Lecture 1: 8/27/2002CS149D Fall CS149D Elements of Computer Science Ayman Abdel-Hamid Department of Computer Science Old Dominion University Lecture 1: 8/27/2002

CS149D Fall Outline What is Computer Science? What is an algorithm? What is a computer? history of Computing (not comprehensive!)

Lecture 1: 8/27/2002CS149D Fall What is Computer Science? Computer Science is the discipline that seeks to build a scientific foundation for such topics as computer design, computer programming, information processing, and algorithmic solutions of problems. Computing is the execution of an “algorithm” A computer is a machine that performs computing (provides computing capabilities to its users)

Lecture 1: 8/27/2002CS149D Fall What is an Algorithm? A set of steps that define how a task is performed Formal definition: An ordered set of unambiguous, executable steps that define a terminating activity. Examples of algorithms 1.Operating a washing machine 2.Multiplication of 2 integers 3.Making an apple pie

Lecture 1: 8/27/2002CS149D Fall A machine-compatible representation of an algorithm is called a program If no algorithm exists for performing a task, then the task can not be performed by a machine Programs and algorithms they represent are collectively referred to as Software, the machine itself is Hardware Representation of an algorithm so that it can be communicated to a machine Programming Languages (C, C++, Java, …)

Lecture 1: 8/27/2002CS149D Fall Computing Storage A Computer Input Output Five classic components of a computer: Input, Output, Memory, Data path, Control Manual Punch cards TapesKeyboardMouse Gear Position DisplayCardsPaper Processor Gears, vacuum tubes, memory transistors Mechanical units Steam engines Integrated circuits

Lecture 1: 8/27/2002CS149D Fall Role of Abstraction Think about a complex computer system using various levels of details At each level, identify components whose internal characteristics are ignored. Focus on component interaction, and how components can be used to construct higher-level components Distinction between external properties of a component and the internal details of the component instruction is known as abstraction Examples of abstraction Driving a car, sending , printing a document

Lecture 1: 8/27/2002CS149D Fall History of Computing 1/8 Abacus (almost 5,000 years ago) First computing device. Position of bead represents a stored value Data storage system. Combined with a human to create a complete computer

Lecture 1: 8/27/2002CS149D Fall History of Computing 2/8 Technology of gears Represent data through gear positioning with data being input mechanically to establish gear positions Pascal, Leibniz: Output achieved by observing final gear positions Babbage: Print values on paper 1645: Pascal (1623 – 1662) makes “Pascaline”. Follow addition algorithm 1674: Leibniz (1646 – 1716) designs his "Stepped Reckoner“. A variety of arithmetic operations that the user can select from

Lecture 1: 8/27/2002CS149D Fall History of Computing 3/8 1832: Babbage (1792 – 1871). Prototype of a difference engine (6 digit calculator using gear technology) Sequence of steps the machine was to perform could be communicated to the machine in form of holes in paper cards (programmable). His assistant “Augusta Ada Byron” identified as world’s first programmer Herman Hollerith (1860 – 1929) applied punched cards idea to speed up tabulation in 1890 US Census. (work led to creation of IBM)

Lecture 1: 8/27/2002CS149D Fall History of Computing 4/8 Electronics supplement mechanical devices (electronically controlled mechanical relays) 1940: Electromechanical machine of George Stibitz at Bell laboratories (Model I relay calculator) 1944: Mark I, Harvard University with a group of IBM engineers (first widely known programmable calculator) Vacuum Tubes 1939: John V. Atanasoff and graduate student Clifford Berry, of Iowa State College (now the Iowa State University), Ames, Iowa, complete a prototype 16-bit adder. This is the first machine to calculate using vacuum tubes.

Lecture 1: 8/27/2002CS149D Fall History of Computing 5/8 1945: John von Neumann ( ), drafts a report describing the future computer eventually built as the "EDVAC" ("Electronic Discrete Variable Automatic Computer“) this is the first description of the design of a stored-program computer, and gives rise to the term "von Neumann computer". 1946: ENIAC (Electronic Numerical Integrator and calculator). University of Pennsylvania

Lecture 1: 8/27/2002CS149D Fall History of Computing 6/8 Transistors, integrated circuits (IC) 1954: Texas Instruments announces the start of commercial production on silicon transistors. 1958: At Texas Instruments, Jack Kilby completes building the first integrated circuit (IC), containing five components on a piece of germanium half an inch long and thinner than a toothpick. 1972: Dennis Ritchie develops C at Bell labs (predecessor was named B) 1976: Steve Jobs and Stephen Wozniak built a commercially viable home computer (established Apple company) 1977: Bill Gates and Paul Allen found Microsoft 1981: IBM introduces first desktop computer called Personal Computer “PC”, with operating system developed by Microsoft 1982: Time Magazine names computer “Man of the Year”

Lecture 1: 8/27/2002CS149D Fall History of Computing 7/8 1982: Japan launches fifth generation computer focused on artificial intelligence 1984: CD-Rom introduced by Sony and Philips 1985: C++ (object-oriented extension to C) issued from Bell labs 1989: Tim Berners-Lee proposes a World Wide Web project to CERN (European Council for Nuclear Research) 1989: Intel’s microprocessor is introduced 1990: Microsoft introduces Windows : Intel’s Pentium processor is introduced 1994: Netscape’s first browser becomes available 1995: Java is released from Sun Microsystems 1996: Intel’s Pentium Pro processor is announced 1998: Microsoft releases Windows 98

Lecture 1: 8/27/2002CS149D Fall History of Computing 8/8 2002: Intel’s Pentium 4 processor offers speeds up to 2.53 GHz New Trends DNA computers (What is a DNA computer)What is a DNA computer Pervasive computing (from IBM)from IBM Wearable computing (A nice web site, definition)A nice web sitedefinition Quantum computing (The Quantum computer)The Quantum computer Some References Timeline of Computing History Timeline of Computing History (IEEE Computer) The History of computing The History of computing (Virginia Tech) Chronology of historical events in Computing Chronology of historical events in Computing (Hofstra University)