Language Elements of VHDL

• VHDL is a strongly typed language.
– Designers have to declare the type before using it.

• VHDL is not case sensitive ( but avoid mixed cases as a good programming practice)

• VHDL supports a wide variety of data types and operators.
– OBJECTS
– OPERATORS
– AGGREGATES

Objects

• They are used to represent and store the data in the design being described.

• Object contains a value of specific type.


This results in an object called COUNT that holds INTEGER value that belongs to class SIGNAL.

• The name given to the object is called as identifier.

• Do not use reserved words as identifiers.

• Each object has a data type and class.

• Class indicates how the object is used in the module and what can be done with that object.

• Type indicates what type of data the object contains.

• Each object belongs to one of the following class:
– CONSTANT
– SIGNAL
– VARIABLE
– FILES



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