(*******************************************************************
Procedure to abort process in case of error; with message.
*******************************************************************)
procedure Abort ( S : string ) ;
begin
   writeln ( 'Message : ' , S , #7#7#7 ) ;
   Halt ( 1 ) ;
end ;
(*******************************************************************
Convert string to upper case.
*******************************************************************)
function Upper ( S : string ) : string ;
var
   temp                      : string ;
   B                         : byte ;
begin
   temp                      := S ;
   for B := 1 to length ( S ) do
      temp [ B ]             := UpCase ( temp [ B ] ) ;
   Upper                     := temp ;
end ;
(*******************************************************************
Returns a byte for the drive letter, where 1 thru 26 = A: thru Z:
*******************************************************************)
function DriveNum ( S : string ) : byte ;
begin
   DriveNum                  := 0 ;
   if pos ( ':' , S ) <> 2 then EXIT ;
   DriveNum                  := ord ( UpCase ( S [ 1 ] ) ) - 64 ;
end ;
(*******************************************************************
Check that this program is an EXE file AND is on drive A:
*******************************************************************)
function IsDriveA ( S : string ) : boolean ;
begin
   IsDriveA                  := DriveNum ( S ) = 1 ;
end ;