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COSC1078 Introduction to Information Technology Lecture 10 Binary Representation

James Harland james.harland@rmit.edu.au. COSC1078 Introduction to Information Technology Lecture 10 Binary Representation. Introduction. Who is this bloke?. Introduction. Overview. Questions? WebLearn Test 1 Assignment 1 Binary Representation Questions?. Introduction to IT.

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COSC1078 Introduction to Information Technology Lecture 10 Binary Representation

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  1. Intro to IT James Harland james.harland@rmit.edu.au COSC1078 Introduction to Information TechnologyLecture 10Binary Representation

  2. Intro to IT Introduction Who is this bloke?

  3. Intro to IT Introduction

  4. Intro to IT Overview • Questions? • WebLearn Test 1 • Assignment 1 • Binary Representation • Questions?

  5. Intro to IT Introduction to IT 1 Introduction 2Images 3Audio 4Video WebLearnTest 1 5Binary RepresentationAssignment 1 6 Data Storage 7Machine Processing 8 Operating Systems WebLearn Test 1 9 Processes Assignment 2 10 Internet 11Internet Security WebLearn Test 3 12Future of IT Assignment 3, Peer and Self Assessment

  6. Questions? How did you spend 6-8 hours on this course last week? This week? Lecture 10: Binary Representation SE Fundamentals

  7. Intro to IT Assessment Process • Submit all assignments via Blackboard in the Learning Hub • Assignment 1 due 11.59pm Sunday 1st April • Assignment 2 due 11.59pm Sunday 6th May • Assignment 3 due 11.59pm Sunday 27th May • Late assignments attract a penalty of 10% per day late, up to a maximum of 50%

  8. Intro to IT Assignment • Assignment will be in three parts • Overall task is to produce a video • Groups of up to 3 • Assessed by final video and group blog • Part 1: images and audio (end of week 5) • Part2: hardware (end of week 9) • Part 3: reflection, research (end of week 12)

  9. Intro to IT Assignment 1 • Use GIMP (or a similar tool) to perform some manipulations on an image • Use Audacity to perform some manipulations on sound • Use a movie making tool to produce something like (and much better than!) ‘Lord of the Controllers 1 & 2’ • Email me your group and its name so that I can set up a blog on the Learning Hub

  10. Overview 01010100001010101010100110100010101001101001010010100011100010101010100101111001001010… Lecture 10: Binary Representation Intro to IT

  11. Intro to IT History • … • Babbage’s Difference Engine (1849) • Babbage’s Analytical Engine (1837-1871, never built) • Turing’s Universal Machine (1936, mathematical model) • Turing digital Boolean-logic multiplier (1937) • Colossus (1943, destroyed 1945) • ENIAC (1946) • Von Neumann architecture (c. 1945) • EDVAC (1949) • CSIRAC (1949)

  12. Computer Memory Cells of 8 bits each (one byte) … … Most significant bit Least significant bit address Lecture 10: Binary Representation Intro to IT

  13. Random Access Memory (RAM) • Random access means any cell can be accessed at any time (and in any order) • Volatile – contents cleared when machine is switched off • Very fast compared to other forms of memory • DRAM: dynamic RAM (replenishes charges constantly) • SDRAM: synchronous DRAM – faster still • Often have small very fast caches and registers Lecture 10: Binary Representation Intro to IT

  14. Magnetic Disk • Thin spinning metal disk with magnetic coating • Each disk contains a number of circular tracks • Often several disks stacked on top of each other • Cylinders made up of tracksmade up of sectors • Can have very large storage this way • Slow access time! Lecture 9: Data Storage Devices Intro to IT

  15. Magnetic Disk (Hard Disk) Seek time: move heads from one track to another Latency time: half time for complete disk rotation Access time: seek time + latency time Transfer rate: rate data can be read from disk `Typical’ Hard disk Seek time: 2ms to 15ms Latency time: 8ms to 20ms Transfer rate: 0.5 GB per second Sounds fast, but is actually quite slow … Lecture 9: Data Storage Devices Intro to IT

  16. Optical Disks (CDs, DVDs) Laser readers rather than magnetic ones Disks more error-tolerant than magnetic ones Lecture 9: Data Storage Devices Intro to IT

  17. Flash Drives • Disks of all sorts are slow compared to other circuits • Flash drives ‘write’ small electronic circuits • Eventually decay after many changes of data • Suitable for slow-changing data, not main memory • Portable and much more resilient than disks Lecture 9: Data Storage Devices Intro to IT

  18. Older Storage Types Magnetic tape `Floppy’ disk (5.25’’ disk) 3.5’’ disk Lecture 9: Data Storage Devices Intro to IT

  19. Binary Codes “Meet me at Fred’s” 234 12.43434343 -620 0 1 1 0 0 1 1 0 Lecture 10: Binary Representation Intro to IT

  20. ASCII • American Standard Code for Information Interchange • 7-bit patterns to represent • letters (upper and lower case) • numbers • , . , ; “ $ % @ * & ! ? < > … • Total of 128 different characters Lecture 10: Binary Representation Intro to IT

  21. ASCII 01001000 H 01100101 e 01101100 l 01101100 l 01101111 o 00101110 . Hello! Unicode: uses 16 bits, can do Chinese, Japanese & Hebrew characters Lecture 10: Binary Representation Intro to IT

  22. Numbers Represented in binary notation 25 in ASCII is 00110010 00110101 8 bits per digit seems too much! Can represent 256 different numbers in 8 bits … Don’t want to add, multiply etc. in ASCII … Remember that 1 + 1 = 10 … Lecture 10: Binary Representation Intro to IT

  23. Two’s Complement How do you store negative numbers? Lecture 10: Binary Representation Intro to IT

  24. Two’s Complement 0 first means +ve (sign bit) 1 first means –ve +ve: Count from 0 up to 01n-1 -ve: Start from 1n down to 10n-1 3 is 011, -3 is 101 2 is 010, -2 is 110 1 is 001, -1 is 111 Lecture 10: Binary Representation Intro to IT

  25. Two’s Complement 1 + 2: add in obvious way 3 – 1: calculate as 3 + (-1) 011 + 111 = 1010 Answer is 010, ie 2. Can add and subtract with the same circuits Lecture 10: Binary Representation Intro to IT

  26. Excess Notation A different encoding of the numbers “naive” bit pattern encodes 4 more than actual value 100 (looks like 4) encodes 0 101 (looks like 5) encodes 1 110 (looks like 6) encodes 2 Lecture 10: Binary Representation Intro to IT

  27. Floating Point exponent Mantissa sign bit 1 bit for sign 3 bits for exponent 4 bits for mantissa 100.101 Lecture 10: Binary Representation Intro to IT

  28. Floating Point • Mantissa: digit sequence (1st digit always 1) • Exponent: where to put the . • This is generally given in ‘excess’ notation • Binary form of 2.423 x 104 01011001 means +ve 0.1001 shifted 101 place = 1.001 Lecture 10: Binary Representation Intro to IT

  29. Truncation Errors Beware adding small numbers to large ones! Finite length of encoding means that sometimes digits are lost Not often a problem, but can be … Lecture 10: Binary Representation Intro to IT

  30. Parity Bits • Add a ‘parity bit’ to each byte • Odd parity: make total of 1s in all 9 bits odd • Even parity: make total of 1s in all 9 bits even • If parity is wrong, then an error has occurred Lecture 10: Binary Representation Intro to IT

  31. Intro to IT Conclusion • Get Assignment and WebTest done this week • Do online quizzes later this week • Keep reading! (book particularly)

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