Larry Zhang. Office: DH

Transcription

1 CSC258 Week 1 1

2 Larry Zhang Office: DH

3 Today s outline Why CSC258 What is in CSC258 How to do well in CSC258 Start learning 3

4 Why takecsc258? 4

5 Learning the Magic magic magic CSC258 CSC369 5

6 More specifically How do we express 1 s and 0 s using a piece of silicon? How does the computer do everything with just 1 s and 0 s? What is stored in that fortnite.exe file, what exactly happens when I double-click on it? How does the CPU run an if-statement, or for loop, or recursion? CSC258 has all the answers! 6

7 After learning CSC258 You ll know everything about how a computer is physically built, and you can build one if you want. Base on your hardware knowledge, you will be able to engineer the performance of your software like never before. People who are really serious about software should make their own hardware. -- Alan Kay 7

8 What s incsc258? 8

9 The architecture of a computer hardware, level by level, bottom-up Assembly Language Processors compute stuff Arithmetic Logic Units Finite State Machines remember stuff Devices Flip-flops Circuits Gates Transistors 9

10 We learn the whole real deal From atom level to assembly level Above the assembly level is the Operating System, whose main job is virtualization, i.e., create convenient illusions. Everything you learn from every CS course are all illusions except for CSC258 10

11 How to do well in CSC258 11

12 First of all Be interested 12

13 Course website All course materials are here. 13

14 Marking scheme Labs: 3% x 10 = 30% Midterm: 22% Final exam: 45% Quizzes: 3% 100% 14

15 Labs (starting from Week 2) Hands-on exercises in which you will build real pieces of hardware. Prelabs are done individually, in-lab work is done in pairs. ONLY go to the lab section that you are registered to on ACORN. If you want to switch lab section, find someone who is willing to switch and let Larry know. On the discussion board, use Search Teammates for finding a partner. 15

16 Prelab Reports For most of the labs, you will be required to submit a prelab report (a PDF file) to MarkUs before the labs start. Must be completed individually Submission deadline is typically Tuesday 3pm To get the mark for the prelab report ú ú ú do your work and submit something meaningful don t plagiarize not submitting anything would be much better than plagiarizing 16

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18 Lab software We will use Logisim-Evolution The reference of the software has been posted on the course website. Task for this week: download the software, read the reference, and familiarize yourself with it. Note: I must be Logisim-Evolution downloaded at the link in the reference. Do NOT use the original Logisim or its other variations. 18

19 Weekly Quizzes We will use Quercus for online quizzes Starting in Week 2 Useful practices for tests and exams. Deadline for quizzes is every Sunday 10:00pm. You ll be told whether your answer is correct immediately, and you can try up to three times. We will record your highest score. 19

20 Tests! Midterm out of class March 1, 5:10pm~6:40pm (90 minutes) Let Larry know by Jan 31 if you have a conflict. Final exam Some time in April Must get >= 40% 20

21 Discussion board All course announcements will be posted here. Daily reading is required. 21

22 Office hours Monday 5-6:30 pm Tuesday 5-6:30 pm Office hours are good. 22

23 Student Feedback Give us frequently (e.g., every week) feedbacks on how things are going. It is very useful for improving your learning experience in a timely manner. Anonymous feedback form: ú link on the course website Or, just drop by and have a chat with Larry 2-23

24 Textbook: DDCA Digital Design and Computer Architecture, 2nd edition, 2012by David Harris, Sarah Harris Available online at UofT library (link in course info sheet) 24

25 A typical week of CSC258 Monday/Tuesday: go the lectures. By Tuesday 3pm: submit prelab report. Tuesday/Wednesday/Thursday: labs. Wednesday: Quiz out on Quercus, starting studying for it. Thursday evening: next week s lab handout released, start working on the prelab. Sunday by 10pm: complete the quiz. 25

26 It will be a lot of work, and a lot of fun! 26

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28 In-class pop quizzes. To participate, you ll need: ú be in the lecture ú have access to a browser (on a phone, tablet or a laptop), or the Kahoot app has nothing (directly) to do with your course grade 2-28

29 Let the learning begin 29

30 Basic Logic Gates 30

31 You already know something 31

32 Logic from math course Create an expression that is true iff the variables A and B are true, or C and D are true. G = (A & B) (C & D) 32

33 G = (A & B) (C & D) A B A&B A B A B AND Gate OR Gate A B C G D You just designed your first circuit in CSC258! 33

34 Gates = Boolean logic If we know the logical expression, we already know how to put logic gates together to form a circuit. Just need to know which logic operations are represented by which gate! Let s meet all the gates. 34

35 AND Gates A B Y Truth table A B Y

36 OR Gates A B Y A B Y

37 NOT Gates A Y A Y

38 XOR Gates A B Y A B Y

39 Bill Gates 39

40 NAND Gates A B Y A B Y

41 NOR Gates A B Y A B Y

42 Buffer A Y This is not as silly as you might think now, as we ll see later A Y

43 A B Y AND Gate This is just a symbol... What does it really look like, inside? How does it work, physically? A B What are these? Power: high voltage (5V) + - R Y Resistor Ground: low voltage (0V) 43

44 + - A B Switches R Y When and only when both A are B are switched ON, Y has high voltage. 44

45 A Gates B Y + - R Gate is like a switch, but controlled by the voltage of the input signal, instead of by a finger. Gate A is switched ON when signal A is of high voltage. When and only when both A and B have high voltage, Y has high voltage. High voltage is 1 (True), low voltage is 0 (False). Y is True iff both A and B are True (Y = A & B). 45

46 A Gate is switched ON when signal A is of high voltage Why? How? What does the inside of a gate look like? Answer: There are transistors. 46

47 Transistors 47

48 One of the greatest inventions of the 20 th century Invented by William Shockley, John Bardeen and Walter Brattain in 1947, replacing previous vacuumtube technology. ú Nobel Prize for Physics in Building block for the hardware of all your computers and electronic devices. 48

49 What do transistors do? Transistors connect Point A to Point B, based on the value at Point C. ú If the value at Point C is high, A and B are connected. C = 1 A B A B ú And if the value at Point C is low, A and B are not. C = 0 A B A B ú Need to know a little about electricity now. 49

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51 Outline of the story Electricity, basic concepts Insulators, conductors, in between, Semiconductors Impure semiconductors, p-type / n-type Put p-type and n-type together -- pn-junction Apply voltage to a pn-junction principle of transistors A real-world manufacturing of transistor -- MOSFET 51

52 Electricity Basics 52

53 Everything is made out of atoms Protons are big (hardly move) and positively charged. Electrons are small (easily move) and negatively changed. Neutrons are big and of course, neutral. Overall, an atom is neutral. 53

54 What is Electricity? Electricity is the flow of charged particles (usually electrons) through a material. 54

55 How do electrons flow? They flow 55

56 How do electrons flow? Electrons want to flow from regions of high electrical potential (many electrons) to regions of low electrical potential (fewer electrons). ú Like water flows from high to low. This potential is referred to as voltage (V). The rate of this flow is called the current (I). Resistance (I = V / R) is like how narrow the water pipe is. 56

57 Note The direction of the current is opposite to the direction of the electron movement, because electrons are negatively charged. 57

58 More on Resistance Electrical resistance indicates how well a materialallows electricity to flow through it: ú High resistance (aka insulators) don t conduct electricity at all. ú Low resistance (aka conductors) conduct electricity well, and are generally used for wires. Semiconductors are somewhere in between conductors and insulators, which makes it interesting 58

59 Outline of the story Electricity, basic concepts Insulators, conductors, in between, Semiconductors Impure semiconductors, p-type / n-type Put p-type and n-type together -- pnjunction Apply voltage to a pn-junction principle of transistors A real-world manufacturing of transistor -- MOSFET 59

60 Semiconductors 60

61 Here comes the chemistry 61

62 silicon Germanium 62

63 Conductivity of Semiconductors Semiconductor materials (e.g., silicon and germanium) straddle the boundary between conductors and insulators, behaving like one or the other, depending on factors like temperature and impurities in the material. 63

64 Impurity 64

65 Pure semiconductor is pretty stable Each atom has 4 valence electrons, forming bonds with other atoms, and the structure is pretty stable. At room temperature, very close to insulator. 65

66 Encourage semiconductor s conductivity N-type: Add some atoms with 5 valence electrons, such as Phosphorus. An extra electron! P-type: Add some atoms with 3 valence electrons, such as Boron. A missing electron, a.k.a., a hole, like a positive electron! 66

67 Encourage semiconductor s conductivity The extra electrons and the holes are charge carriers, which can move freely through the materials. Thus the conductivity is encouraged. This process of adding stuff is called doping, (n or p type). 67

68 Free electrons move like Free holes move like 68

69 Outline of the story Electricity, basic concepts Insulators, conductors, in between, Semiconductors Impure semiconductors, p-type / n-type Put p-type and n-type together -- pnjunction Apply voltage to a pn-junction principle of transistors A real-world manufacturing of transistor -- MOSFET 69

70 PN-junctions 70

71 Bringing p and n together What happens if you brought some p-type material into contact with some n-type material? P - P P P P - n-type - B - B B - B - - B p-type The electrons at the surface of the n-type material are drawn to the holes in the p-type. 71

72 p-n Junctions When left alone, the electrons from the n section of the junction will fill the holes of the p section, cancelling each other and create a section with no free carriers called the depletion layer. Once this depletion layer is wide enough, the doping atoms that remain will create an electric field in that region. 72

73 Because lost electron n-type Electrons initial movement (attracted by holes) P - P P P P - - B - B B - B - - B Because gained electron p-type 73

74 Diffusion increases the width of depletion layer, and drift draws it back. An equilibrium is reached, when the depletion layer is n-type of a certain width. Diffusion Electrons initial movement (attracted by holes) Electric field p-type Electron s movement drawn by the electric field Drift 74

75 Analogy: Spring with weight Diffusion Attracted by gravity (hole) Drift Drawn by spring force field An equilibrium is reached when the spring is stretched by a certain length. 75

76 Summary of pn-junction P N When we put p and n together, they will form a depletion layer with electric field in it. The depletion layer grows up to a certain width, until equilibrium is reached. 76

77 Outline of the story Electricity, basic concepts Insulators, conductors, in between, Semiconductors Impure semiconductors, p-type / n-type Put p-type and n-type together -- pnjunction Apply voltage to a pn-junction principle of transistors A real-world manufacturing of transistor -- MOSFET 77

78 Apply voltage to a PN-junction It could be applied in two possible directions Positive voltage to the P side Positive voltage to the N side 78

79 Forward Bias (Positive voltage to P) P Negative charges sucked out of depletion layer N Positive charges sucked out of depletion layer Depletion layer becomes narrower. 79

80 Reverse Bias (Positive voltage to N) P Negative charges injected into depletion layer N Positive charges injected into depletion layer Depletion layer becomes wider. 80

81 Apply forward bias Depletion layer narrower Easier to travel through Better conductivity Like switch connected Apply reverse bias Depletion layer wider Harder to travel through Worse conductivity Like switch disconnected That s how transistors work! 81

82 Outline of the story Electricity, basic concepts Insulators, conductors, in between, Semiconductors Impure semiconductors, p-type / n-type Put p-type and n-type together -- pnjunction Apply voltage to a pn-junction principle of transistors A real-world manufacturing of transistor -- MOSFET 82

83 Creating transistors Transistors use the characteristics of p-n junctions to create more interesting behaviour. Three main types: ú Bipolar Junction Transistors (BJTs) ú Metal Oxide Semiconductor Field Effect Transistor (MOSFET) ú Junction Field Effect Transistor (JFET) The last two are part of the same family, but we ll only look at the MOSFET for now. 83

84 Metal Oxide Semiconductor Field Effect Transistor 84

85 Gate Source Drain 85

86 Conductor, can apply electric charge to it Metal Oxide Insulator N-type P-type Semiconductors, doped Source Gate Drain 86

87 Put a MOSFET into a circuit Gate Source Drain + - or - + Power: high voltage can be applied to source or drain 87

88 Metal Oxide N-type P-type Put it into a circuit Gate Source Drain Two PN-junctions back-to-back, i.e, N-P-N. So, either source or drain has high voltage, one of the PN-junction must be reverse biased (circuit disconnected). 88

89 Metal Oxide N-type P-type But things change if we apply high voltage to Gate Gate Attract negative charges from p-substrate Create n-type channel between source and drain, CIRCUIT CONNECTED The wider the channel, the higher the current 89

90 Two types of MOSFET nmos (what we just describe) N-P-N Gate high, connected Gate low, disconnected pmos (opposite to nmos) P-N-P Gate low, connected Gate high, disconnected 90

91 Outline of the story Electricity, basic concepts Insulators, conductors, in between, Semiconductors Impure semiconductors, p-type / n-type Put p-type and n-type together -- pnjunction Apply voltage to a pn-junction principle of transistors A real-world manufacturing of transistor MOSFET Use transistors build Logic Gates 91

92 Transistors to Logic Gates 92

93 Create gates using a combination of transistors Physical data: ú High input = 5V ú Low input = 0V ú Switching time: ~20 picoseconds ú Switching interval ~10 ns A A Y Y NOT Gate 93

94 Transistors into gates V cc V cc V cc V cc V cc A A B A A B Y B B Y B Y A B A A A B B AND OR XOR 94

95 NAND is the most awesome logic gate It s cheaper to build All other logic functions (AND, OR, ) can be implemented using only NAND, i.e., it is functionally complete. Challenge for home: implement AND, OR, NOT, XOR using only NAND. 95

96 Next week: Circuit creation 96