DISKTOTAL()
 Determines the total capacity of a floppy or hard disk
------------------------------------------------------------------------------
 Syntax

     DISKTOTAL([<cDrive>]) --> nTotalSpace

 Argument

     <cDrive>  Designates the drive for which memory capacity is
     determined.  The default is the current drive.

 Returns

     DISKTOTAL() returns a value that corresponds to the total capacity of
     the data carrier in the selected drive.  The default is the current disk
     drive.

 Description

     DISKTOTAL() determines if the capacity of the disk in use is sufficient
     for back up.  The advantage of DISKTOTAL() over any capacity determined
     by the system, is that it recognizes bad sectors and does not include
     them.

 Example

     Determine if disk capacity is sufficient:

     nRequired  :=  DBFSIZE()
     IF DISKTOTAL("A") < nRequired
        ? "Error! Insufficient disk capacity!"
     ENDIF