Int 14 Fn 1F  - X00 Fossil - Extended Serial Port Status/control           [S]

   AH = 1Fh
   DX = port number
   AL = direction
       00h read modem control register

       Return: BL = modem control register (see #0275)
           AH = status
       01h write modem control register
       BL = modem control register (see #0275)

       Return: AX = status

Notes: this function is intended to exactly emulate the PS/2 BIOS AH=05h call
   X00 forces BL bit 3 set (interrupts cannot be disabled)

See Also: AH=00h,AH=05h"SERIAL"

Bitfields for X00 FOSSIL modem control register:
Bit(s) Description (Table 0275)
 0 data terminal ready
 1 request to send
 2 OUT1
 3 OUT2 (interrupts) enabled
 4 LOOP
 5-7   reserved