Revision history
09-30-91    v2.00  Added support for DOOR.SYS, Updated the doc files,
                   Added .DAT file format to allow security and time
                   checking before allowing caller to open door.
07-01-91    v2.00  Beta started
07-16-90    v1.51  Compiled using ProKit 3.2 release, and add close down
                   door.
03-04-90    v1.5   Fixed dropped carrier problem, minimized opening screen
                   in registered versions.
02-26-90    v1.4   Added support for registered SysOps by popular request
01-01-90    v1.3   Compiled using Turbo Pascal 5.5, ProKit 3.1, and a minor
                   bug that caused an occasional door to return to the main
                   board on exit.
01-23-89    v1.2   Compiled using Turbo Pascal 5.0
01-05-89    v1.1   Minor bug fix in SysOp Display.  Added printer logging.
                   Now allows User-defined batch file name so DorMENU could
                   now be run from the PCB directory without conflict.
12-26-88    v1.0   Initial coding