Int 62 Fn 00E1  u - Fgdriver V4.02 - "fg_xalpha" - Convert Screen Column   [V]

   AX = 00E1h
   BX = screen space column

Return: AX = character space column containing specified coordinate

Note:  the FGDRIVER functions are rearranged with each major release, but
     their parameters do not change (see #3145 at AX=0000h)

See Also: AX=00E2h,AX=00E4h