The three defined data types in VHDL are access, scalar,
and composite. Note that VHDL 1076-1987 defined a fourth data
type, file, but files were reclassified as
objects in VHDL 1076-1993. In any case, files will not
be discussed in this module but will be covered in the 'System Level
VHDL' module included in this collection of educational modules.
Simply put, access types are akin to pointers in other
programming languages, scalar types are atomic units of
information, and composite types are arrays and/or records.
These are explained in more detail in the next few slides. In
addition, subtypes will also be introduced.
[Perry94], p. 74.
