)
Converting Binary to Decimal 1 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 = 103 = 10310

Binary Number System (Base 2)
Converting Decimal to Binary 3310 = _____2 1 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 33 – 32 = 1 1-1=0 3310 =

Number Systems Hexadecimal – Base 16 Based on 16 digits 0 to 9, A to F
A = 10, B = 11…F = 15 163 162 161 160 4096 256 16 1

Hexadecimal (Base 16) Converting Hexadecimal to Decimal
3 163 162 161 160 4096 256 16 1 A = 10 (10 * 16) + (3 * 1) = 163

Hexadecimal (Base 16) Converting Decimal to Hexadecimal 36310 = ____16
163 162 161 160 4096 256 16 363 – 256 = 107 107 / 16 = so can have 6 107 – (16 * 6) = 11 11 left over is B

Number Systems Unicode
Every letter of an alphabet and symbol have been given a representation in a digital code called Unicode. A set of 16 1s and 0s to for a 16-bit binary code for each symbol.

Storing Data in Memory Storage is measured in bytes
MB = megabyte GB = gigabyte K = kilobyte Data stored in memory is referred to by an address A unique binary representation of a location in memory. Data is stored, accessed and retrieved by its address.

Storing Data in Memory Word Overflow Error
Bits grouped in units of 16 to 64 (2 to 8 bytes) Overflow Error Occurs when the number of bits that are needed to represent the integer is greater than the size of four bytes. Real Numbers – Floating Point Numbers Numbers that contain decimals

Storing Data in Memory Real Numbers
Binary representation is usually 4 to 8 bytes Bits that represent the mantissa (fractional part) are stored in one section of a work and the exponent is stored in another section of the word. Roundoff Error Not enough bits to hold the mantissa 1 mantissa exponent

What is a File? Related data stored on a persistent media
Can be an application (program) or the product of an application. Stored in binary code (1s and 0s) Computer translates it into symbols Text Files – human-readable files Binary Files – computer-readable files Distinguished by the extension Folders are used to organized commonly related files 2005 Book

Storage Devices Persistent media to maintain files
Drives, mass storage, auxiliary storage Internal or external 2005 Book

Intranet, Extranet, Internet
Network that is used by a single organization Only accessible by authorized users Use a firewall to lock out others Firewall – a network security system that prevents unauthorized access. Extranet Extends intranet by providing various levels of accessibility to authorized members of the public. 2005 Book

Intranet, Extranet, Internet
Largest and most widely access network Numerous networks linked together through routers Router – device that connects different network technologies Devices use TCP/IP software to communicate Computers on the Internet are either clients or servers. A Client is sent information from the server. Interactive 2005 Book

Telecommunications The transmitting and receiving of data
Includes voice and video Requires a modem or adapter and a line or cable The speed of data transmission (sending) and receipt (receiving) is measured in Kbps (1000s of bits per second) or Mbps (millions of bits per second). 2005 Book

Telecommunications Options Conventional modem
Uses standard telephone lines to convert analog signals to digital data Conventional model – 56 Kbps – transmits at 28.2 Kbps and 36.6 Kbps and receives at 56 Kbps Slower access time DSL (Digital Subscriber Line) Uses standard telephone lines with data transmission up to 640 Kbps Data receipt is from 1.5 Mbps to 9 Mbps ADSL is most common form used. 2005 Book

Telecommunications Options Cable Modem Leased/Dedicated Lines
Transmits data through coaxial cable television network Transmission is from 2 Mbps to 10 Mbps Data receipt is from 10 Mbps to 36 Mbps Leased/Dedicated Lines Used by many business and schools Allow for a permanent connection – always active Cost is usually fixed monthly fee Example: T1 transmits data at Mbps ISDN (Integrated Services Digital Network) Digital telephone network Transmits up to 64 Kbps Requires use of an ISDN terminal adapter instead of a modem. 2005 Book

Internet Services: Web, E-mail, and Mailing Lists
World Wide Web (WWW) Most widely used Internet service Web browser Application that provides a graphical interface to present information in the form of a website. Blog (Weblog) Users post entries in a journal format Digital Signature A code that is attached to an electronic message to verify the authenticity of a website or message. 2005 Book

– electronic mail Sending of receiving of messages and computer files over a communications network. Requires sofware user name host or top-level domain domain name 2005 Book

Rules when composing Use manners and properly address people Mrs, Mrs… Be concise Be professional Spelling & grammar Re-read before sending Fill in To box last to be sure it doesn’t send before you are finished. 2005 Book

is NOT private Etiquette Send message through your account only Use appropriate subject matter and language Be considerate of other’s beliefs and opinions Mailing list server Server that manages mailing lists for groups of users 2005 Book

Finding Information on the Web and Downloading Files
Search engine Program that searches a database of web pages for keywords and then lists hyperlinks to page that contain those keywords Commonly used Yahoo, Google, MSN, AOL, Excite, Ask Jeeves… Search criteria Can include single words or phrases that are used by the engine to determine a match (A web page that contains the search criteria) More specific is better 2005 Book

Limit the number of matches using Boolean logic in search criteria + (plus sign) Search for pages that contain all specified words Florida + hotel OR Search for pages that contain any one of the words - (minus sign) Used to exclude unwanted pages 2005 Book

Subject Tree Web directory A list of sites separated into categories Allow user to narrow down the subject and display a list of appropriate hyperlinks Downloading Process of copying a file from a website to the user’s computer. 2005 Book

Must give a citation if you use a website in a report, essay, or other document. Citation for material located at a website Author’s last name. First Name MI. Site Title. Access date. Organization name. <URL> 2005 Book

Internet Privacy Issues
Online profiling Marketing technique where data is collected about customers visiting a website Cookie Text file created by the server computer when a user enters information into a website. Web beacons (web bugs or pixel tags) Tiny, transparent graphics located on web pages or in message that are used in combination with cookies to collect data about web page users or senders Privacy Policy Legally binding document that explains how any personal information will be used. 2005 Book

The Social & Ethical Implications of Computers
Information Age How historians refer to the present Due to the computer’s ability to store and manipulate large amounts of information Netiquette Do not attempt to access the account of another user without authorization Do not share your password, and change it periodically Use appropriate subject matter and language, and be considerate of other people’s beliefs and opinions.

Privacy Ethical issue Computers record transactions, calls, etc. These records can be used to learn a lot about you. Because of privacy issues, many laws have been passed.

Fair Credit Reporting Act of 1970 Addresses data collection by credit, insurance and employment agencies Gives individuals the right to see information maintained about them Restricts who may access credit files to only those with a court order or the written permission of the individual whose credit is being checked.

Privacy Act of 1974 Restricts the way in which personal data can be used by federal agencies Individuals must be permitted access to information stored about them and may correct any information that is incorrect. Agencies must insure both the security and confidentiality of any sensitive information.

Financial Privacy Act of 1978 Requires government authorities have a subpoena, summons or search warrant to access an individual’s financial records When records are released, the financial institution must notify the individual of who has had access to them.

Electronic Communications Privacy Act of 1986 (ECPA) Makes it a crime to access electronic data without authorization Prohibits unauthorized release of such data

Electronic Freedom of Information Act of 1996 Requires federal government agencies to make certain agency information available for public inspection Designed to improve public access to agency records

Children’s Online Privacy Protection Act of 1988 (COPPA) Requires commercial websites that collect personal information from children under the age of 13 to obtain parental consent. 2005 Book

Safety and Freedom through Encryption Ace of 1999 (SAFE) Gives Americans the freedom to use any type of encryption to protect their confidential inforamtion. Prohibits the government from monitoring people’s communications without their knowledge or consent.

Provide Appropriate Tools Required to Intercept and Obstruct Terrorism (PATRIOT) Act of 2001 Gives law enforcement the ability to monitor individual’s and web activity 2005 Book

Protecting Computer Software and Data
Piracy Illegal copying of software Current issue Willful interference with or destruction of data Virus A program that is designed to reproduce itself by copying itself into other programs stored on a computer without the user’s knowledge Use antivirus software and update frequently Virus check attachments and diskettes

Internet Acceptable Use Policy
Use appropriate language Do not reveal personal address or phone numbers Do not access, upload, download, or distribute inappropriate materials Do not access another’s account Use of the network for private business is prohibited. Only administrator installed software may be used on the computers. Adding, deleting or modifying installed software is not permitted. 2005 Book

The Social & Ethical Implications of Computer Use
As an information society, we must consider both the social and ethical implications of our use of computers Ergonomics The science that studies safe work environments. Power & paper waste – environmental concerns Employee monitoring Issues with computers in the workplace Invasion of privacy Identity theft 2005 Book

Copyright Protection of digital information NET (No Electronic Theft) Act of 1997 Protects against copyright infringement Piracy Illegal copies being distributed Virus Program or series of instruction that can replicate without the user’s knowledge Trojan Horse Appears as something else Worm Program that is able to reproduce itself over a network 2005 Book

Antivirus programs Install on computers to detect and remove code before it can replicated or damage data Precautions to take Update virus software Do not open attachments without scanning. Crackers, Hackers Illegal act to gain access to large computer systems to perform acts of vandalism. Electronic Communications Privacy Act of 1986 makes it a federal offense. Most networks have a firewall to prevent this type of access. Phishing Act of sending an to a user falsely claiming to be a legitimate business in an attempt to trick the user into revealing personal information that could be used for crimes like identity theft. 2005 Book

The Ethical Responsibilities of the Programmer/IT Professional
There is a strong ethical burden on the programmer to insure the reliability of the computer software. Be cautious when allowing computers to replace humans where judgment is crucial. IT professional has responsibilities that relate to system reliability. Must use appropriate tools/methods to test and evaluate programs before distribution. Ensure the reliability of the software Ensure accurate data retrieval 2005 Book

Computers & Programming Languages

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