Week 2 Day 1

Information technology:
  collection of tools to support manipulation of information.
 - computers (a)
 - TV/radio? (b)
 - books?    (c)

All three manipulate information. However, we generally think about
(a) when talking about IT.

Computers can be:
- Monolithic
iMac or laptop has all devices bundled together
Simple and convenient
Power switch on chassis or keyboard
- Component	
Desktop PC's with separate components
Monitor
Hard Drive
Speakers
Etc.
Allows user to mix and match
Power switch on box with disk drives


Interactive video screen
Bit-mapped 
Display information stored in computer memory
CRT's (cathode ray tube) and LCD (liquid crystal display)
Screen displays images from its memory
Virtual Reality


Cables connect components to computer and to power source
Cables need to be plugged in correctly
Sockets and plugs labeled with icons


RGB
Primary colors of light
red, green, blue
Colors on screen created by combining different amounts of primary
colors


Grid of small units called pixels (for picture elements)
Size of the dot on letter i
Computer draws each pixel in the designated color for the image or figure
The more pixels in each row and column, the smoother and crisper the image (high resolution)


Buttons:
Color the screen's pixels to make a believable looking button
and to give the ilusion of movement when "clicking" the mouse on top.

Moving the mouse pointer
Mouse pointer is drawn on screen like any image
When mouse moves, computer re-draws in correct direction 
Fast refresh rate (30 times per second) creates illusion of motion
Computer keeps track of which pixel is at the point of the arrow

Computer keeps a list of every button drawn on screen
When mouse is clicked, computer redraws the button under mouse,
software reacts by performing appropriate action 


Motherboard
Printed circuit board inside processor box
Contains most of the circuitry of PC system
Smaller circuit boards, called daughter boards or cards, plug into
motherboard for added functionality 
Motherboard contains the microprocessor chip and the memory


Microprocessor (more correctly "processor")
"Smart" part of system
Performs actual computing


Memory:
Where program and data are located while program runs
RAM: Random Access Memory
PC Contains millions of bytes of RAM
What Random Access means
Any item can be retrieved directly
Unlike sequential access 


Hard disk:
High-Capacity, persistent peripheral storage device
Stores programs and data not in immediate use by computer
Made from magnetized iron compound
Information remains whether PC is on or off
Called permanent or persistent storage

Ram memory is volatile
Information is lost when power turns off
If computer fails or power-cycles, only data on disk will survive


Hardware is old term for metal items used in construction
Refers to physical parts of computer
Functions implemented directly with wires and transistors
Software is a term created for computers
Means programs or instructions the computer follows to implement functions


Algorithm
Precise and systematic method for solving a problem
Examples:
Arithmetic operations
Sending a greeting card
Searching for a phone number
Determining when a mouse pointer hovers over a button
Algorithms need to be precise


Writing out steps of algorithm is called programming
Program is an algorithm written in specific language for specific set of conditions
Running a Program
 Click on program icon (ex. Word)
We instruct computer to run or execute the program.


Booting: Start computer
Rebooting: Re-start computer
Boot instructions are stored in a microchip called the boot ROM
Term comes from "bootstrapping"


HOMEWORK

p. 24: 1,3,4,6
p. 26: 1,3