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Transcript
Introduction to Computers and Programming Professor Avi Rosenfeld Introduction to Computers and Programming - Class 1 1 Administrative Details Course home page is at www.cs.nyu.edu/courses/fall01/V22.0002-001/index.htm Syllabus is accessible from the home page There will be six homeworks, two midterms and a final There will be OPTIONAL homeworks given more frequently Office hours are on Wednesday, 8:30-9:30 A.M., room 419 CIWW, and by appointment Introduction to Computers and Programming - Class 1 2 About Me Email: [email protected] Yeshiva University Web Page: http://www.yu.edu/faculty/arosnfld/ Introduction to Computers and Programming - Class 1 3 Important Information See the syllabus for more details on homework, midterms and the final Class participation is important and will help your final grade To proceed with further computer science courses in the undergraduate division, you *MUST* achieve a grade of C or better-NO EXCEPTIONS CAN BE MADE Introduction to Computers and Programming - Class 1 4 Introduction The purpose of this course is to teach you about computing, but particularly, programming in C (a powerful, widely-used programming language see Linux). The goal of the course is to introduce you to the world of C.S. and to give you the ability to program independently. Introduction to Computers and Programming - Class 1 5 What is a Computer? Device capable of performing computations and enacting logical decisions Computers process data through sets of instructions called computer programs Programs guide the computer through actions as specified by people called computer programmers. Introduction to Computers and Programming - Class 1 6 Elements of a Computer Input devices (files, keyboards, mice, etc.) Output device (files, screen, printers, etc.) Memory (video, cache, flash, etc.) Arithmetic and logic unit (ALU) data process Central Processing Unit (CPU) control Secondary Storage (e.g. hard disk, floppy) Introduction to Computers and Programming - Class 1 7 Hardware vs. Software Hardware – Physical Components Software – Logical Instructions Firmware – Logical Instructions imprinted on physical Components Introduction to Computers and Programming - Class 1 8 How Does a Computer “think”? Transistors form switches that are in “on” or “off” states. The Pentium 4 chip has over 42 million transistors. Each transistor creates one bit. 8 bits create one byte Introduction to Computers and Programming - Class 1 9 Why are Bytes Important? ASCII (American Standard Code for Information Interchange) tables Unicode addresses the ASCII limitations http://www.asciitable.com/ Introduction to Computers and Programming - Class 1 10 Evolution of the Computer Early computers used batch processing – one job (program) at a time Very inefficient, sometimes days till output produced Often automation techniques still run in batch. Terminals used – “dumb” client Operating systems (OS’s) were first developed to handle switching between jobs Multitasking Multithreading Introduction to Computers and Programming - Class 1 11 Personal Computing In 1977, Steve Jobs and Steve Wozniak popularized personal computing with the Apple (proprietary equipment) In 1981, IBM introduced the IBM Personal Computer (PC), using “off-the-shelf” components Today’s top PC’s are as powerful as the million dollar machines of only ten years ago. Aren’t “dumb” terminals. Introduction to Computers and Programming - Class 1 12 Programming Languages Machine language Hardware-dependent, cumbersome manipulation of series of numbers (1’s and 0’s) Assembly language, e.g. LOAD BALANCE ADD TAX STORE TOTAL High-level languages (compiled or interpreted) Pascal, Lisp, Ada, Java, Basic, C, C++, etc. Introduction to Computers and Programming - Class 1 13 The C Programming Language C was originally created in 1972 by Dennis Ritchie at Bell Labs= C is a relatively low-level high-level language; i.e. deals with numbers, characters, and memory addresses Introduction to Computers and Programming - Class 1 14 Functions (“verbs” to Deitel) C programs consist of modules called functions Functions are groups of instructions that operate on data to produce and often return results Known in other languages as methods, procedures, subs, among others Introduction to Computers and Programming - Class 1 15 Objects (“Nouns” to Deitel) Object-oriented programming seeks to model the behavior of objects There are data and operations (functions) that work on just that data Benefits Reusability Quicker development Easier maintenance Introduction to Computers and Programming - Class 1 16 Structured Programming Disciplined approach to writing programs that are clear, correct and easy to maintain and modify The goal of this course is to make you into structured programming. Introduction to Computers and Programming - Class 1 17 Creating Programs in C Six basic steps Edit Preprocess Compile Link Load Execute Introduction to Computers and Programming - Class 1 18 Editor Used to create the program and store it on disk (secondary storage) C programs should be saved with a .c extension Introduction to Computers and Programming - Class 1 19 Preprocessor Handles various manipulations before compiling, including Inclusion of additional specified files (e.g. stdio.h, stdafx.h) Text replacement Results in more efficient, clearer and less unwieldy code Introduction to Computers and Programming - Class 1 20 Compiler Translates the saved program file to machine language (a/k/a object code) and saves it to a file Introduction to Computers and Programming - Class 1 21 Linker Links object code from any additional specified files into appropriate places in your code Produces a file that is an executable image of the linked object code and stores it on the disk Introduction to Computers and Programming - Class 1 22 Loader Puts the executable image (instructions) from the disk into primary memory Introduction to Computers and Programming - Class 1 23 Execute CPU takes each instruction in primary memory and executes it CPU may also store new data values as program executes Introduction to Computers and Programming - Class 1 24