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COSC1557: Introduction to Computing

COSC1557: Introduction to Computing. Haibin Zhu, PhD. AssistProfessor Department of Computer Science Nipissing University (C) 2002. Instructor. Haibin Zhu, Ph. D. Assistant Professor, Department of CS and Math, Nipissing University Room: A124A Ext.: 4434 Email: haibinz@nipissingu.ca

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COSC1557: Introduction to Computing

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  1. COSC1557: Introduction to Computing Haibin Zhu, PhD. AssistProfessor Department of Computer Science Nipissing University (C) 2002

  2. Instructor • Haibin Zhu, Ph. D. • Assistant Professor, Department of CS and Math, Nipissing University • Room: A124A Ext.: 4434 • Email: haibinz@nipissingu.ca • URL: http://www.nipissingu.ca/faculty/haibinz • Office Hour: Mon.–Fri. 2:30pm-4:30pm, and by appointment

  3. Nature and uses of the computer-, algorithms-, number systems, information representation; and organization, with an overview of computer hardware and software, computing systems and major applications. Ethical and societal issues arc discussed. An introduction to high-level languages with an emphasis on writing programs in C++. Course Description

  4. Textbook and references • Textbook:Joel Adams and Larry Nyhoff, C++: An Introduction to Computing, 3/e. Prentice Hall, © 2003 ISBN: 0-13-091426-6 • Lecture Notes on http://cs.calvin.edu/books/c++/intro/3e/PPSlides/ • Student Supplements: CD-Lab Manual (ISBN: 013080648X) • Some Lab: http://cs.calvin.edu/books/c++/intro/3e/HandsOnC++/

  5. Beginning Snapshots Chapter 0

  6. Objectives • Give an overview of computer science • Show its breadth • Provide context for computer science concepts • Events from the past • Describe basic components, organization of a computer

  7. Algorithms and Data Structures Architecture Artificial Intelligence and Robotics Database and Information Retrieval Human-Computer Communication Numerical and Symbolic Computation Operating Systems Programming Languages Software Methodology and Engineering Social and Professional Context Areas of Computer Science

  8. Important Concepts in Computer History • The mechanism of arithmetic • The stored program • The graphical user interface • The computer network

  9. First-Generation Computers • Vacuum tube computers 1945-1956 • ENIAC 1943-1946 • John Von Neumann's"First Draft of a Report onthe EDVAC" 1945 • First bug in a computer 1945 • UNIVAC 1951

  10. Second Generation Computers • Used transistors 1956-1963 • FORTRAN 1957 • IBM 7090 1958 LISP • COBOL 1960 ALGOL 60

  11. Third-Generation Computers • Chips and Integrated Circuits 1964-1971 • The IBM System/360 1964 • The PDP-8 1965 • Douglas Englebart: the mouse, Two-D display, editing, hypermedia, 1968 Pascal • Ken Thompson: UNIX 1969 ARPANET – The beginning of the Internet

  12. Fourth-Generation Computers • Intel 4004 Chip 1971 • Dennis Richie: C 1973 • Ethernet • Court rules Atanasoff was legal inventor of first electronic digital computer • Altair, BASIC, Apple 1 1974 • Apple II, Cray 1, Apple Corp.Microsoft Corp. 1976 • IBM PC 1981

  13. Fourth-Generation Computers • Bjarne Stroustrup: C++ 1983 Novell announces NetwareTCP/IP • Macintosh 1984 • Windows 1985 • Intel 386 Chip 1986 • Tim Berners—Lee: WWW 1991 • Linux 1992

  14. Fourth-Generation Computers • Pentium chips, Power PC chip 1993 MOSAIC, Apple Newton • Netscape Navigator 1.0, Yahoo! 1994Palm computing • James Gosling: JAVA 1995Windows 95, Internet Explorer,Internet goes commercial • Windows 98, Apple's IMAC 1998Microsoft's court case

  15. Fourth-Generation Computers • Y2K Problem, Powermac G4 1999 • Windows 2000 20001 GHZ processors • Mac OS X 2001Windows XP • Quantum Computer 2002

  16. Graphical User Interface • Command line interface required precise and cryptic commands • Xerox PARK had developed GUI prototype in 1972 • Steve Jobs saw it several years later and used new hardware capabilities to implement • GUI makes computer easy to use

  17. Network • Defn: Two or more computers connect to exchange resources • Processing power • Storage • Access to a printer • Software resources • Messages

  18. Network • Time sharing in early 1960s • Users communicate with host computer • ARPANET connected research center computers in 1969 • Eventually developed into Internet • Local Area Network hardware and operating systems developed late 1970s • ISPs now affordable, widely available for even home computers

  19. Computer Organization Hardware and Software Calvin College

  20. Computing Systems Computers have two kinds of components: • Hardware, consisting of its physical devices (CPU, memory, bus, storage devices, ...) • Software, consisting of the programs it has (Operating system, applications, utilities, ...)

  21. Hardware: CPU Central Processing Unit (CPU): • the “brain” of the machine(?) • location of circuitry that performs arithmetic and logical ML statements • measurement: speed (roughly) in megahertz (millions of clock-ticks per second) • examples: Intel Pentium(PI, PII, PIII, P4), AMD K6, Motorola PowerPC, Sun SPARC,

  22. Hardware: RAM Random Access Memory (RAM) • “main” memory, which is fast, but volatile... • analogous to a person’s short-term memory. • many tiny “on-off” switches: for convenience • “on” is represented by 1, “off” by 0. • each switch is called a binary digit, or bit. • 8 bits is called a byte. • 210 bytes =1024 bytes is called a kilobyte (1K) • 220 bytes is called a megabyte (1M).

  23. Hardware (Disk) Secondary Memory (Disk): • Stable storage using magnetic or optical media. • Analogous to a person’s long-term memory. • Slower to access than RAM. • Examples: • floppy disk (measured in kilobytes) • hard disk (measured in gigabytes (230 bytes)) • CD-ROM (measured in megabytes), ...

  24. Hardware: the Bus The Bus: • Connects CPU to other hardware devices. • Analogous to a person’s spinal cord. • Speed measured in megahertz (like the CPU), but typically much slower than the CPU... • The bottleneck in most of today’s PCs.

  25. Hardware: Cache While accessing RAM is faster than accessing secondary memory, it is still quite slow, relative to the rate at which the CPU runs. To circumvent this problem, most systems add a fast cache memory to the CPU, to store recently used instructions and data. (Assumption: Since such instructions/data were needed recently, they will be needed again in the near future.)

  26. CPU Main Memory Secondary Memory cache Bus Hardware: Summary Putting the pieces together: Programs are stored (long-term) in secondary memory, and loaded into main memory to run, from which the CPU retrieves and executes their statements.

  27. Disk CPU RAM Cache OS Bus Software: OS The operating system (OS) is loaded from secondary memory into main memory when the computer is turned on, and remains in memory until the computer is turned off.

  28. Software: OS The OS acts as the “manager” of the system, making sure that each hardware device interacts smoothly with the others. It also provides the interface by which the user interacts with the computer, and awaits user input if no application is running. Examples: Windows 2000, Windows XP, Windows-NT, UNIX, Linux, Solaris, MacOS, ...

  29. Software: Applications Applications are non-OS programs that perform some useful task, including word processors, spreadsheets, databases, web browsers, C++ compilers, ... Example C++ compilers/environments: • CodeWarrior (MacOS, Win95, WinNT, Solaris) • GNU C++ (UNIX, Linux) • Turbo/Borland C++ (Win95, WinNT) • Visual C++ (Win95, WinNT)

  30. Software: User Programs Programs that are neither OS programs nor applications are called user programs. User programs are what you’ll be writing in this course.

  31. Disk CPU RAM Cache OS App Bus Putting it all together Programs and applications that are not running are stored on disk.

  32. Disk CPU RAM Cache OS OS App App Bus Putting it all together When you launch a program, the OS controls the CPU and loads the program from disk to RAM.

  33. Disk CPU RAM Cache OS App App App Bus Putting it all together The OS then relinquishes the CPU to the program, which begins to run.

  34. The Fetch-Execute Cycle As the program runs, it repeatedly fetches the next instruction (from memory/cache), executes it, and stores any results back to memory. Disk CPU RAM Cache OS App App App Bus That’s all a computer does: fetch-execute-store, millions of times each second!

  35. Programming

  36. What is Programming? A sequence of statements that instruct a computer in how to solve a problem is called a program. The act of designing, writing and maintaining a program is called programming. People who write programs are called programmers.

  37. What kinds of statementsdo computers understand? A computer only understands machine language statements. A machine language statement is a sequence of ones and zeros that cause the computer to perform a particular action, such as add, subtract, multiply, ...

  38. Machine Language (ML) ML statements are stored in a computer’s memory, which is a sequence of switches. For convenience of representation, an “on” switch is represented by 1, and an “off” switch is represented by 0. ML thus appears to be binary (base-2): 0010111010110101

  39. Early Computers ... required a programmer to write in ML... • Easy to make mistakes! • Such mistakes are hard to find! • Not portable -- only runs on one kind of machine! Programming was very difficult!

  40. Assembler ADD 0010111010110101 A Bright Idea Devise a set of abbreviations (mnemonics) corresponding to the ML statements, plus a program to translate them into ML. The abbreviations are an assembly language, and the program is called an assembler.

  41. Assembly Languages Allowed a programmer to use mnemonics, which were more natural than binary. • Much easier to read programs • Much easier to find and fix mistakes • Still not portable to different machines

  42. High Level Languages Devise a set of statements that are close to human language (if, while, do, ...), plus a program to translate them into ML. The set of statements is called a high level language (HLL) and the program is called a compiler.

  43. 1010110011110101 0000000000010000 0010111010110101 0000000000010010 0010111011111101 0000000000010100 Compiler z = x + y; HLL Compilers Where an assembler translates one mnemonic into one ML statement, a HLL compiler translates one HLL statement into multiple ML statements.

  44. HLLs High level languages (like C++) are • Much easier to read programs • Much easier to find and fix mistakes • Portable from one machine to another (so long as they keep to the language standard).

  45. Objectives in Programming A program should solve a problem: • correctly (it actually solves the problem) • efficiently (without wasting time or space) • readably (understandable by another person) • in a user-friendly fashion (in a way that is easy for its user to use).

  46. Summary A computer has two kinds of components: • Hardware: its CPU, RAM, Disk(s), ... • Software, its OS, Applications, and User Programs. There are “levels” to computer languages: • ML consists of “low” level binary statements, that is hard to read, write, and not portable. • Assembly uses “medium” level mnemonics: easier to read/write, but not portable. • C++ is a “high” level language that is even easier to read/write, and portable.

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