function IsDriveReady(DriveLetter : char) : bool;
 
   var
 
     OldErrorMode : Word;
 
     OldDirectory : string;
 
   begin
 
     OldErrorMode := SetErrorMode(SEM_NOOPENFILEERRORBOX);
 
     GetDir(0, OldDirectory);
 
     {$I-}
 
     ChDir(DriveLetter + ':');
 
     {$I+}
 
     if IOResult <> 0 then
 
       Result := False
 
     else
 
       Result := True;
 
     ChDir(OldDirectory);
 
     SetErrorMode(OldErrorMode);
 
   end; { IsDriveReady }//Esempio di utilizzo:
 
if not IsDriveReady('A') then
 
     ShowMessage('Drive Not Ready')
 
else
 
     ShowMessage('Drive is Ready');