Name: Class: Date: 1. As more electronic systems have been designed using digital technology, devices have become smaller and less powerful.

Transcription

1 Name: Class: Date: DE Midterm Review 2 True/False Indicate whether the statement is true or false. 1. As more electronic systems have been designed using digital technology, devices have become smaller and less powerful. 2. A digital audio system makes a copy of the waveform. 3. A digital audio system stores a code, a series of amplitude numbers, that tells the compact disc player how to re-create the original sound every time a disc is played. 4. The binary number system is a positional notation system. 5. Hexadecimal numbers are primarily used as a shorthand form of binary notation. 6. The logical sum is the same as the arithmetic sum. 7. Not every chip requires power and ground. 8. The NOT function has one input and one output. 9. TTL and CMOS devices differ not in their logic functions, but in their construction and electrical characteristics. 10. For the NAND gate we can say all inputs HIGH make the output HIGH. 11. When grouping terms for simplification, every pair of terms must have at least one term that belongs only to that pair. 12. The number of cells in a K-map (Karnaugh map) is always a power of 2, usually 4, 8, or The more digital components or gates used inside a circuit, the more difficult it might be to simplify the circuit. 14. In a K-map, a cell should never be grouped more than once. 15. Most digital circuits require multiple gates. 1

2 Name: Multiple Choice Identify the choice that best completes the statement or answers the question. 16. Typically, _ vary between two discrete values in much the same way that a light switch has two levels, off and on. a. analog signals c. digital signals b. continuous voltages d. frequency modulations 17. The signal on a CD is sampled _ times each second. a. 4,100 c. 100,400 b. 44,100 d. 104, Assigning the digit 1 to a logic HIGH and digit 0 to logic LOW is called _.. a. negative logic c. positional notation b. positive logic d. amplification 19. The hexadecimal number system is based on powers of _. a. 4 c. 16 b. 8 d A momentary variation of voltage from one logic level to the opposite level and back again is called _. a. pulse width c. amplitude b. aperiodic waveform d. pulse 21. The rightmost bit of a binary number is the: a. rising edge c. rising and falling edge b. least significant bit d. most significant bit 22. Which of the following terms does NOT apply to digital signals? a. Continuously variable c. Numbers b. Discrete steps d. Microprocessors 23. A _ system is a system of writing numbers where the value of a digit depends not only on the digit, but also on its placement within a number. a. positional notation c. trailing edge b. decimal number d. frequency 24. After the binary system, numbers are the most often used in digital applications. a. decimal c. hexadecimal b. digital logic d. digital 2

3 Name: 25. is the fraction of the total period that a digital waveform is in the HIGH state. a. Frequency c. Time HIGH b. Duty cycle d. Time LOW 26. is a time-varying sequence of logic HIGHs and LOWs that repeats over a specified period of time. a. Time LOW c. Aperiodic waveform b. Time HIGH d. Periodic waveform 27. A special case of a symmetrical periodic waveform is a: a. duty cycle c. clock signal b. pulse width d. digital waveform 28. is a system in which logic LOW represents binary digit 1 and logic HIGH represents binary digit 0. a. Logic level c. Negative logic b. Positive logic d. Digital logic 29. A truth table is a list of output levels of a circuit corresponding to all different: a. input combinations c. timing diagrams b. input digital circuits d. frequencies 30. For the binary numbers from 0000 to 1111, the decimal equivalents are _. a. 0 to 10 c. 1 to 15 b. 0 to 15 d. 1 to How many basic logic functions are there that can be combined to make any other logic?. a. two c. six b. four d. three 32. A gate can be categorized by examining three attributes: output, input, and. a. size c. shape b. function d. logical sum 33. Electronic device that conducts current in one direction only and illuminates when it is conducting, describes a: a. digital signal c. light-emitting diode b. control switch d. V CC 34. A dual in-line package (DIP) has two parallel rows of pins; the standard spacing between pins in one row is. a. 0.1" (or 100 mil) c. 0.4" (400 mil) b. 0.3" (or 300 mil) d. 0.6" (600 mil) 3

4 Name: 35. A medium-scale integration is an integrated circuit having the equivalent of gates in one package. a. 12 to 100 c. 100 to 10,000 b. 100 to 1,000 d. 120 to 10, is a circuit board in which connections between components are made with lines of copper on the surfaces of the circuit board. a. A breadboard c. Printed circuit board b. An integrated circuit d. Wire-wrap 37. The only place a chip gets its required power is through the: a. V CC pin c. J-lead b. dual in-line package (DIP) d. small outline IC 38. can be used as electronic switches to block or allow passage of digital waveforms. a. Tristate buffers c. SPST switches b. Logic gates d. Inverting buffers 39. A(n) _ gate combines all of its inputs in an AND function, then inverts the total result. a. OR c. NOT b. NOR d. NAND 40. An is shown by a bubble or an arrow symbol on the affected terminal. a. active HIGH c. active LOW b. inversion d. opposite logic level 41. When inverting gates such as NAND and NOR are enabled, they will invert an input signal passing it to the gate output; in other words, they transmit the signal in. a. complement form c. small-scale integration b. high-impendance state d. large-scale integration 42. _ is a sophisticated technology that relies on automatic placement of chips and soldering of pins onto the surface of a circuit board, not through holes in the circuit board. a. TSSOP c. TTL b. QFP d. SMT 43. A(n), also called a NOT gate, is a logic gate that changes its input logic level to the opposite state. a. difference gate c. bubble b. coincidence gate d. inverting buffer 4

5 Name: 44. Digital data are transferred from more than one source to one or more destinations along a common wire or _. a. chip c. bus b. pin d. wire-wrap 45. A is list of all possible input values to a digital circuit, listed in ascending binary order, and the output response for each input combination. a. data book c. truth table b. datasheet d. Multisim file 46. is the process of creating a logic circuit from a description such as a Boolean equation or truth table. a. Synthesis c. Simplification b. Sum-of-products d. Product-of-sums 47. When designing a combinational logic circuit, you are ultimately looking for a: a. K-map simplification c. Boolean equation b. NAND function d. logic gate network 48. A(n) is a group of eight adjacent cells. a. maxterm c. octet b. quad d. minterm 49. A combinational logic circuit is one in which two or more gates are connected together to combine several: a. levels of gating c. double-rail inputs b. Boolean inputs d. DeMorgan equivalents 50. There are two ways of labeling cell coordinates: (1) numerically or (2) by: a. groups c. true and complement variables b. the buble-to-bubbel convention d. cell groups 51. A yellow light, called the ALERT light, illuminates when: a. two or more sensors indicate an out-of-range condition b. no sensors are out of range c. no more than one sensor indicates an out-of-range condition d. all sensors are out of range 52. The input to a circuit has values from coded in binary format. a. 1 to 3 c. 1 to 5 b. 0 to 3 d. 0 to 6 5

6 Name: 53. Boolean functions are governed by: a. an unsimplified Boolean expression c. adjacent cells b. cell content d. an order of precedence 54. When two or more gates are connected together they form a:. a. sequential logic c. logic gate network b. combinational logic d. combinatorial logic 55. Which of the following is an example of a product term? a. c. b. d. 56. is a sum term in a Boolean expression where all possible variables appear once, in true or complement form. a. Product term c. Sum-of-products b. Maxterm d. Product-of-sums 57. One way to simplify a is to look for pairs of product terms that are different by just one variable, then factor out what is common to the term, as you would do in other types of algebra. a. truth table c. Multisim problem b. word problem d. sum-of-products 58. A(n) is a variable around the edge of a K-map that represents an input variable (e.g., A, B, C, or D) for the Boolean expression to be simplified. a. cell coordinate c. adjacent cell b. quad d. octet 59. The maximum simplification of a Boolean expression is achieved only if the circled groups of cells in its K-map are and there are as few groups as possible. a. small c. in pairs b. as large as possible d. single 60. is the practice of drawing gates in a logic diagram so that inverting outputs connect to inverting inputs and noninverting outputs connect to noninverting inputs. a. Order of precedence c. Sequential logic b. Bubble-to-bubble convention d. Combinatorial logic Short Answer 61. Electronic systems and devices are often divided into two areas; please name them. 6

7 Name: 62. Using the analogy of a light switch versus a dimmer switch, which one best describes the digital signal and which one the analog signal? 63. What does the word bits refer to? 64. What are the two commonly used methods to convert decimal numbers to binary? 65. What is the main difference between analog and digital electronics? 66. Can you name the so-called Boolean functions that are the basis for all further study of combinational logic circuitry? 67. What does the acronym SPST stand for? 68. What is the simple rhyme that can help you remember how to use DeMorgan s theorems? 69. What does the acronym PDF stand for? 70. What is a Boolean variable? 71. How would you describe a Karnaugh map? 72. This chapter outlines three guidelines that apply when simplifying Boolena expressions. Can you describe at least one of the guidelines? 73. A green light, indicating that a system is functioning normally, is generally designated by what expression? 74. What are double-rail inputs and in what forms are they available? 75. There are two basic ways to find a truth table from a logic diagram. You can examine the output of each gate in the circuit and develop its truth table, then use your knowledge of gate properties to combine these intermediate truth tables into the final output truth table. Alternatively, you can develop a Boolean expression for the logic diagram by examining the expression, then filling in the truth table in a single step. Please explain the benefits and drawbacks, if any, for each of these methods. 7

8 DE Midterm Review 2 Answer Section TRUE/FALSE 1. ANS: F 2. ANS: F 3. ANS: T 4. ANS: T 5. ANS: T 6. ANS: F 7. ANS: F 8. ANS: T 9. ANS: T 10. ANS: F 11. ANS: T 12. ANS: T 13. ANS: F 14. ANS: F 15. ANS: T MULTIPLE CHOICE 16. ANS: C 17. ANS: B 18. ANS: B 19. ANS: C 20. ANS: D 21. ANS: B 22. ANS: A 23. ANS: A 24. ANS: C 25. ANS: B 26. ANS: D 27. ANS: C 28. ANS: C 29. ANS: A 30. ANS: B 31. ANS: D 32. ANS: C 33. ANS: C 34. ANS: A 35. ANS: A 36. ANS: C 1

9 37. ANS: A 38. ANS: B 39. ANS: D 40. ANS: C 41. ANS: A 42. ANS: D 43. ANS: D 44. ANS: C 45. ANS: C 46. ANS: A 47. ANS: C 48. ANS: C 49. ANS: B 50. ANS: C 51. ANS: A 52. ANS: B 53. ANS: D 54. ANS: C 55. ANS: D 56. ANS: B 57. ANS: D 58. ANS: A 59. ANS: B 60. ANS: B SHORT ANSWER 61. ANS: Electronic systems and devices are often divided into two areas: analog and digital electronics. 62. ANS: The digital signal can be compared to a light switch, whereas the analog signal can be more aptly compared to a dimmer switch. 63. ANS: Bits stands for binary digits. 64. ANS: Those methods are: (1) sum of powers of 2 and (2) repeated division by 2. 2

10 65. ANS: The main difference between analog and digital electronics is that analog voltages or currents are continuous between values, whereas digital voltages or currents are discrete (or allowed only at distinct levels). 66. ANS: All digital logic functions can be synthesized by various combinations of three basic logic functions, the so-called Boolean functions, which are: AND, OR, and NOT. 67. ANS: SPST is a single-pole single-throw switch. 68. ANS: You can remember how to use DeMorgan s theorems by the simple rhyme: Break the line and change the sign. 69. ANS: A PDF or portable document format is a format for storing published documents in compressed form. 70. ANS: A Boolean variable is a variable having only two possible values, such as HIGH/LOW, 1/0, On/Off, or True/False. 71. ANS: A Karnaugh map can be described as (1) a graphical tool for finding the maximum SOP or POS simplification of a Boolean expression and/or (2) a graphical tool for simplifying Boolean expressions that use a similar idea and/or (3) a square or rectangle divided into smaller squares called cells, each of which represents a line in the truth table of the Boolean expression to be mapped. 72. ANS: When simplifying Boolean expressions, the following guidelines apply. 1. Each term must be grouped with another, if possible. 2. When attempting to group all terms, it is permissible to group a term more than once. 3. Each pair of terms should have at least one term that appears only in that pair. 73. ANS: A green light is designated by OK. 3

11 74. ANS: Double-rail inputs are Boolean input variables that are available to a circuit in both true and complement form. 75. ANS: The former method is more thorough and probably easier to understand when learning the technique. The latter method is more efficient, but requires some practice and experience. 4