When VHDL first came out as an IEEE standard, it was thought to be sufficient to
model hardware designs. Reality proved to be a little different. Because it did not
have a predefined four-state logic type, each simulator and model vendor had to
create its own—and incompatible—logic type. This situation prompted the quick
creation of a group to create a standard multi-valued logic package for VHDL that
culminated with the 1164 standard. With such a package, models became
interoperable and simulators could be optimized to perform well-defined operations.
The authors of this book hope to create a similar standard for verification components
within the SystemVerilog language. The infrastructure elements specified in the
appendices can form the basis of a standard verification interface. If model vendors
use it to build their verification components, they will be immediately interoperable.
If simulator vendors optimize their implementation of the standard functions, the
runtime performances can be improved.