Understanding Computer System Architecture with Dr. John Abraham

1. Background for CSCI 6307 Dr. John P. Abraham Professor UTRGV

2. Layers of a Computing System Dr. John P. Abraham, University of Texas Pan American 4

3. How does computer work with so many languages & Disciplines • Software • Hardware • recognizes • switches that are turned off and on • Transistors can act as switches and amplifiers. • One switch that provides two states, Dr. John Abraham, UTRGV

4. Computer Architecture • What is architecture • Describes how hardware is organized and enhanced for speed and efficiency and how it interacts with software. • Sits in the middle of software and hardware • High level, Low level – assembly & machine languages, Hardware, Movement of electrons • Organization Dr. John Abraham, UTRGV

5. Transistor analogy • C Collector. Power supply voltage • B base • E Emitor • By varying levels of current in B, the amount of current flowing into E can be regulated Dr. John Abraham, UTRGV

6. Switches to store data - 2n • 1 – 2 • 2 -4 • 3 -8 • 4 -16 • 5 – 32 • 6 – 64 • 7- 128 • 8 -256 Dr. John Abraham, UTRGV

7. ASCII and Unicode • 8 bits • UTF-16 16 bits • UTF-32 -32 bits Dr. John Abraham, UTRGV

8. Opcode and Operand • Operation • And what is operated on • How many instructions needed to handle programmatic need? Dr. John Abraham, UTRGV

9. Computer System • CPU - memory • Peripherals (input & output)

10. CPU • Control unit • ALU • Registers • Interconnection Dr. John Abraham, UTRGV

11. Operation of a CPU • 1. Figure out where the next instruction is in the memory (instruction address calculation). • 2. Fetch the instruction • 3. Figure out what the fetched code means (decoding the instruction). • 4. If it requires an operand • a. Figure out where the operand is kept (operand address calculation). • b. Fetch the operand Dr. John Abraham, UTRGV

12. continued • c. If there are multipleoperands repeat a and b.5. Execute the instruction (such asadd, subtract, multiply, jump,loop, etc)6. Figure out the location to storethe result (operand addresscalculation)7. store the result, if there aremultiple results repeat 6 and 7.8. Go back to 1 to do the nextinstruction, or End if it is the lastinstruction.

13. Numbers Natural Numbers Zero and any number obtained by repeatedly adding one to it. Examples: 100, 0, 45645, 32 Negative Numbers A value less than 0, with a – sign Examples: -24, -1, -45645, -32 2

14. Numbers Integers A natural number, a negative number, zero Examples: 249, 0, - 45645, - 32 Rational Numbers An integer or the quotient of two integers Examples: -249, -1, 0, 3/7, -2/5 3

15. Natural Numbers Aha! 642 is 600 + 40 + 2 in BASE 10 The baseof a number determines the number of digits and the value of digit positions 5

16. Positional Notation Continuing with our example… 642 in base 10 positional notation is: 6 x 102 = 6 x 100 = 600 + 4 x 101 = 4 x 10 = 40 + 2 x 10º = 2 x 1 = 2 = 642 in base 10 The power indicates the position of the number This number is in base 10 6

17. Binary Decimal is base 10 and has 10 digits: 0,1,2,3,4,5,6,7,8,9 Binary is base 2 and has 2 digits: 0,1 For a number to exist in a given base, it can only contain the digits in that base, which range from 0 up to (but not including) the base. What bases can these numbers be in? 122, 198, 178, G1A4 9

18. Bases Higher than 10 How are digits in bases higher than 10 represented? With distinct symbols for 10 and above. Base 16 has 16 digits: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E, and F 10

19. Converting Octal to Decimal What is the decimal equivalent of the octal number 642? 6 x 82 = 6 x 64 = 384 + 4 x 81 = 4 x 8 = 32 + 2 x 8º = 2 x 1 = 2 = 418 in base 10 11

20. Converting Hexadecimal to Decimal What is the decimal equivalent of the hexadecimal number DEF? D x 162 = 13 x 256 = 3328 + E x 161 = 14 x 16 = 224 + F x 16º = 15 x 1 = 15 = 3567 in base 10 Remember, the digits in base 16 are 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F

21. Converting Binary to Decimal What is the decimal equivalent of the binary number 1101110? 1 x 26 = 1 x 64 = 64 + 1 x 25 = 1 x 32 = 32 + 0 x 24 = 0 x 16 = 0 + 1 x 23 = 1 x 8 = 8 + 1 x 22 = 1 x 4 = 4 + 1 x 21 = 1 x 2 = 2 + 0 x 2º = 0 x 1 = 0 = 110 in base 10 13

22. Arithmetic in Binary Remember that there are only 2 digits in binary, 0 and 1 1 + 1 is 0 with a carry Carry Values 1 1 1 1 1 1 1 0 1 0 1 1 1 +1 0 0 1 0 1 1 1 0 1 0 0 0 1 0 14

23. Subtracting Binary Numbers Remember borrowing? Apply that concept here: 1 2 2 0 2 1 0 1 0 1 1 1 - 1 1 1 0 1 1 0 0 1 1 1 0 0 15

24. Counting in Binary/Octal/Decimal

25. Converting Binary to Octal • Mark groups of three (from right) • Convert each group 10101011 10101011 2 5 3 10101011 is 253 in base 8 17

26. Converting Binary to Hexadecimal • Mark groups of four (from right) • Convert each group 10101011 10101011 A B 10101011 is AB in base 16 18

27. Converting Decimal to Other Bases Algorithm for converting number in base 10 to other bases While (the quotient is not zero) Divide the decimal number by the new base Make the remainder the next digit to the left in the answer Replace the original decimal number with the quotient 19

28. Converting Decimal to Octal What is 1988 (base 10) in base 8? Try it!

29. Converting Decimal to Octal 248 31 3 0 8 1988 8 248 8 31 8 3 16 2424 0 38 08 7 3 32 8 68 0 64 4 Answer is : 3 7 0 4

30. Converting Decimal to Hexadecimal What is 3567 (base 10) in base 16? Try it! 20

31. Converting Decimal to Hexadecimal 222 13 0 16 3567 16 222 16 13 3216 0 36 62 13 3248 47 14 32 15 D E F 21

32. Binary Numbers and Computers Computers have storage units called binary digits or bits Low Voltage = 0 High Voltage = 1 all bits have 0 or 1 22

33. Binary and Computers Byte 8 bits The number of bits in a word determines the word length of the computer, but it is usually a multiple of 8 • 32-bit machines • 64-bit machines etc. 23

34. ELECTRONICSAN INTRODUCTION Dr. John P. Abraham

35. Matter • Atom – Basic building block of elements • Molecules – Same atoms get together • Compounds – Different Atoms combine • Our body is composed of organic and inorganic matter. • Organic • Inorganic

36. Atom –1

37. Atom-2 Each Element has a certain number of electrons and protons. This is what we use to distinguish one element from another. A table called periodic table is derived from this. An atom has a nucleon which contains protons (positively charged) and neutrons (no charge). An atom also has electrons rotating around the nucleus (BOHR MODEL). A newer model is Quantum Theory.

38. Atom-3 • Electrons are generally in same number as protons thus keeping the charge neutral. • Other terms you will hear are quark (up or down), and electron-neutrino. We will not discuss here.

39. Atom –4 • The electrons rotate around the nucleus in orbits. • Each orbit can have a maximum number of electrons. • Suppose one shell can have 8 electrons. If it only has 7, it will bind with another element to complete that shell. But if it only has 1, it will give up this one to another element by combining with it.

40. Atom –5 • This a copper atom. • Do you see just one electron in the outer shell? More abut it later.

41. Electric charge • Known 600 years before Christ. • If an amber rod is rubbed against fur the rod becomes electrically charged. • During the rubbing process some electrons are transferred from the fur to the rod. • We can also accumulate charge in our body. • Electrostatic charge can damage electronic components.

42. Ions • Recall that I said that an atom can either give up or receive electrons. • If an atom gives up electron(s) it becomes a positive ion. • If an atom gains electron(s) it becomes a negative ion.

43. Insulators • Suppose you only rubbed one end of the rod with fur. The electrons are transferred to that end only. • These electrons can’t travel along the rod because amber, glass, wood etc. are insulators. • Insulators are non-metallic substances such as rubber, glass plastic, ceramic and mica.

44. Conductors • Electrons in the outer shell can become free by applying some sort of external force such as magnetic field, rubbing, or chemical action. • An electron that became free can move into an atom that just lost an electron. This way an electron can move from one atom to the next (just roaming around). • Substances allowing such movement of electrons are called conductors. • This movement of electrons is the basis of electricity.

45. Semiconductors • Substances that are both conductors and resistors under certain conditions. • We can make them either to conduct or to resist!! It is wonderful! • This is be principle behind transistors, diodes and other solid state devices. • A material that conducts electricity when exposed to light and resists when exposed to darkness is selenium. This semiconductor is known as a photoconductor.

46. How a photocopier works • Now that we talked about selenium, I can’t pass it up without talking about photocopiers. • Every copier and laser printers have an aluminum drum coated with positively charged selenium. • When kept in dark it keeps its pos charge. • When an image is shown (light and dark) on the selenium it becomes a conductor and sends its positive charge to the aluminum. • Now a negatively charged toner is wiped on the drum. The toner attaches to the positive areas on the aluminum. • A paper is passed against the drum and the paper gets the toner. Then the paper passes through high heat and the toner is fused on the paper.

47. More on Resistors • Resistors can be made from carbon particles mixed with a binder material. • Resistance is measured in Ohms or K or M-Ohms. • Rating is calculated using the color bands. BlBROYGBVGrW. • First two band are numerals and third indicate zeros. • VVO – 77000 Ohms • Symbol

48. Resistor color code

49. Copper Wire as a conductor • Electric current in copper wire is the flow of electrons, but these electrons are not supplied by the power source. • They come from the wire. • Batteries and generators do not create these electrons, they merely pump them, and the electrons are like a pre-existing fluid that is always found within all wires.

50. Electrons in the copper wire • Recall the copper atom? • One electron from the outer shell just roam around. • If we direct the flow in the same direction then we have current. • Current is measured in Amps. Means how many electrons pass by a fixed point in a second (coulomb per second). • Electrons flow from negative to positive.