UNDERSTANDING COMPUTERS Computer Applications Mrs. Stern
Feb 15, 2016
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