Introduction to Computers, Programs, and Python

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Introduction to Computers, Programs, and Python

• HI5100 Data Structures for BioInformatics
• Lesson 1

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• Man is still the most extraordinary computer of
  all.
• John F. Kennedy

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OBJECTIVES

• In this Lesson you will learn
• Roles of hardware and software in a computing
  system.
• What computer science might have to offer life
  sciences and health care industries.
• To differentiate different types of programming
  languages.
• Name of programming languages that are widely
  used.
• A little history of the Python language.
• Some basics of Python and the interpreter that
  executes programs written in the Python language.
• Historical background for UMLthe
  industry-standard object oriented system modeling
  language.
• Historical background for the Internet and the
  World Wide Web.
• To test-drive a simple Python program script.

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Lesson 1 Sections

• 1.1 What Is a Computer?
• 1.2 What is a Program?
• 1.3 What is Computer Science?
• 1.4 Hardware Basics
• 1.5 Historical Perspectives
• 1.6 Personal Computing, Distributed Computing and
  Client/Server Computing

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Lesson 1 Sections

• 1.7 Hardware Trends
• 1.8 Operating Systems
• 1.9 The Internet and the World Wide Web
• 1.10 Types of Programming Languages
• 1.11 High-Level Languages
• 1.12 Python

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What is a Computer?

• Device
• Stores and manipulates information
• Does this under the control of a changeable
  program
• Performs computations fast
• Performs yes/no decisions fast
• e.g., are two values equal?

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A Computer Transforms Information
info in
transformed info out
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What is Not a Computer?

• Calculator transforms information
• ATM machine transforms information
• Built to perform a single specific task
• Many task-specific electronic devices contain
  embedded computers

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What is a Computer?

• Its a device that executes changeable programs
• Part hardware devices such as keyboard, screen,
  mouse, hard drive, memory, DVD drive, processors,
  etc.
• Part software programs that run on a computer
• Word processing programs
• Email
• Browser
• Games
• Etc.

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What is a Computer Program?

• Step-by-step instructions that tell the computer
  what to do
• Software programs that run on a computer
• Word processing programs
• Email
• Browser
• Games
• Etc.

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Programming

• Process of creating software
• Since software controls the hardware, enabling it
  to complete tasks, it is important to all
  computer professionals
• Creative process
• Anyone can learn the basics
• Can be fun!

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Computer Science

• What can be computed?
• Anything that can be described by a step-by-step
  process that can be translated into a program
• Algorithm a step-by-step process for achieving
  some desired result
• Techniques design, analysis, experimentation

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Computing Science Life Science

• Describe life science processes for computability

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Six Logical Units

• Central processing unit
• Arithmetic and logic unit
• Memory unit
• Secondary storage unit
• Input unit
• Output unit

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Central Processing Unit

• CPU (lingo)
• Coordinates activities of the other units

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Arithmetic and Logic Unit

• ALU (lingo)
• Performs calculations (, -, , /)
• Decisions (compare two items in memory and decide
  if they are the same)

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Memory Unit

• Fast-access, low capacity (relatively), storage
• RAM, memory, primary memory, core memory, main
  memory are other terms used
• Volatile memory

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Secondary Storage Unit

• Slower access, more capacity, storage
• Not volatile
• Hard drives
• CD, DVD
• Memory stick
• Floppy disks (old technology)

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Input Unit

• Gets data and computer programs into the system
• Input devices
• Keyboard
• Mouse
• Scanner
• Microphone
• Etc.

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Output Unit

• Takes info from computer and transfers it to
  output devices
• Output devices
• Monitor
• Printer
• Network

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When You Start Software

• Instructions that comprise the program are copied
  from secondary storage into main memory (RAM)
• CPU begins running the program following a
  process of fetch-decode-execute
• Fetch get the next instruction from RAM
• Decode translate into machine actions
• Execute perform the action

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What is a Computer? Web Resources

• http//en.wikipedia.org/wiki/Computer

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Early Computing

• Before 1960
• Batch processing computers performing one task
  at a time
• Submit a job on punched cards, get output
  (printout) the next day
• Computer fills a room
• No PCs

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Early Operating Systems

• Before 1960
• Operating system software to make a computer
  easier to use
• Made computers able to do more jobs
• Multiprogramming
• Computers handle more than one job at a time

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Timesharing

• During the 1960s
• Multiple users access one large computer in
  another room through a terminal
• Keyboard and screen
• OS directs computer to handle one users job for
  a few seconds, then another, etc.

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Personal Computing

• 1970s
• Silicon chip technology
• Smaller computers
• Apple (1977)
• IBM (1981)
• Stand-alone computers on your desk
• Boot from floppy disk with OS on floppy
• Store work on floppy disks
• Share work by sharing floppy disks

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Distributed Computing

• Network stand-alone units together to facilitate
  sharing of work
• Local area networks (LAN)

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Client/Server Computing

• Server provides a common data store for multiple
  users
• File server
• Application server
• Web server
• Database server
• Client desktop computer uses data from the
  common data store on the server

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Hardware Trends

• Computer hardware costs have steadily decreased
  in relation to the capability of the devices
  purchased
• Moores Law Every year or two you can buy twice
  as much computing power for the same amount of
  money

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Microsofts Windows OS

• A number existed prior to the 1980s
• 1981 DOS (Disk Operating System)
• User types commands at a prompt telling OS what
  to tell the computer to do
• Doesnt need a mouse, just a keyboard
• 1990 Windows 3.0
• Graphical user interface (GUI)
• Not an OS, ran on top of DOS OS
• 1993 Windows NT OS
• Windows XP is based on Windows NT

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Other OS

• LINUX
• Free
• Open-source the source code is freely available
  to users who can modify it to suit their needs
• UNIX
• Proprietary (Bell Labs)
• Written in C programming language

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The Internet

• Global network of computers
• Started by DOD to connect computers of research
  universities
• E-mail was a popular technology on the early
  text-only internet

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World Wide Web

• Servers connected via the Internet can supply
  multimedia files to users
• Created in 1989
• Tim Berners-Lee of CERN invented HTML and
  communication protocols
• Computing and communication are combined via WWW
  and the Internet

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W3C

• World Wide Web Consortium
• Devoted to development of nonproprietary,
  interoperable technologies for the WWW
• Make WWW accessible to everyone regardless of
  disabilities, language, or culture
• Create standards called Recommendations
• www.w3.org

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XML

• Extensible Markup Language
• Separate content from presentation (markup with
  HTML)
• XML documents describe the meaning or purpose of
  data, not how it is supposed to look when you see
  it
• They are text documents, thus they can be
  processed by software on any hardware platform

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Types of Programming Languages

• Machine language
• Assembly language
• High-level language

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Machine Language

• The natural language of a specific machine
• Determined by the hardware design of the machine
• Machine dependent any given machine language can
  be used on only one type of computer
• Cumbersome for humans

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Machine Language Program Example

• Adds overtime pay to base pay
• Stores the result in gross pay

1300042774 1400593419 1200274027
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Assembly Language

• Use English-like abbreviations for strings of
  numbers
• Assembler a translator program that translates
  English-like assembly language statements into
  machine language

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Assembly Language Program Example

• Adds overtime pay to base pay
• Stores the result in gross pay
• More understandable, more like English

Load basepay Add overpay Store grosspay
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High-Level Language

• Single statements accomplish substantial tasks
• Instructions look almost like everyday English
  and/or math
• Syntax Precise form required for each statement
• Semantics precise meaning of each statement
• No ambiguity

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High-Level Language Statement Example
grossPay basePay overTimePay

• Adds overtime pay to base pay
• Stores the result in gross pay
• Understandable
• Looks like Algebra

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Popular High-Level Languages

• C
• C
• Java
• Visual C

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Other High-Level Languages

• Fortran (FORmula TRANslator)
• COBOL (Common Business Oriented Language)
• Pascal
• Ada
• Python

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Translator Program

• Converts from a high-level language or into
  machine language in one of two ways
• Compiling
• Interpreting

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Compiler versus Interpreter

• Compiler a translator program that converts
  high-level language into machine language
• Interpreter a program that executes high-level
  language directly one line at time
• Execution is slower than with a compiled program
• Scripting languages for the web are executed by
  an interpreter that is part of the browser

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Python

• Created in 1990s
• All Python releases are Open Source
• Go to http//www.opensource.org/ for the
  definition of Open Source
• Python Interpreter
• Interprets code written in Python syntax
• Saves time during development phase

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Python IDLE

• Integrated Development Environment
• Software to facilitate development of
  applications

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Summary

• Computers are versatile because they are
  programmable
• 40 years of development have led to where we are
  today

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End of Slides for Lesson 1

• HI5100 Data Structures for BioInformatics
• Lesson 1