__Operators in VHDL:__

There are four several types of built-in-operators:

**1. Logical Operators:** The logical operators NOT, AND, OR, NAND, NOR, and XOR can be used with any bit type or bit-vectors. When it is used as operators on bits, they have their usual meaning. When it is used as bit-vectors, the bit-vectors must have the same number of elements, and the operation is performed bitwise.

**2. Arithmetic Operators:** The typical arithmetic operators are available for integers, such as **+, -, *, /**. Although these operations are not built-in for bit-vectors, they are often provided in libraries that come with VHDL software. They are used with bit-vectors by interpreting them as a binary representation of integers, which may be added, subtracted, multiplied, or divided.

**3. Relational Operators:** Also predefined is the normal relational operators. They are =, /=, <, > and have their usual meanings (/=denotes the not equal operator). The result of all these operators is a Boolean value (TRUE or FALSE). The arguments to the =and /= operators may be of any type. The arguments of the <, <=, >, >= operators may be any scalar type (integer, real and physical types) or the bit-vector type. If the arguments are bit-vectors, then the arguments must be the same length and the result is TRUE only if the relation is true for each corresponding element of the array arguments.

**4. Concatenation Operators:** The & operator is a built-in VHDL operator that performs the concentration of bit-vectors.