LIS508 lecture 3: computer

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LIS508 lecture 3 computer input devices

• Thomas Krichel
• 2002-10-06

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Admin news

• Grades for the quizzes will be made available at
  
• http//wotan.liu.edu/home/krichel/lis508w03a/grade
  s/secret.html
• where secret is your word, transliterated into
  all lowercase, example
• seCret ? secret
• SecrEt ? secret

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Literature

• Peter Norton New inside the PC chapter 1 and 5
• Ruth Maran and Paul Whitehead Teach yourself
  computers visually, chapter 1 and 3
• Hutchinson and Sawyer chapter 2
• White, part 5

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Hardware and Software

• Hardware is anything in the computer you can
  touch.
• Software are the instructions that make the
  computer do things.
• In early days, software was closely tied to
  hardware. It could only run on machines of a
  specific hardware and was useless on other
  machines.

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structure

• general things about computers
• looking at computer hardware
• bus
• input devices
• keyboard
• mouse
• other

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Computers

• An old distinction is the following
• A Mainframe is a computer that are used by many
  people in an organization. They access it through
  terminals.
• A personal computer is a machine that is used by
  only one person at a time. In olden days it could
  only do one thing at a time.
• A PC is a special type of personal computer.

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What is a PC

• The PC was first brought out by IBM in 1981
• IBM published the design.
• Processor chips supplied by Intel.
• Software to run it was bought from Microsoft
• Microsoft had the right to have other companies
  use the operating system.
• A PC is any computer that basically follows this
  tradition.
• Intel processor
• Microsoft software

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Basic parts of a PC

• Display do not open
• Input no need to open
• Keyboard
• Mouse etc
• System Unit may be opened
• Logic system
• Display system
• Storage system
• Input output system
• Communication system

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Opening the system unit

• Voltages used in the PC are 3 to 12 V
• Be aware of static electricity, touch first
  unpainted part of case first
• Keep power cable plugged in a grounded socket
• Never open sealed part of the power supply

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Logic system I

• Motherboard
• green plastic sheet
• with traces and slots
• usually complying to a standard called plug and
  play
• Jumpers can set key features
• Jumper wires stick out of the motherboard
• Can be shortened with jumpers
• Do not change unless you have to

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The logic system II

• CMOS or flash memory
• Powered by battery
• holds the Basic Input Output System (BIOS)
• Central Processing Unit (CPU), recognizable
  through its fan
• Cache memory for CPU
• Main memory socket
• The Bus (see later)

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BIOS

• Is the software that makes the components of the
  PC work together
• When the computer boots it tells you how to
  enter setup
• There you can make changes to the BIOS setting
• The way that you do this is not standardized
• It usually is a simple menu.
• Be careful

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Usual things to set in the BIOS

• Set the hardware clock
• Set processor speed setting
• Tell the machine what disks you have
• Power management options
• Automatic wake up
• Boot sequence setting

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The Bus

• Set of connections between devices in the system
  unit. Not very precisely defined
• Types of bus
• Industry Standard Architecture ISA bus (16 bit),
  old
• Peripheral Component Interconnect PCI bus (32
  bit)
• Accelerated graphics port (AGP) bus, only for
  graphics

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The CPU

• Quality of CPU is a major component of the speed
  of the machine
• Speed of the CPU is measured in Hertz, as the
  number of instructions per second.
• Intel are the main manufacturer
• Pentium
• Celeron Processor
• but other manufacturers may be offering better
  quality/price.

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The components on the bus

• The display system
• Video card
• Storage system
• Hard disk
• Floppy disk
• CD-rom
• CD-R
• CD-RW

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Other components on the bus

• Modems, allow communication over a phone line
• Internal modems with own serial device
• It squeaks
• Network interfaces
• network cards

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Input/Output components

• Parallel port
• Parallel because it can move a whole byte at a
  time
• Mainly used for connection to a printer
• Nowadays it can handle bidirectional traffic
• Serial port
• One bit at a time -- Uses thin cable
• Slow -- inexpensive
• Universal serial bus (USB) replaces those

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Universal Serial Bus (USB)

• It is a new, rectangular port device
• 4 wires
• 2 for power
• 2 for communication
• USB has a hub/slave technology
• One USB line can connect to a hub
• The hub has several outgoing lines, that connect
  to other devices
• This is achieved by a complex set of software

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Keys on a keyboard

• Typewriter keys
• Function keys
• Arrow keys
• Editing keys
• Numeric keypad
• Alt and Control keys
• Escape, windows key
• Obsolete keys

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Scholes layout

• Initial layout be Christopher Scholes around
  1860.
• Early typewriters jammed when adjacent keys were
  typed to fast.
• Scholes design resulted from trying to avoid this
  occurrence.
• This resulted in the famous qwerty keyboard.

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Dvorak keyboard

• An efficient keyboard for the English language,
  patented by August Dvorak, cousin of the
  composer.
• Result of efforts to study typewriting behavior.
• Studies in the US Navy suggest that the payback
  period would be 10 days from learning Dvorak.
• From my own experience, doubtful.

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The mouse

• There are two-button and three button mice.
• Since MS uses two buttons, three button mice are
  a dying species.
• The third (middle) button can be emulated on
  two-button mice by pressing the left and the
  right button at the same time.
• Use of the mouse is best avoided!

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The two buttons

• Primary button -- usually left
• Secondary button usually right
• Actions in Microsoft windows
• Left click
• Right click
• Left double click (time adjustable)
• Left drag and drop
• Right drag and drop

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Health risks

• Keyboard and mouse usage can cause serious
  injury.
• From my experience, they are often not be the
  lone cause.
• Others are
• Stress
• Bad posture

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other devices

• Replacements for a mouse are
• trackballs
• touchpads
• joysticks
• Pen-based devices
• vary with respect to text recognition

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text and code scanners

• bar-code readers
• magnetic ink character recognition such as on
  bank checks.
• optical mark recognition
• optical character recognition
• more general form of reading characters out of
  handwriting or print
• expensive and error-prone

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image scanners

• most widely used digitization device
• you can try to run OCR once you have the image
• resolution measured in dots per inch. dpi
• more dpi crisper image
• fewer dpi smaller file

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audio input

• Microphone with speech recognition software
• This used to be mainly for those who can not
  type
• But the quality has improved, and maybe we will
  use it for more general input.
• Other analog to digital sound converters
• sound cards
• MIDI board

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Other devices

• sensors
• biometric devices

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• Thank you for your attention!