Goals

• Describe the layers of a computer system
• Describe the concept of abstraction and its relationship to computing
• Describe the history of computer hardware and software
• Describe the changing role of the computer user
• Distinguish between systems programmers and application programmers
• Distinguish between computing as a tool and as a discipline

Computing Systems

• Some definitions
  • Computer- a programmable electronic device that can store, retrieve and process information.
  • Computer Hardware - the physical elements that make up a computer
  • Computer Software - a collection of programs that provide instructions that a computer executes
  • Data - information in a form that the computer can use.
  • Computing System - Hardware, Software, and data which interact to solve problems.
• Note all three pieces are important.
• Our authors would really like us to
  • Gain a broad understanding of how computing systems work
  • Develop an understanding of the evolution of modern computing systems
  • Give you sufficient information to decide if computing is for you.
• Layers of a computing system
  • Computing Systems, say our authors, are like onions (and ogres)
    • They have layers
    • 
    • You don't eat entire onions, you eat individual layers
      • They propose to do the same thing with a computing system
      • Study each of the different levels one at a time
      • There are some basic principles at each layer
      • When we bring them together, we get the big picture
    • Information
      • At one level a collection of 0 and 1
      • or Binary Digits (BITS)
      • We will study binary, and two other number systems as well (Chapter 2)
      • These digits are used to encode data, or information
      • We will discuss how this is done in Chapter 3
    • Hardware
      • The bits of junk that make up the computer
      • Starting with a transistor and gates
      • Circuits, and components
      • Chapters 4 and 5
      • Computer Architecture, Engineering, Physics
    • Programming Layer
      • A superlayer (multiple smaller layers)
      • Machine Language (Ch 7)
      • Assembly Language (Ch 7)
      • Higher Level Languages (Ch 8)
      • Problem Solving (Ch 6)
      • Data Structures (Ch 9)
      • Classes
        • Assembly
        • Principles of Programming (I,II)
        • VB
        • Compilers
        • Data Structures and Algorithms
    • OS Layer
      • Windows, Linux, VMS, ...
      • What makes it so we can use the hardware
      • a program that manages the resources of a computer
      • Chapters 10, 11
      • Operating Systems, Principles of Computer Operations
    • The Application Layer
      • The programs that we use
      • Spreadsheets, Databases, Games, ...
      • Simulations - weather prediction models
      • Many classes in many disciplines
      • Chapters 12, 13, 14
    • The Communications Layer
      • Networking
      • The hardware and protocols (ch 15)
      • And the applications (ch 16)
      • Web Development, Networking
    • And finally, what Can't computers do
      • Chapter 17
      • Automata
  • Details
    • There are lots of them.
    • This is a lifetime study?
    • A merry-go-round
• Abstraction
  • What is it?
  • A model that removes complex details
  • Model - moving into a new apartment, how do you plan this.
    • Bunch of big people to pick stuff up and move it around?
    • Paper cutout?
    • ???
    • What works
    • What doesn't
  • The ability to think abstractly and to form abstractions
  • Apparently we can have 7 +/- 2 bits of information in our short term memory at one time
  • If we can't abstract, we get "lost in the details"
  • This is important
    • When using a program, we don't care about how it is run/written
    • When writing a program we don't care how the data is stored
    • When ...
• Next A history of computing
• Please read Chapter 1
• Please read the Ethical issues on page 27-29