Introduction to Digital Systems – Exercise – 2

66. A DAC changes ________.

(a) an analog signal into digital data
(b) digital data into an analog signal
(c) digital data into an amplified signal
(d) none of the above

67. In a certain digital waveform, the period is four times the pulse width. The duty cycle is ________.

(a) 0%
(b) 25%
(c) 50%
(d) 100%

68. A periodic digital waveform has a pulse width (tw) of 6 ms and a period (T) of 18 ms. The duty cycle is ________.

(a) 3.3%
(b) 33.3%
(c) 6%
(d) 18%

69. The output of a NOT gate is HIGH when ________.

(a) the input is LOW
(b) the input is HIGH
(c) the input changes from LOW to HIGH
(d) voltage is removed from the gate

70. If a HIGH logic level is assigned a binary zero (0), and a low level is assigned a binary one (1), the logic is called ________.

(a) negative logic
(b) positive logic
(c) invalid logic
(d) assertion-level logic

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