Exec maintains lists of libraries and devices.  An Amiga library consists
of a collection of related functions which can be anywhere in system
memory (RAM or ROM).  An Amiga device is very similar to an Amiga library,
except that a device normally controls some sort of I/O hardware, and
generally contains a limited set of standard functions which receive
commands for controlling I/O.  For more information on how to use devices
for I/O, see the "exec device i/o" chapter of this book.

    Not for Beginners.
    ------------------
    This chapter concentrates on the internal workings of Exec
    libraries (and devices).  Most application programmers will not to
    know the internals workings of libraries to program the Amiga.  For
    an introduction to libraries and how to use them, see chapter one,
    "introduction to amiga system libraries".

 what is a library?    adding a library