What s a Computer Analog Digital does it matter Technically there are two categories of computers analog or digital Designs reflect two different ways to look at or analyze the world Copyright 2008 by Helene G Kershner What s a Computer Analog Digital does it matter Analog device operates with measurements that are continuous such a voltage temperature and rotation Speedometer in your car Traditional thermometer Classic clock An Analog computer uses analog measurements in it s calculations Analog measurements are physical phenomena such as electrical mechanical or hydraulic quantities to model the problem being solved http en wikipedia org wiki Analog computer Very fast Somewhat inaccurate Difficult to replicate results can you spin a wheel at exactly the same rate twice in a row Copyright 2008 by Helene G Kershner What s a Computer Analog Digital does it matter This device is a Harmonium It is a mechanical analog computer designed analyze sine waves used in Fournier Analysis What s a Computer Analog Digital does it matter Digital Computer Information is represented by counting This is what we think of as a computer All information used by the machine is in one of two states ON 1 or Off 0 Things we can count include Change from a dollar Number of students registered in CSE 111 Tuition in dollars Highly flexible Easy to replicate Copyright 2008 by Helene G Kershner What s a Computer Analog Digital does it matter Moving from Analog to Digital Digital Age Clock Hands moving in a circle digits on a screen Telephone 10 digits in a circle distance from beginning was used to represent the digit push a button Voice as a sound wave voice as a pattern of pulses Television and Movies Pictures as a series of light waves pictures as a pattern of dots pixels It is all about speed and ability to replicate results Copyright 2008 by Helene G Kershner What s a Computer The Binary Machine Computers speak a very simple language Two digits 0 and 1 Don t really understand the data or instructions they are given Know how to follow them circuit path The 1 state current is present ON The 0 state current is absent OFF Binary The entire language of mathematics can be converted into a system that just uses 0s and 1s Copyright 2008 by Helene G Kershner What s a Computer The Binary Machine Computers use Binary 0 1 Base 2 People do not we use Decimal 0 1 2 3 4 5 6 7 8 9 Base 10 Perhaps this is because we have 10 finger and 10 toes Modern computers take in decimal number and letters Translate them into 0s and 1s Do whatever they do Magic Give us the results in a way human understand Copyright 2008 by Helene G Kershner What s a Computer The Binary Machine In decimal every number is represented as the digits 09 In binary every number is represented as the digits 0 1 Decimal to Binary conversion Decimal Binary 0 1 2 3 4 5 6 7 8 9 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 Copyright 2008 by Helene G Kershner What s a Computer The Binary Machine For people in the know 0 0000 1 0001 2 0010 http www thinkgeek com tshirts frustrations 5aa9 zoom Copyright 2008 by Helene G Kershner What s a Computer The Binary Machine BIT for Binary Digit each 0 or 1 in the binary system Single bit is not overly useful BYTE a group of bits usually 8 Each byte represents one character of data Numbers letters special characters etc Letter numbers and symbols are the form we use to represent information WORD the number of bits that can be processed at one time by the central processing unit the brain of the computer Early computers Apple II 8 bit Words Modern machines can process up to 64 bits word Copyright 2008 by Helene G Kershner What s a Computer The Binary Machine Computers are described by amount of processing memory they contain Usually described in terms of bytes K 1000 bytes Megabyte or megs MB 1000K or 1 million bytes Gigabyte or gigs GB 1000MB or 1 billion bytes Terabyte 1000GB or 1 trillion bytes The notation has gained common usage Earn 100K House is priced at 450K Copyright 2008 by Helene G Kershner What s a computer For many a computer is a black box Incredible machine that works mysteriously How is of little consequence Magic Copyright 2008 by Helene G Kershner What s a computer Basic parts Input Output Input Central Processing Unit Brains Memory Output Input Output computer howstuffworks com cd htm staples com dell com Copyright 2008 by Helene G Kershner What s a computer Basic parts Every computer is made up of the following components A Central Processing Unit Arithmetic Logic Unit Control Unit Memory Primary Memory Usually called RAM Secondary Memory or Mass Storage Disk drives Input and Output Devices Copyright 2008 by Helene G Kershner What s a computer Processing Unit Brains of the Machine Central Processing Unit Arithmetic and Logic Unit ALU Control Unit Associated Primary Memory Working together these are the core or any computer Size doesn t matter Copyright 2008 by Helene G Kershner What s a computer Central Processing Unit Arithmetic Logic Unit As the name implies performs two functions Arithmetic Responsible for performing the arithmetic operations of addition subtraction multiplication and division Logic Makes simple decisions by comparing alternatives and choosing between them Less than greater than equal to AND OR and NOT Copyright 2008 by Helene G Kershner What s a computer Control Unit The arithmetic and logic unit is responsible for mathematical calculations and comparisons The Control Unit is the computer s internal coordinator Traffic Cop Sends out electronic signals directing the computer to perform specific tasks such as Move data between memory and the CPU Activating the ALU Receiving data Sending information to an output device The control unit manages the flow of data throughout the machine based on the instructions it receives from programs Copyright 2008 by Helene G Kershner Using Binary Coding Information Remember Bit 0 or 1 Binary Digit Byte the number of bits used to represent letters numbers and special characters such as Word number of bytes a computer can process at one time by the CPU So Bits form Bytes and Bytes form Words Copyright 2008 by Helene G Kershner Using Binary Coding Information Two common formats for coding letters numbers and special characters are ASCII American Standard Code for Information Interchange 7 bit code Originally used on non IBM systems Basis of most currently used systems EBCDIC Extended Binary Coded Decimal Interchange Code 8 bit code Originally used