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Introduction
This chapter describes how GM VHDL can be used to model the operation of
digital hardware designs. This chapter and the following one assume the
use of VHDL'93. The chapter What's new in VHDL'93 describes the
differences between VHDL'93 and VHDL'87.
GM VHDL supports three techniques of modeling
the operation of a design
- structural
- This technique describes how components
(an and gate, for example) can be interconnected to model a design.
- data flow
- Like register transfer languages, this technique specifies
how data flows from the input signals to the output signals.
- behavioral
- A design using this technique would represent the design
as a sequential algorithm that computes the outputs of the design from the
inputs.
All of these techniques can also be used together in a single design.
The following three sections describe how a one-bit half adder could be
modeled differently using the three different modeling techniques.
Structural
Data Flow
Behavioral
Discrete event simulation