Chapter 0Introduction

Yonsei University

1st 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 inComputer 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 (1623-1662) makes “Pascaline”.

Follow addition algorithm 1674: Leibniz (1646-1716) designs “Stepped Reckoner”.

A variety of arithmetic operations from which the user can select

History of Computing (3/9) 1832: Babbage (1792-1871).

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 (1860-1929) 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 (1903-1957) drafts a report

describing the future computer eventually built as EDVAC (Electronic Discrete Variable Automatic Computer)

This is the first description of the design ofa _____________ 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 Wozniakbuilt 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 80486 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)

(http://www.computer.org/computer/timeline/) The history of computing (Virginia Tech)

(http://ei.cs.vt.edu/~history/)