This set of VHDL Assessment Questions and Answers focuses on “All Keywords in VHDL – 2”.
1. When the keyword GUARDED is used, it is always mandatory that the statements inside will be executed concurrently.
Explanation: Since Guarded is always used with the BLOCK statement which itself is a block statement and contains concurrent statements. So, wherever we are using guarded, it means that the statement will be executed concurrently.
2. Among the following, with which keyword MAP is generally used?
Explanation: MAP is generally used with PORT for mapping of the components. PORT MAP statement is used for instantiation of the component after its declaration is being done.
3. Impure is a type of _______
a) Data type
Explanation: IMPURE keyword is used to define impure functions. An Impure function is a function which can return some different type given that the actual parameters are same.
4. How does keyword inertial affect an assignment statement?
a) By defining initial value from which delay should be started
b) To prevent overriding of following delay assignment statements
c) To specify wire delay
d) No effect
Explanation: Inertial delay is the default delay in VHDL. If the assignment statement is y <= x AFTER 10 ns; then it will be same as y <= INERTIAL x AFTER 10 ns; There is no difference between two given statements. So, adding inertial doesn’t affect the assignment.
5. Which of the following keyword must be used to specify wire delay?
Explanation: The Transport delay is analogous to the delay incurred by passing a current through a wire and therefore, it is also called wire delay. To specify the transport delay type in an assignment, the keyword TRANSPORT is used.
6. Which of the following is associated with the INOUT keyword?
a) Type of a signal
b) Mode of a signal
c) Name of a signal
d) Function of a signal
Explanation: INOUT is a kind of mode of a signal specified in any entity or architecture. The signal can have four modes- IN, OUT, INOUT and BUFFER. So, INOUT is a mode of signal which is used to specify the signal can be used as input as well as output type.
7. The word LABEL is not reserved in VHDL.
Explanation: LABEL is also a reserved word in VHDL. However, we can write the name of label in starting of any specific statement. But, LABEL itself is a reserved word used for specify a label name in an attribute statement.
8. What is LINKAGE keyword associated with?
Explanation: LINKAGE keyword is associated with signals in VHDL. It is used to link VHDL ports with non-VHDL ports. This corresponds to the mode of a signal and is used when we need to connect VHDL design to some non-VHDL ports.
9. LINKAGE keyword is same as _______ mode.
Explanation: LINKAGE is same as INOUT mode of a signal. In case of LINKAGE, we can use the signal as we can use it in INOUT mode. There is no difference between LINKAGE and INOUT modes of a signal.
10. MOD keyword is a ________
a) Data type
Explanation: MOD is the modulus operator which can be used on two integer operands. It is actually an arithmetic operator which can be applied to integer types only. It returns the remainder after dividing first operand by the second operand.
Sanfoundry Global Education & Learning Series – VHDL.
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