CS 177 Recitation

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CS 177 Recitation

• Aug 25, 2006 Week 1

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Important Things to Remember

• Course Webpage www.cs.purdue.edu/cs177
• Course Recitation slides will be posted here.
• Projects will be posted there.
• Contact details of all TAs.

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What are Computers?

• What is a computer?
• Device that receives, stores, and processes
  information
• What are some different types of computers?
• Supercomputers, Desktop, Laptop, Palmtop
• What is the main difference between them?
• Size, speed, memory, problems solved

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Hardware vs. Software

• What is hardware?
• The physical components of a computer (hard disk,
  processor, mouse, keyboard, monitor, etc).
• What is software?
• The programs that are written to make the
  computer do something interesting.
• What are computer specs?
• The capabilities of a computer. For example, how
  much memory, processor speed, hard disk space,
  etc.

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The von Neumann Architecture

• What are the 3 essential components of the von
  Neumann architecture?
• Input/Output devices allow the user to interact
  with the computer
• Stores data and programs in memory.
• Central Processing Unit (CPU) performs
  instructions in program to process information
• Which of the three components was a major change?
• Storing programs in memory (before was only data)

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Central Processing Unit

• What is the CPU?
• The brain of the computer. Performs
  instructions to process information.
• What unit is used to measure CPU speed these
  days?
• Gigahertz (GHz)
• What does a 2.3 GHz processor mean?
• The processor can execute roughly 2.3 billion
  instructions per second.

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Central Processing Unit Cont.

• What is an instruction?
• A simple operation the CPU can perform (add two
  numbers together, move this data over here, check
  if this number is zero or not)
• How do computers do such complex stuff with such
  simple commands?!
• Speed, they do so many that the result seems very
  complex.

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Memory

• What is memory?
• The place where the CPU stores and fetches data
  and instructions.
• How are the data and instructions stored?
• In binary (ones and zeros). Each digit is a
  bit.

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Memory Cont.

• What basic unit is used to represent memory
  capacity?
• The byte 8 bits (28 256 possible values)
• What does 512MB RAM mean?
• Roughly 512 million bytes of memory.
• What makes a computers RAM better?
• Faster read/write time, more space (i.e. bytes)

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Memory Cont.

• What types of memory are there?
• Main fast and expensive
• Secondary slower, but cheaper
• What are some examples of main memory?
• RAM, cache (memory that is saved for faster
  access the next time)
• What are some examples of secondary memory?
• Hard disk, Compact Disk (CD), flash drive, floppy
  disk

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Memory Cont.

• What is the difference between permanent and
  volatile memory?
• Volatile memory is gone when the computer is
  turned off, while permanent memory stays around.
• What are some examples of volatile memory?
• RAM, cache (main memory)
• What are some examples of permanent memory?
• Hard disk, Compact Disk (CD), flash drive, floppy
  disk (secondary memory)

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Software

• What are programs?
• Sequence of instructions that, when executed, do
  something hopefully useful.
• What are some examples of programs?
• Microsoft Word, Wordpad (word processors)
• Internet Explorer, Mozilla Firefox (browsers)
• Windows Media Player, Winamp, RealPlayer (media
  players)
• World of Warcraft, The Sims, Halo (games)
• Gmail, Hotmail, Purdue Webmail (email)
• Facebook, mySpace, LinkedIn (web apps)

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Operating Systems

• What is the operating systems main task?
• Controls access to system resources by programs
  (memory, CPU, etc.)
• What are some examples of Operating Systems?
• Windows XP, Linux, UNIX
• How are they different?
• User-friendliness, security, stability

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The Internet WWW

• What is the Internet?
• The global interconnection between computers
  (network) that supports communication.
• What is the WWW?
• An application of the Internet that allows
  interlinking of documents and resources.
• What are some other services available through
  the Internet?
• Email, Video Conferencing, Multiplayer Gaming

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The Internet WWW Cont.

• What is a protocol?
• The rules that govern communication between two
  or more computers on a network (e.g. the
  Internet)
• Protocols allow coordination between programs
  over the Internet
• For example, web browser (Internet Explorer) and
  web server (www.google.com)

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Next Week

• May want to look ahead for lab next week
• Rest of Chapter 1
• Viewing local webpages
• Chapter 2 - HTML
• HTML basics
• Formatting text
• Images, hyperlinks, lists
• Tables

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Questions?