Week 1 - Digital Systems: From Logic Gates to Processors

Graded quiz 1

Question 1 Which of the following statements are true? Check all that apply.

    Any block in a digital circuit can be described  hierarchically until a level of simplicity that allows its synthesis using a predefined catalog of components is achieved.
    Any digital system can be specified using a functional description or a structural description.

Question 2 In a stress test for elite athletes a physical system is used to measure the performance of the individual. Indicate which of these signals are analog signals:

    VO2 => Type: Liters/minute; Range: [2-7.5l/ min].
    Activity level (accelerometer) => Type: Current, Range: [0-7 mA]
    02 Saturation => Type: Voltage, Range: [1-5 mV]
    Performance = Type: Real number; Range: [0-1]

Question 3 Following the previous question, indicate which of the following signals are digital signals.

    Heart rate  ⇒ Type: Numeric;  Range: Integers from 35 to 300
    Respiratory Rate ⇒ Type: Numerical; Range: integers from 8 to 40.
    Alarm ⇒ Type: Binary digit; Range: {0,1}.

Question 4 Consider the following structural description. Check which blocks are digital systems.

    B
    D
    E
    F

Question 5 The pseudocode shown in figure functionally describes the chronometer of lesson 2.1.The update procedure updates the values of h, m, s and t whenever a clock pulse arrives (ref_positive_edge signal). Which of the following pieces of pseudocode correctly implement the update procedure?. Mark all that apply.

    t <= t + 1;
    if t = 10 then t <= 0; s <= s + 1; end if;
    if s = 60 then s <= 0; m <= m + 1; end if;
    if m = 60 then m <= 0; h <= h+1; end if;
    if h = 24 then h <= 0; end if;

    t <= t + 1;
    if t = 10 then t <= 0;add_one_second <= 1;
              else add_one_second <= 0;
    end if;
    s <= s + add_one_second;
    if s = 60 then s <= 0; add_one_minute <= 1;
              else add_one_minute <= 0;
    end if;
    m <= m + add_one_minute;
    if m = 60 then m <= 0; add_one_hour <= 1;
              else add_one_hour <= 0;
    end if;
    h <= h + add_one_hour;
    if h = 24 then h<= 0; end if;

Question 6 Consider a system with three input signals: ref, a square wave with a period of 1 microsecond(1), and two natural number a and b The system generates a square wave, f, with period equal to (a + b) microseconds, as shown in figure. Which of the following algorithms describe the system? (1) Variable "ref_positive_edge" takes the value TRUE when a positive edge of signal "ref" arrives, and FALSE otherwise.

    loop
    f <= 1; count <= a;
    while count > 0 loop
          if ref_positive_edge = TRUE then count <= count - 1;
          end if;
    end loop;
    f <= 0; count <= b;
    while count > 0 loop
          if ref_positive_edge = TRUE then count <= count - 1;
          end if;
    end loop;
    end loop; 

Question 7 Mark the correct statement:

    The voltage levels defining the logical 0 and 1 depend on the circuit supply voltage.

Question 8 Fill in the above table so that it describes the behavior of the following circuit:

(Enter the 0s and 1s separated by a blank. For example, if the result was the one shown below, the answer should be 0 0 1 1 0 0 1 0)

    NA

Digital Systems: From Logic Gates to Processors