


        Figure 1--CMOS RAM Data Descriptions
        
        Real time clock data
        
        Offset    Size      Description
        00        1 Byte    Current second in BCD
        01        1 Byte    Alarm second in BCD
        02        1 Byte    Current minute in BCD
        03        1 Byte    Alarm minute in BCD
        04        1 Byte    Current hour in BCD
        05        1 Byte    Alarm hour in BCD
        06        1 Byte    Current day of week in BCD
        07        1 Byte    Current day in BCD
        08        1 Byte    Current month in BCD
        09        1 Byte    Current year in BCD
        
        Status registers (See Figure 1)
        Offset    Size      Description
        0A        1 Byte    Status Register A
        0B        1 Byte    Status Register B
        0C        1 Byte    Status Register C
        0D        1 Byte    Status Register D
        
        
        Configuration data
        
        Offset    Size      Description
        0E        1 Byte    Diagnostic Status
                            Bit 1     = 1 Real time clock lost power
                            Bit 6     = 1 CMOS checksum is bad
                            Bit 5     = 1 invalid configuration  informa-
                                          tion found at POST
                            Bit 4     = 1 Memory  size compare  error  at 
                                          POST
                            Bit 3     = 1 Fixed  disk or  adapter  failed 
                                          initialization
                            Bit 2     = 1 CMOS time invalid
                            Bits 1-0  = Reserved
        
        0F        1 byte    Reason for shutdown
                            00  = Power on or reset
                            01  = Memory size pass
                            02  = Memory test pass
                            03  = Memory test fail
                            04  = POST end: boot system
                            05  = JMP doubleword pointer with EOI
                            06  = Protected tests pass
                            07  = Protected tests fail
                            08  = Memory size fail
                            09  = INT 15h Block Move
                            0A  = JMP doubleword pointer without EOI
        
        10        1 Byte    Diskette Drive Types
                            Bits 7-4  = Diskette drive 0 type
                                        0000b = No drive
                                        0001b = 360K drive
                                        0010b = 1.2 MB drive
                                        0011b = 720K drive
                                        0100b = 1.44 MB drive
                            Bits 3-0  = Diskette drive 1 type
        11        1 Byte    Reserved
        12        1 Byte    Fixed Disk Drive Types (0 = no drive)
                            Bits 7-4  = Fixed Disk drive 0 type
                            Bits 3-0  = Fixed Disk drive 1 type
                            NOTE:   These drive types do not  necessarily 
                            correspond with the values stored at 
                            locations 19h and 1Ah.
        13        1 Byte    Reserved
        14        1 Byte    Equipment installed
                            Bits 7-6  = Number of diskette drives
                                        00b = 1 Diskette drive
                                        01b = 2 diskette drives
                            Bits 5-4  = Primary display
                                        00b = Reserved
                                        01b = 40x25 color
                                        10b = 80x25 color
                                        11b = 80x25 monochrome
                            Bits 3-2  = Reserved
                            Bit 1     = 1 Math coprocessor installed
                            Bit 0     = 1 Diskette drive installed
        15        1 Byte    Base memory in 1K, low byte
        16        1 Byte    Base memory in 1K, high byte
        17        1 Byte    Expansion memory size, low byte
        18        1 Byte    Expansion memory size, high byte
        19        1 Byte    Fixed disk drive 0 type
        1A        1 Byte    Fixed disk drive 1 type
        1B-2D     19 Bytes  Reserved
        2E        1 Byte    Configuration information checksum--high byte
        2F        1 Byte    Configuration information checksum--low byte
        30        1 Byte    Actual expansion memory size--low byte
        31        1 Byte    Actual expansion memory size--high byte
        32        1 Byte    Century in BCD
        33        1 Byte    Information flag
                            Bit 7     = 1 128  KByte expanded memory  is 
                                        present
                            Bit 6     = 1 Setup flag (?)
                            Bits 5-0  = Reserved
        34-3F     12 Bytes  Reserved
