VHDL borrows heavily from the Ada (programming language) in both concepts (for example, the slice notation for indexing part of a one-dimensional array) and syntax. VHDL has constructs to handle the parallelism inherent in hardware designs, but these constructs (processes) differ in syntax from the parallel constructs in Ada (tasks). Like Ada, VHDL is strongly-typed and case insensitive. There are many features of VHDL which are not found in Ada, such as an extended set of Boolean operators including nand and nor, in order to represent directly operations which are common in hardware.
(VHDL From Wikipedia, the free encyclopedia)