INT 15 - EISA SYSTEM ROM - WRITE NONVOLATILE MEMORY
AX = D803h
CX = length of data structure (0000h = empty slot)
includes two bytes for config file checksum
DS:SI -> configuration data
Return: CF clear if successful
AH = 00h
CF set on error
AH = error code
84h error clearing CMOS
85h EISA CMOS is full
86h invalid BIOS-FW function call
Note:   call with AL=83h if using 32-bit CS addressing mode instead of 16-bit

See also: 15D802

15D803 - EISA SYSTEM ROM - WRITE NONVOLATILE MEMORY