What is concurrent and sequential in VHDL?

What is concurrent and sequential in VHDL?

The primary concurrent statement in VHDL is a process statement. A number of processes may run at the same simulated time. Within a process, sequential statements specify the step-by-step behavior of the process, or, essentially, the behavior of an architecture. The process statement is itself concurrent statement.

What are concurrent and sequential statements?

Whenever one of the signals in the sensitivity list changes, the sequential statements are executed in sequence once. In contrast, signal assignment statements inside architecture bodies that are not contained in processes (or body) are called concurrent statements.

What is concurrency theory?

Concurrency Theory is a synthesis of one of the major threads of theoretical computer science research focusing on languages and graphical notations for describing collections of simultaneously evolving components that interact through synchronous communication.

What is concurrency example?

Concurrency is the tendency for things to happen at the same time in a system. Figure 1: Example of concurrency at work: parallel activities that do not interact have simple concurrency issues. It is when parallel activities interact or share the same resources that concurrency issues become important.

Which is concurrent statement?

Concurrent statements are used to define interconnected blocks and processes that jointly describe the overall behavior or structure of a design. Concurrent statements execure asynchronously with respect to each other.

What is a concurrent statement?

Concurrent statements are used to define interconnected blocks and processes that jointly describe the overall behavior or structure of a design. Concurrent statements execure asynchronously with respect to each other. The language does not define the order, if any, in which such statements will be executed.

When do you create a Concurrent statement in VHDL?

When you create a concurrent statement, you are actually creating a process with certain, clearly defined characteristics. Concurrent statements are always equivalent to a process using a sensitivity list, where all the signals to the right of the signal assignment operator are on the sensitivity list.

Which is the conditional signal assignment statement in VHDL?

Now let’s take a look at two concurrent signal assignment statements in VHDL: “the selected signal assignment statement” and “the conditional signal assignment statement”. Consider an n -to-one multiplexer as shown in Figure 3.

Is the VHDL a combinatorial or sequential programming language?

You may think the VHDL is a hardware description language, this means that when you write a statements you are coding the implementation of a combinatorial or sequential logic. If you keep in mind this concept, it will be clear that VHDL code is concurrent and not sequential as classical programming languages.

Which is a characteristic of a VHDL architecture?

VHDL Concurrency. One of the major VHDL characteristics is the concurrency. In typical programming languages such as C++ or Visual Basic, the code is executed sequentially following the order of the statement in the source files. Inside a VHDL architecture there is no specified order in the assignment statement.