Understanding Computers

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

Binary System BrainPop - Binary

http://www.brainpop.com/

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