INT 21 P - FlashTek X-32VM - SET SELECTOR BASE ADDRESS
        AX = 3503h
        BX = selector
        ECX = base address
Return: CF clear if successful
        CF set on error (invalid selector)
Note:   there are probably additional 35xxh functions, but the message
          containing the FlashTek calls was truncated in transit and the
          remaining information did not arrive prior to release