Int 15 Fn CA  U - Ps/2 Model 95 - Read/write Cmos Memory                   [B]

   AH = CAh
   AL = function
       00h read CMOS

       Return: CL = value of CMOS location
       01h write CMOS
       CL = new value for CMOS location
   BL = CMOS location (0Eh-3Fh)

Return: CF clear if successful
       AH = 00h
   CF set on error
       AH = error code (see #0454)

Note:  writes do not update the CMOS checksum

(Table 0454)
Values for CMOS read/write error code:
 01h   CMOS lost power or has invalid checksum
 03h   specified location out of range (too high)
 04h   specified location out of range (too low)
 80h   unsupported function (PC)
 86h   unsupported function (XT)