Hardware Description Languages (HDL)

Definition

Types

VHSIC Hardware Description Language (VHDL)

• VHSIC means Very High Speed Integrated Circuit
• Originally developed under funding from the department of defense
• Originally meant for describe and document, not synthesize hardware

Verilog

• Developed by the industry same time as VHDL
• Gateway Design Automation
• Syntactic roots in “C”

Others

• System C: design extensions to C++
• System Verilog: an extension of Verilog including all of Verilog and object-oriented extensions for verification

Behavioral vs. Structural

Behavioral description: specifies the design at algorithmic level without associating to any specific physical parts, components, or implementations.

• $C=A+B$

The behavioral description is often also called the register transfer level, or RTL.

Structural description: specific components or specific implementations of components are associated with the design.

• Adder implementation using AND-OR gates
• Adder using XOR gates