Int 15 Fn 2402  - System - Later Ps/2s - Get A20 Gate Status               [b]

   AX = 2402h

Return: CF clear if successful
       AH = 00h
       AL = current state (00h disabled, 01h enabled)
       CX = ??? (set to 0000h-000Bh or FFFFh by AMI BIOS v1.00.03.AV0M)
       FFFFh if keyboard controller does not become ready within C000h
            read attempts
   CF set on error
       AH = status
       01h keyboard controller is in secure mode
       86h function not supported

Notes: also supported by AMI PCI BIOS and Qualitas 386MAX v6.01+
   IBM classifies this function as optional

See Also: AX=2400h,AX=2401h