AX = FD00: Find Logical Page and Offset for filename

• Input: AX = 0FD00h
  ES:BX = Address of filename
  The filename is an array of 11 bytes, with the primary portion the filename in the 8 bytes (blank-filled) and the filename extension in the last 3 bytes (blank-filled).
  DL = 0 (i.e., drive A)

• Output: if NC, BX = 16K logical page, CX = offset in that 16K page
  if CY, filename was not found