MDU
                           Version 1.1

                          Gene Pizzetta
                          June 22, 1990


MDU is a tiny ZCPR3 utility to set or display the maximum drive 
and user (MAXDU) in the environment descriptor.  It was written 
to test software and to allow reconfiguration of my drive system 
without creating a new ENV file.  It might also be useful for 
RCP/M's.

USAGE:

     MDU {d}{u}{:}

Sets maximum drive and/or user in the environment descriptor to 
the given value (A-P, 0-31).  A following colon is optional.  If 
no parameters are given, MDU displays current maximum drive and 
user.

If the quiet flag is set, the current maximum DU is reported if 
MDU is called with no parameters; otherwise, only error messages 
will be displayed.  If the wheel byte is reset (off), the current 
status is displayed, but the MAXDU bytes in the environment are 
not changed.

If the given drive or user is out of the permitted range, the 
program error flag will be set to 2 (invalid directory).  If the 
command line is invalid, the error flag will be set to 4 (unknown 
error).  In either case the error handler is invoked, if one is 
running.

HISTORY:

Version 1.1 -- June 22, 1990 -- Gene Pizzetta
     Fixed bug that caused error handler to be invoked when quiet
     flag was set.  (Thanks to Howard Goldstein.)  Added wheel
     byte support.  If wheel byte is reset, displays current
     maximum drive/user, but changes nothing.

Version 1.0 -- June 17, 1990 -- Gene Pizzetta
     Original release.