UNDERSTANDING COMPUTERSComputer Applications
Mrs. Stern
Computer History3 Generations of Computers
1. The Vacuum Tube Years2. The Era of the Transistor3. Transistors on a Chip
The Vacuum Tube Years (1946-1958)
Computers were: Huge Slow Expensive Often undependable
ENIAC was built in 1946 18,000 vacuum tubes Took up a lot of space Gave off a lot of heat
Cooled down by a gigantic air conditioner & still overheated regularly
ENIAC Electronic Numerical Integrator and Calculator
The Era of the Transistor (1959-1964)
Transistor was like the vacuum tube only better:
Faster More reliable Much smaller Cheaper to build Gave off virtually no heat 1 transistor replaced 40 vacuum tubes
What it looked like
Transistor Radio
1964 Transistor Beads
Stem
Transistors on a Chip (1965-current)
With the invention of Integrated Circuits or Microchip, thousands of transistors fit into one microchip
The number of transistors that fit onto a chip doubled every two years
Today: Millions per microchip
Computers today can: Carry out instructions in billionths of a
second Are sometimes the size of a watch
Since electricity travels 1 foot in a billionth second
The smaller the distance the faster the speed
What are computers made of?
A combination of:Hardware
& Software
What is Hardware? Hardware – the tangible, physical
equipment that can be seen and touched Keyboard Monitor Printer Computer chips
What is software? Software – the intangible instructions
that tell the computer what to do PowerPoint Windows XP Sims City Oregon Trail
Programmers – write the instructions that tell the computer what to do
Computers are Simple Devices They perform FOUR basic functions:
1. Store data and programs2. Function unattended due to its ability to
interpret and follow instructions it is provided 3. Do arithmetic calculations4. Perform logical comparisons
What makes it such a powerful device?
It only has FOUR basic functions Its tremendous speed Its accuracy Its ability to store vast volumes of data
Where are the instructions stored?
In the computers memory:1. Internal memory (ex. microchips)
RAM (random-access memory) This is temporary & can be erased. (ie: Microsoft Office Xp, Internet Explorer)
ROM (read-only memory) - This is permanent & can not be changed or erased.
2. External memory (ex. DVD’s & hard drives)
Input & Output DevicesInput device: hardware that permits the
computer to accept data o Keyboard o A mouseo Bar-code scannero Light peno Touch display screeno Speech recognition device
Output DevicesHardware which reports the information in a form we can
understandmonitor printerrobots sound or music speakers
Processors Is the computer chip that receives &
carries out the instructions from the software
All computers big & small have processors also known as Central Processing Units or CPUs
Referred to as brains of the computer
Functions the processor performs:
Receives & temporarily stores instructions & data to be processed
Moves & changes stored data Arithmetic calculations Makes decisions of logic (ex: determines
if two numbers are equal)
External Storage
They hold data outside the memory of the computer.
They connect to the computer & are under the control of the processor at all times
Most common: USB Flash Drive External hard drives CD/DVD
Computer MemoryMemory is measured in bytes
8 bits = 1 byte1000 bytes = 1 kilobyte (KB)1000 kilobytes = 1 megabyte (MB)1000 megabytes = 1 gigabyte (GB)1000 gigabytes = 1 terabyte (TB)
You should NOWunderstand computers