Process Statement

VHDL

This set of VHDL Multiple Choice Questions & Answers (MCQs) focuses on “Process Statement – 1”.

1. Process is a _______ statement.
a) Concurrent
b) Sequential
c) Delay
d) Both concurrent and sequential

2. If there is more than one process in a VHDL code, How they are executed?
a) One after the other
b) Concurrently
c) According to sensitivity list
d) Sequentially

3. A process has a declaration part.
a) True
b) False

4. Local variables in a process can be declared __________
a) Anywhere within the process
b) After a sequential statement
c) Before the BEGIN keyword
d) After the BEGIN keyword

5. Which of the following is correct syntax for process declaration?
a)

     {Label :} PROCESS
     {process_declaration_part};
      sensitivity_list;
     BEGIN
     sequential_statements;
     END PROCESS {Label};

b)

     PROCESS {sensitivity_list}
     {process_declaration_part}
     BEGIN
     sequential_statements;
     END PROCESS {Label};

c)

     {Label :} PROCESS
     {process_declaration_part}
     BEGIN
     sensitivity_list;
     sequential_statements;
     END PROCESS;

d)

     {Label :} PROCESS {sensitivity_list}
     {process_declaration_part}
     BEGIN
     sequential_statements;
     END PROCESS {Label};

6. Sensitivity list of a process contains __________
a) Constants
b) Signals
c) Variables
d) Literals

7. Which of the following statement is used when there are no signals in the sensitive list?
a) WHEN
b) IF ELSE
c) WAIT
d) CASE

8. What is the effect of the sensitivity list on the process?
a) Process executes when any of the signal in sensitivity list changes
b) Process executes sequentially when sensitivity list is specified
c) If there is no sensitivity list, then the process will not execute
d) Helps in simulation

9. It is mandatory to use a label for any process.
a) True
b) False

10. If no signal in the sensitivity list is changed, then how many times the process will be executed?
a) 3
b) 2
c) 1
d) 0

11. Which of the following statements can be seen as sequential equivalent to the selected concurrent assignment?
a) IF ELSE
b) WAIT
c) WHEN
d) CASE

12. A __________ can’t be declared inside a process.
a) Signal
b) Variable
c) Constants
d) Subprograms

13. It is possible to use sensitivity list and wait statements in the same process.
a) True
b) False

14. The process can be __________ by using WAIT statements.
a) Suspended
b) Resumed
c) Suspended as well as resumed
d) Cannot be determined

15. A postponed process runs when ___________
a) All the other processes have completed
b) After completion of one particular process
c) Concurrently with all other processes
d) First of all processes

16. Which of the following statement can’t be used inside a process?
a) WAIT
b) IF ELSE
c) Variable declaration
d) PORT MAP

17. Which of the following signal cause the process to execute?

PROCESS (clr)
BEGIN
IF (clr = ‘1’) THEN
y <= ‘0’;
ELSE
y <= input;
END PROCESS;

a) input
b) y
c) clr
d) x

18. The value of y is initially 1 and it is changed after one delta cycle to 0. How many delta cycles (starting from the beginning) will be taken to change the initial value of z, refer to the process given below?

PROCESS (y)
BEGIN
x <=y;
z <= NOT y;
END PROCESS

a) 1
b) 2
c) 3
d) 4

19. A combinational process must have all the _________ signals in its sensitivity list.
a) Input
b) Output
c) Declared
d) Used

20. There is no restriction on the number of wait statements inside a process.
a) True
b) False

21. Which of the following circuit can’t be described without using a process statement?
a) Multiplexer
b) D flip-flop
c) Decoder
d) Comparator

22. Which of the following signal uses keyword EVENT?
a) Variables
b) Output
c) Input
d) Clock

23. Refer to the code given below, what kind of circuit is designed?

SIGNAL x : IN BIT;
SIGNAL y : OUT BIT;
SIGNAL clk : IN BIT;
PROCESS (clk)
BEGIN
IF (clk’EVENT and clk = ‘1’)
y ;&lt= x;
END PROCESS

a) Buffer
b) Latch
c) Flip flop
d) Shift Register

24. The driver(s) of signal y is _________

PROCESS ()
BEGIN
y <= ‘1’;
y <= x;
y <= z;
END PROCESS;

a) z
b) x
c) x and z
d) 1

25. The resolution function is needed to resolve the value of _______

PROCESS ()
BEGIN
y <= x;
y <= z;
END PROCESS;

a) z
b) y
c) x
d) No x, y and z

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