Int 15 Fn 4604  - Compaq Contura 486 And "alladin" 08/05/93 ROMS - Get ??  [b]

   AX = 4604h

Return: CF clear if successful
       AL = byte read from I/O port 03F8h
   CF set on error (not supported)
       AH = 86h (unsupported function)

Note:  also supported by 7/26/93 LTE Lite 386 ROM