Input

Receives (accepts) information (data) and makes it available to the computer. The "I" of I/O (Input / Output).

Some examples of Input Devices are:

· 
Computer Terminal is made up of a keyboard and a monitor. Image from www.rcubed.com

Graphics Tablet or Graphics Pad
Image from www.wikipedia.org

Processing (CPU)

PROCESSING - happens in the central processing unit (CPU). This where the computer does its work, where the processing takes place. The CPU contains the : control unit and arithmetic logic unit. *The integrated circuit chip or the microprocessor is here. It does the 4 jobs of the computer. 

Two parts to processing: CONTROL UNIT and ARITHMETIC LOGIC UNIT

·  1. Control Unit- sends the data to the memory unit or to the arithmetic unit .  It may be compared to a "Traffic cop" controlling the flow of information.

·  2. Arithmetic Logic Unit (ALU) - calculates or compares the data, performs calculations and functions; this is the unit that does the processing.

Speed Time : microsecond = one millionth of a second

·  nanosecond = one billionth of a second

·  picosecond = one trillionth of a second
Microprocessor Image by Richard Wheeler, 09/20/07

*It takes approximately two seconds for the average person to add two three digit numbers.  In two seconds, the computer of today can do calculations that would take a person over four or five years to do by hand.

Memory / Storage

MEMORY - this is where data is stored until it is needed

TWO KINDS OF MEMORY: RAM and ROM 

·  1. Random Access Memory (RAM) - temporary memory or volatile storage known as primary storage, stores the programs that you write, it is changeable memory, when the computer is turned off, RAM is lost 

·  2. Read Only Memory (ROM) - permanent memory, stores the programs that are built into the computer (like the operating system), this memory can not be changed 

Memory measured in kilobytes: 

·  kilobyte (K) 2¹⁰ or 1024 bytes 

·  megabyte (Mb) 2²⁰ or 1 million bytes 

·  gigabyte (Gb) 2³⁰ or 1 billion bytes (1 gigabyte would be 1 pickup truck full of printed paper)

·  terabyte (Tb) 2⁴⁰ or 1 trillion bytes  (10 terabytes would be approximately the printed Library of Congress)

·  petabyte (Pb) 2⁵⁰ or 1 quadrillion bytes (200 petabytes would be ALL printed material, or 500 million floppy disk of informaton)

·  Exabyte (Eb) 2⁶⁰ or (1,000,000,000,000,000,000 bytes)  (According to Berkeley study in 1999 all human produce information might possibly total 12 exabytes)

• Zettabyte (Zb) 2⁷⁰ or (1,000,000,000,000,000,000,000 bytes) (Possibly by 2010 there may be almost 1 zettabyte of informaton on the internet world wide.)
• Yottabyte (Yb) 2⁸⁰ or (1,000,000,000,000,000,000,000,000 bytes) (it would take 86 trillion years to download 1 yottabyte file at our present download speeds!)

• Brontobyte (Bb) 2⁹⁰ or (1,000,000,000,000,000,000,000,000,000 bytes) (This would be able to record everything)

Memory/Storage Continued

You may output to a storage device which is considered secondary storage

Examples of Storage Devices
(Secondary Storage) include:

Output

OUTPUT DEVICES - device that gives the data back from the computer in a useable form. The "O" of I/O (Input / Output). The types of output are softcopy, hardcopy (also called a printout)

Examples of devices that produce Softcopy are:

• CRT(Cathode Ray Tube) or LCD (Liquid Crystal Display)  monitor
• modem 
• robot 
• speech synthesizer

More examples of output devices

• hard disk
• Optical Disks (Also CD-R and CD-RW are compact disk "burners")
• Floppy Disk/Super Disks
• reel to reel tape drive
• Digital Audio Tape

Below is a Reel to Reel Tape and Tape Drive (Image from Creative Commons Attribution ShareAlike 2.5)

Output Continued

Examples of devices that produce Hardcopy (printout) are:

·  PLOTTER  - may print blueprints, maps, etc. (image below is courtesy of Wikipedia Commons 09/20/07)

·  PRINTER - prints the information onto paper 

 Kinds of printers prevalent today: