Presentation on theme: "LIS508 lecture 3: computer & input devices Thomas Krichel 2002-10-06."— Presentation transcript:
LIS508 lecture 3: computer & input devices Thomas Krichel
Admin news Grades for the quizzes will be made available at 3a/grades/secret.htmlhttp://wotan.liu.edu/home/krichel/lis508w0 3a/grades/secret.html where secret is your word, transliterated into all lowercase, example –seCret secret –SecrEt secret
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
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.
structure general things about computers looking at computer hardware bus input devices –keyboard –mouse –other
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.
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
Basic parts of a PC Display do not open Inputno need to open –Keyboard –Mouse etc System Unitmay be opened –Logic system –Display system –Storage system –Input output system –Communication system
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
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
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)
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
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
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
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.
The components on the bus The display system –Video card Storage system –Hard disk –Floppy disk –CD-rom –CD-R –CD-RW
Other components on the bus Modems, allow communication over a phone line –Internal modems with own serial device –It squeaks Network interfaces –network cards
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
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
Keys on a keyboard Typewriter keys Function keys Arrow keys Editing keys Numeric keypad Alt and Control keys Escape, windows key Obsolete keys
Scholes layout Initial layout be Christopher Scholes around 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.
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.
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!
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
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
other devices Replacements for a mouse are –trackballs –touchpads –joysticks Pen-based devices –vary with respect to text recognition
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
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
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