The Designer's Guide to VHDL, 3rd Edition

Chapter 23. Miscellaneous Topics

In the preceding chapters we introduced most of the facilities provided by VHDL and showed how they may be used to model a variety of hardware systems at various levels of detail. However, there remain a few VHDL facilities that we have not yet discussed. In this chapter, we tie off these loose ends.

Guards and Blocks

In this section we look at a number of closely related topics. First, we discuss another kind of resolved signal called a guarded signal. We see how we can disconnect drivers from such signals. Next, we introduce the idea of blocks in a VHDL design. We show how blocks and guarded signals work together with guards and guard expressions to cause automatic disconnection of drivers. Finally, we discuss ...