Int 15 Fn DA20  U - Ami Pci Bios V1.00.12.ax1t - Cmos Ram Bitfield Manipu  [b]

   AX = DA20h
   BL = subfunction
       00h set CMOS data field
       BH = CMOS data field number (00h-4Dh)
       CH = new value for bitfield (in lowest bits of register)
       01h read CMOS data field
       BH = CMOS data field number (00h-4Dh)

       Return: CH = value of bitfield
           CL = mask of valid bits

       Note:   both CL/CH shifted to move valid bits into lowest pos
       02h set CMOS byte
       CL = CMOS RAM address (00h-7Fh)
       CH = new value for CMOS byte
       03h get CMOS byte
       CL = CMOS RAM address (00h-7Fh)

       Return: CH = value of CMOS byte
       04h update CMOS checksums

       Note:   sets 2Eh/2Fh to checksum of 10h-2Dh and 7Eh/7Fh to
             checksum of 48h-7Dh
       05h verify CMOS checksums

       Return: CF clear if checksums OK
               AH = 00h
           CF set if checksum mismatch
               AH = 01h

Return: CF clear if successful
       AH = 00h
   CF set on error
       AH = error code (86h unsupported function/data field)

Notes: this function was not supported by the v1.00.05.AX1 BIOS, but had been
     added by 1.00.12.AX1T
   after using subfunctions 00h or 02h, the application must call
     subfunction 04h to update the checksums to prevent an error the next
     time the system is booted

(Table 0466)
Values for AMI BIOS v1.00.12.AX1T CMOS bitfield identifier:
 ID    address bit(s)  contents
 00h   1Ah 7-6
 01h   1Dh 7-6
 02h   6Eh 1
 03h   77h 0
 04h   77h 1
 05h   77h 2
 06h   77h 3
 07h   77h 5
 08h   77h 6
 09h   77h 7
 0Ah   78h 7   power management enabled???
 0Bh   78h 6
 0Ch   10h 7-4 first floppy drive type
 0Dh   10h 3-0 second floppy drive type
 0Eh   11h 7
 0Fh   20h 4-0 selected language for error messages/setup utility
 10h   11h 2-1
 11h   11h 4
 12h   11h 0
 13h   11h 3
 14h   13h 7
 15h   13h 6-5
 16h   13h 4-2
 17h   19h 7
 18h   19h 6
 19h   19h 5
 1Ah   19h 4
 1Bh   1Eh 2-0
 1Ch   1Bh 7-6
 1Dh   1Ch 7
 1Eh   1Ch 3
 1Fh   1Ah 5-4
 20h   1Dh 5-4
 21h   1Bh 5-4
 22h   1Ch 6
 23h   1Ch 2
 24h   1Ah 3-2
 25h   1Dh 3-2
 26h   1Bh 3-2
 27h   1Ch 5
 28h   1Ch 1
 29h   1Ah 1-0
 2Ah   1Dh 1-0
 2Bh   1Bh 1-0
 2Ch   1Ch 4
 2Dh   1Ch 0
 2Eh   50h 7-0
 2Fh   51h 7-0
 30h   52h 7-0
 31h   53h 7-0
 32h   60h 0
 33h   60h 0
 34h   60h 0
 35h   60h 0
 36h   60h 0
 37h   60h 0
 38h   60h 1
 39h   61h 7
 3Ah   60h 2
 3Bh   61h 6-4
 3Ch   61h 2-0
 3Dh   60h 7-6
 3Eh   60h 5-4
 3Fh   78h 5-4
 40h   6Eh 5
 41h   1Eh 3
 42h   6Eh 0
 43h   6Eh 2
 44h   6Fh 1-0
 45h   6Fh 1-0
 46h   28h 4-2
 47h   28h 7-5
 48h   6Eh 4
 49h   6Eh 3
 4Ah   76h 7-0
 4Bh   77h 4
 4Ch   11h 6
 4Dh   1Fh 7-0