1. Using Computers
CS French
Chapter 1

2. Name some typical tasks a computer is used for.
Editing documents
Calculations
Drawing
Storing data
Controlling machines

3. What have these tasks got in common?
Information
simplicity
repetition
speed
accuracy
A computer is good at doing simple and repetitive tasks quickly and accurately. It deals primarily with information.

4. Some definitions and terms.
Computer - information processor
Personal computer (micro-computer) - dedicated to one person
Peripherals - devices ‘external’ to a computer and connected to it.
Hardware - all equipment, computer and peripherals
Computer program - a set of instructions written in a form that the computer can understand. (eg Microsoft Word)
Data - numbers and text. (eg. A drawing)
Software - programs and data.
Information - data processed into a useful form.
Executing (running) a program - the instructions being carried out by the computer.

5. Characteristics of a Computer
Think about what it is that makes a computer different from other machines.
ability to perform high speed calculations.
ability to take in and store information for future use.
ability to take in and store a sequence of instructions.
ability to obey a sequence of instructions.
ability to use simple logical rules to make decisions for their own internal control.

6. Elements of a Computer System
Peripheral
Devices
Keyboard
Screen
Mouse
Printer
Plotter
Modem
Floppy disk drive
Hard disk
Compact disk
Magnetic tape
Network ‘card’
Scanner
Computer
CPU
Processor
Input/
Output
unit
Memory
(RAM)
Control
Unit
ALU
data bus
Exercise: Classify the listed ‘peripherals’ as input, output, auxialliary storage or communication devices!

7. Information Storage and Retrieval
Memory (Main Storage)
often known as Random Access Memory (RAM)
part of the Central Processing Unit (CPU) - inside computer
usually volatile - loses its contents when power is turned off
holds data and programs currently in use.
very fast access to contents.
electronic components (chips)
relatively expensive
limited capacity
What do you think are the problems of memory?

8. Information Storage and Retrieval
Auxilliary (backing) Storage
peripheral (external ) to CPU
non-volatile - does not require power to keep information.
holds data not currently in use
slower than memory
usually mechanical - disks (hard, CDROM, floppy, zip)and tapes
less expensive per unit of storage
much larger capacity
What are the dis-advantages of auxilliary storage?