NAME
        BeginCardAccess -- Called before you begin credit-card memory access

   SYNOPSIS
        result=BeginCardAccess( handle )
        d0                      a1

        bool begincardaccess( struct cardhandle * );

   FUNCTION
        This function should be called before you begin access
        to credit-card memory.

        Its effect will depend on the type of Amiga machine your
        code happens to be running on.  On some machines it
        will cause an access light to be turned ON.

   INPUTS
        handle - Same handle as that used when owncard() was called.

   RETURNS
        TRUE if you are still the owner of the credit-card, and
        memory access is permitted.  FALSE if you are no longer
        the owner of the credit-card (usually indicating that
        the card was removed).

   NOTES
        This function may be called from within a task, or from a level 1
        or level 2 interrupt.

        It is highly recommended that you call this function
        before accessing credit-card memory, as well as checking
        the return value.  If it is a return value of FALSE, you
        should stop accessing credit-card memory.

   SEE ALSO
        owncard(), endcardaccess()