User manual
DIGITAL-LOGIC AG    MSB900/L Detailed Technical Manual V1.0 
30 
CMOS Map 
Location  Description 
00h  Time of day (seconds) specified in BCD 
01h  Alarm (seconds) specified in BCD 
02h  Time of day (minutes) specified in BCD 
03h  Alarm (minutes) specified in BCD 
04h  Time of day (hours) specified in BCD 
05h  Alarm (hours) specified in BCD 
06h  Day of week specified in BCD 
07h  Day of month specified in BCD 
08h  Month specified in BCD 
09h  Year specified in BCD 
0Ah  Status Register A 
Bit 7  =  Update in progress 
Bits 6-4  =  Time based frequency divider 
Bits 3-0  =  Rate selection bits that define the periodic 
interrupt rate and output frequency. 
0Bh  Status Register B 
Bit 7  =  Run/Halt 
  0  Run 
  1  Halt 
Bit 6  =  Periodic Timer 
  0  Disable 
  1  Enable 
Bit 5  =  Alarm Interrupt 
  0  Disable 
  1  Enable 
Bit 4  =  Update Ended Interrupt 
  0  Disable 
  1  Enable 
Bit 3  =  Square Wave Interrupt 
  0  Disable 
  1  Enable 
Bit 2  =  Calendar Format 
  0  BCD 
  1  Binary 
Bit 1  =  Time Format 
  0  12-Hour 
  1  24-Hour 
Bit 0  =  Daylight Savings Time 
  0  Disable 
  1  Enable 
0Ch  Status Register C 
Bit 7  =  Interrupt Flag 
Bit 6  =  Periodic Interrupt Flag 
Bit 5  =  Alarm Interrupt Flag 
Bit 4  =  Update Interrupt Flag 
Bits 3-0 =  Reserved 
0Dh  Status Register D 
Bit 7  =  Real Time Clock 
  0  Lost Power 
  1  Power 
  Continued... 










