Transcript Introduction: chap. 1 - NYU Computer Science Department

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
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About Me
 Email: [email protected]
 Yeshiva University Web Page:
http://www.yu.edu/faculty/arosnfld/
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Programming - Class 1
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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
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Programming - Class 1
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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.
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Programming - Class 1
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What is a Computer?
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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.
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Programming - Class 1
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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)
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Programming - Class 1
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Hardware vs. Software
 Hardware – Physical Components
 Software – Logical Instructions
 Firmware – Logical Instructions imprinted
on physical Components
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Programming - Class 1
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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
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Programming - Class 1
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Why are Bytes Important?
 ASCII (American Standard Code for
Information Interchange) tables
 Unicode addresses the ASCII limitations
 http://www.asciitable.com/
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Programming - Class 1
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Evolution of the Computer
 Early computers used batch processing – one job
(program) at a time
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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
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Multitasking
Multithreading
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Programming - Class 1
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Personal Computing
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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.
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Programming - Class 1
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Programming Languages
 Machine language
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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.
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Programming - Class 1
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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
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Programming - Class 1
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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
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Programming - Class 1
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Objects (“Nouns” to Deitel)
 Object-oriented programming seeks to model
the behavior of objects
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There are data and operations (functions) that
work on just that data
 Benefits
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Reusability
Quicker development
Easier maintenance
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Programming - Class 1
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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.
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Programming - Class 1
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Creating Programs in C
 Six basic steps
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Edit
Preprocess
Compile
Link
Load
Execute
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Programming - Class 1
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Editor
 Used to create the program and store it on
disk (secondary storage)
 C programs should be saved with a .c
extension
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Programming - Class 1
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Preprocessor
 Handles various manipulations before
compiling, including
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Inclusion of additional specified files (e.g.
stdio.h, stdafx.h)
Text replacement
 Results in more efficient, clearer and less
unwieldy code
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Programming - Class 1
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Compiler
 Translates the saved program file to machine
language (a/k/a object code) and saves it to a
file
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Programming - Class 1
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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
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Programming - Class 1
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Loader
 Puts the executable image (instructions) from
the disk into primary memory
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Programming - Class 1
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Execute
 CPU takes each instruction in primary
memory and executes it
 CPU may also store new data values as
program executes
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Programming - Class 1
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