In computer programming, an entry point is a memory address,
corresponding to a point in the code of a computer program which
is intended as the destination of a long jump, be it internal or
external. Usage customs  In most of today's popular computer
systems, such as Microsoft Windows and Unix, a computer program
usually only has a single entry point. In C and C++ programs
this is the Historically, and in some contemporary legacy
systems, such as VMS and OS/400, computer programs have a
multitude of entry points, each corresponding to the different
functionalities of the program. The usual way to denote entry
points, as used system-wide in VMS and in PL/I and MACRO
programs, is to append them at the end of the name of the
executable image, delimited by a dollar sign ($) i.e.
directory.exe$make. The Apple 1 computer also used this to some
degree. For example an alternative entry point in Apple 1 BASIC
would keep the BASIC program useful when the reset button was
accidentally pushed. See also