CMOS-RAM & RealTime Clock (AT) MC146818

Index Register (070h)

Data Registers (071h)

Address Meaning
00h Seconds
01h Alarm-Seconds
02h Minutes
03h Alarm-Minutes
04h Hours
05h Alarm-Hours
06h Day of Week
07h Day
08h Month
09h Year
0Ah - 0Dh Status Registers A - D
0Eh Diagnosis status-byte
0Fh Interupt
10h Disk Type A: & B:
11h Reserved
12h Disk Type C: & D:
13h Reserved
14H Configuration byte
15h - 16h RAM Size low/high
17h - 18h Expansion RAM Size low/high
19h - 2Dh Reserved
2Eh - 2Fh CMOS-RAM Checksum
30h - 31h Extended RAM Size
32h Century for date
33h Power-on flags
34h - 3Fh Reserved