The Designer's Guide to VHDL, 2nd Edition

F Differences among VHDL-87, VHDL-93 and VHDL-2001

In this appendix we summarize the main differences among VHDL-87, VHDL-93 and VHDL-2001, many of which we mentioned throughout the book. Most new models will be written in VHDL-2001, since that is the current “official" version of the language. However, designers must deal with the legacy of models written in the old versions and with VHDL tools that have yet to be updated to handle the current version.

F.l Lexical Differences

VHDL-87 uses the ASCII character set, rather than the full ISO character set. ASCII is a subset of the ISO character set, consisting of just the first 128 characters. This includes all of the unaccented letters, but excludes letters with diacritical marks.

VHDL-87 only ...