=== RTC Registers ===
00h Second (00..59) Registers 00H-09H in BCD mode: {| class="wikitable" style="text-align:center;\" 01h |-! ADDRESS !! BIT 7 !! BIT 6 !! BIT 5 !! BIT 4 !! BIT 3 !! BIT 2 !! BIT 1 !! BIT 0 !! FUNCTION !! RANGE|-| 00H || 0 || colspan="3" | 10 Seconds || colspan="4" | Seconds || Seconds || 00–59|-| 01H || 0 || colspan="3" | 10 Seconds || colspan="4" | Seconds || Seconds Alarm second (00..59) ; these ten registers can be BCD or Binary|| 00–59 02h Minute (00..59) ; (see Control B, Bit2|-| 02H || 0 || colspan=DM)"3" | 10 Minutes || colspan="4" | Minutes || Minutes || 00–59 03h |-| 03H || 0 || colspan="3" | 10 Minutes || colspan="4" | Minutes || Minutes Alarm minute (00..59) ;|| 00–59 04h Hour (00..23) ; ;\|-| 04H || AM/PM || 0 || 0 || 10 Hours || colspan="4" | Hours || Hours || 1–12 +AM/PM<br>00–23|-| 05H || AM/PM || 0 || 0 || 10 Hours || colspan="4" | Hours || Hours Alarm || 1–12 +AM/PM<br>00–23|-| 06H || 0 || 0 || 0 || 0 || 0 || colspan="3" | Day || Day || 01–07|-| 07H || 0 || 0 || colspan="2" | 10 Date || colspan="4" | Date || Date || 01–31|-| 08H || 0 || 0 || 0 || 10 Months || colspan="4" | Month || Month || 01–12|-| 09H || colspan="4" | 10 Years || colspan="4" | Year || Year || 00–99|} Registers 00H-09H in 24hour binary mode: 05h Alarm hour (00..23) ; {| class="wikitable" style="text-align:center;"|-! ADDRESS !! BIT 7 !! BIT 6 !! BIT 5 !! BIT 4 !! BIT 3 !! BIT 2 !! BIT 1 !! BIT 0 !! FUNCTION !! RANGE|-| 00H || 0 || 0 || colspan="6" | Seconds || Seconds || 00–3B|-| 01H || 0 || 0 || colspan="6" | Seconds || Seconds Alarm || 00–3B|-| 02H || 0 || 0 || colspan="6" | Minutes || Minutes || 00–3B|-| 03H || 0 || 0 || colspan="6" | Minutes || Minutes Alarm || 00–3B|-| rowspan="2" | 04H || AM/bit7PM || rowspan="2" | 0 || rowspan="2" | 0 || 0 || colspan="4" | Hours || rowspan="2" | Hours || rowspan="2" | 01–0C +AM/PM<br>00–17 06h Day of week (01..07) ;|- 07h | 0 || colspan="5" | Hours|-| rowspan="2" | 05H || AM/PM || rowspan="2" | 0 || rowspan="2" | 0 || 0 || colspan="4" | Hours || rowspan="2" | Hours Alarm || rowspan="2" | 01–0C +AM/PM<br>00–17|-| 0 || colspan="5" | Hours|-| 06H || 0 || 0 || 0 || 0 || 0 || colspan="3" | Day (01..31) ;|| Day || 01–07 08h |-| 07H || 0 || 0 || 0 || colspan="5" | Date || Date || 01–1F|-| 08H || 0 || 0 || 0 || 0 || colspan="4" | Month (01..12) ;|| Month || 01–0C 09h |-| 09H || colspan="8" | Year (00..99) ;/|| Year || 00–63|} Control registers:
0Ah Control A
7 UIP Update in Progress (0=Stable in next 244us, 1=Time changes) (R)
7 VRT Valid RAM and Time (1=Okay, 0=Battery Low) (R)
6-0 0 Reserved (zero)
Non-Volatile RAM:
0Eh..3Fh battery backed RAM (HD146818, DS1287A, DS12887A and other chips)
40h..7Fh battery backed RAM (only on DS12887A and newer chip variants)
80h..FFh reserved
== Other chips ==