6818 RTC (HD146818) ========== +--------+--------------------------------------------------------------------------+ |Register| | +========+==========================================================================+ | 0 | Clock Seconds 00-59 or &00-&59 | +--------+--------------------------------------------------------------------------+ | 1 | Alarm Seconds 00-59 or &00-&59, or &C0-&FF for 'any' | +--------+--------------------------------------------------------------------------+ | 2 | Clock Minutes 00-59 or &00-&59 | +--------+--------------------------------------------------------------------------+ | 3 | Alarm Minutes 00-59 or &00-&59, or &C0-&FF for 'any' | +--------+--------------------------------------------------------------------------+ | 4 | Clock Hours 00-23 or &00-&23 | +--------+--------------------------------------------------------------------------+ | 5 | Alarm Hours 00-23 or &00-&23, or &C0-&FF for 'any' | +--------+--------------------------------------------------------------------------+ | 6 | Day of the week 01-07 or &01-&07, 1=Sunday | +--------+--------------------------------------------------------------------------+ | 7 | Day of the month 01-31 or &01-&31 | +--------+--------------------------------------------------------------------------+ | 8 | Month 01-12 or &01-&12 | +--------+--------------------------------------------------------------------------+ | 9 | Year 00-99 or &00-&99 | +--------+--------------------------------------------------------------------------+ | 10 | Register A b7: UIP Update In Progress b3: RS3 \ | | | b6: DV2 \ Clock b2: RS2 Rate Selection | | | b5: DV1 } Divider b1: RS1 Setting | | | b4: DV0 / setting b0: RS0 / | +--------+--------------------------------------------------------------------------+ | 11 | Register B b7: SET Clock being set b3: SQE Squarewave Enable | | | b6: PIE Periodic IRQ Enable b2: BIN 0=BCD, 1=BIN | | | b5: AIE Alarm IRQ Enable b1: 24H 0=12hr 1=24hr | | | b4: UIE Update IRQ Enable b0: DSE USA Daylight Saving | +--------+--------------------------------------------------------------------------+ | 12 | Register C b7: IRQ Any IRQ pending b3: 0 | | | b6: PF Periodic IRQ b2: 0 | | | b5: AF Alarm IRQ b1: 0 | | | b4: UF Update IRQ b0: 0 | +--------+--------------------------------------------------------------------------+ | 13 | Register D b7: VRT Valid RAM & Time b3: 0 | | | b6: 0 b2: 0 | | | b5: 0 b1: 0 | | | b4: 0 b0: 0 | +--------+--------------------------------------------------------------------------+ | 14 to | User available RAM | | 63 | | +========+==========================================================================+