Chapter 0 Introduction Yonsei University 1 st Semester, 2012 Sanghyun Park

Outline  What is computer science?  What is an algorithm?  History of computing

What is Computer Science?  Computer science is the discipline that seeks to build a ________ ________ for such topics as computer design, computer programming, information processing, and algorithmic solutions of problems  A computer is the machine that performs _________ (provides computing capabilities to its users)  Computing is the execution of an “_________”

What is an Algorithm? (1/3)  A set of steps that defines how a task is performed  Formal definition: an _______ set of ___________, executable steps that define a __________ activity  Examples of algorithms  Operating a washing machine  Multiplication of 2 integers  Finding the greatest common divisor of two positive integers (Figure 0.2)

What is an Algorithm? (2/3)  A machine-compatible representation of an algorithm is called a _______  Representation of an algorithm so that it can be communicated to a ________  The process of developing a program is called ____________  Programming languages (C, C++, Java)  Programs, and algorithms they represent, are collectively referred to as ________, and the machine itself is _________

What is an Algorithm? (3/3)  If no algorithm exists for performing a task, then the task cannot be performed by a machine  Gödel’s _____________ theorem: some problems cannot be solved by algorithms

Central Role of Algorithms in Computer Science

History of Computing (1/9)  Abacus (almost 5,000 years ago)  First computing device. Position of ______ represents and stores data

History of Computing (2/9)  Represent data through mechanical _____ positioning  Pascal, Leibniz: Output achieved by observing the final gear positions  Babbage: Print values on paper  1645: Pascal ( ) makes “Pascaline”. Follow addition algorithm  1674: Leibniz ( ) designs “Stepped Reckoner”. A variety of arithmetic operations from which the user can select

History of Computing (3/9)  1832: Babbage ( ). Prototype of a difference engine (6 digit calculator using gear technology) Sequence of steps could be communicated to the machine in form of holes in paper cards (programmable). His assistant “Augusta Ada Byron” is often identified as world’s first __________  Herman Hollerith ( ) applied punch cards idea to speed up _________ in 1890 US Census. (Work led to the creation of ____)

History of Computing (4/9)  __________ 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 Clifford Berry complete a prototype 16-bit adder. This is the first machine to calculate using vacuum tubes

History of Computing (5/9)  1945: John von Neumann ( ) drafts a report describing the future computer eventually built as EDVAC (Electronic Discrete Variable Automatic Computer)  This is the first description of the design of a _____________ computer, and gives rise to the term “von Neumann computer”  1946: ENIAC (Electronic Numerical Integrator And Calculator). University of Pennsylvania

History of Computing (6/9)  Transistors, integrated circuits (IC)  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 __ at Bell labs  1976: Steve Jobs and Stephen Wozniak built a commercially viable home computer (established _____ company)

History of Computing (7/9)  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: Japan launches fifth generation computer focused on AI  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)

History of Computing (8/9)  1989: Intel’s microprocessor is introduced  1990: Microsoft introduces Windows 3.0  1993: 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  2002: Intel’s Pentium 4 processor offers speed up to 2.53 GHz

History of Computing (9/9)  New trends  DNA computing  Pervasive computing  Wearable computing  Quantum computing  Some references  Timeline of computing history (IEEE Computer) (  The history of computing (Virginia Tech) (