INT 15 U - newer PS/2; various BIOSes - GET CPU TYPE AND MASK REVISION
        AH = C9h
        AL = 10h (may be required on some non-PS BIOSes)
Return: AH = 00h
        CH = CPU type
            03h 80386
            04h 80486
        CL = mask revision
            23h 386SX
Notes:  the BIOS must save DX at startup in order to be able to support this
          call; PS/2 Models 56, 57, 90, and 95 are known to support it
        the PS/2 BIOS merely reads CMOS locations 190h (type) and 191h (rev)