Difference between revisions of "RTC"
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Usage in [[SYMBiFACE II:Realtime clock]]: | Usage in [[SYMBiFACE II:Realtime clock]]: | ||
| − | Uses a Dallas | + | Uses a Dallas DS12887A RTC chip, mapped to ports: |
FD14h SYMBiFACE II Real Time Clock - DS1287A RTC Data (R/W) | FD14h SYMBiFACE II Real Time Clock - DS1287A RTC Data (R/W) | ||
FD15h SYMBiFACE II Real Time Clock - DS1287A RTC Index (W) | FD15h SYMBiFACE II Real Time Clock - DS1287A RTC Index (W) | ||
Revision as of 07:51, 31 March 2025
Contents
PC compatible RTC chip
Usage in CPCs
Usage in SYMBiFACE II:Realtime clock:
Uses a Dallas DS12887A RTC chip, mapped to ports: FD14h SYMBiFACE II Real Time Clock - DS1287A RTC Data (R/W) FD15h SYMBiFACE II Real Time Clock - DS1287A RTC Index (W) RAM at [32h] is "attempted" to be used as century.
Usage in Dk'tronics Real Time Clock:
Uses a HD146818 chip. Details on I/O addresses are unknown. Unknown if century is supported.
Usage in Aleste 520EX - I/O Ports:
Uses a russian KR512WI1 chip (which is, according to the Aleste's Manual) compatible to western MC146818 chips. Connects to a 32.768kHz crystal. Connects to the PPI: PPI Port A.Bit0-7 = Data bus PPI Port C.Bit0 = Read/Write (0=Write, 1=Read) PPI Port C.Bit1 = Index Access (0=No, 1=Access) PPI Port C.Bit2 = Data Access (0=No, 1=Access) In the Aleste's Ext Port, the RTC must be enabled, and PSG and 8253 must be disabled. Unknown if century is supported.
RTC Registers
00h Second (00..59) ;\
01h Alarm second (00..59) ; these ten registers can be BCD or Binary
02h Minute (00..59) ; (see Control B, Bit2=DM)
03h Alarm minute (00..59) ;
04h Hour (00..23) ; ;\in 24hour mode:
05h Alarm hour (00..23) ; ;/bit7=PM
06h Day of week (01..07) ;
07h Day (01..31) ;
08h Month (01..12) ;
09h Year (00..99) ;/
0Ah Control A
7 UIP Update in Progress (0=Stable in next 244us, 1=Time changes) (R)
6-4 DV Oscillator control (must be 2 for normal operation)
3-0 RS Rate Selector for IRQ pin (not used by SYMBiFACE II)
0Bh Control B
7 SET Stop clock, to be set/cleared before/after writing to [0h..9h]
6 PIE Periodic Interrupt Enable (see Control A, RS)
5 AIE Alarm Interrupt Enable
4 UIE Update-Ended Interrupt Enable (aka Seconds Interrupt)
3 SQWE Square-Wave Enable (see Control A, RS)
2 DM Data Mode for [00h..09h] (0=BCD, 1=Binary)
1 24H 24-Hour Mode (0=12h with AM/PM, 1=24h)
0 DSE Daylight Saving Enable (0=No, 1=Uses hardcoded timezone)
0Ch Control C (read-only, automatically reset to zero after reading)
7 IRQF Interrupt Request Flag (1 on PIE,AIE,UIE, 0 after read) (R)
6 PF Periodic Interrupt Flag (see Control A, RS) (R)
5 AF Alarm Interrupt Enable Flag (R)
4 UF Update-Ended Interrupt Flag (aka Seconds Interrupt) (R)
3-0 0 Reserved (zero)
0Dh Control D (read-only)
7 VRT Valid RAM and Time (1=Okay, 0=Battery Low) (R)
6-0 0 Reserved (zero)
0Eh..3Fh battery backed RAM (DS1287A, and other/newer chips)
40h..7Fh battery backed RAM (DS12887A, newer chip variants only)
80h..FFh reserved
32h battery backed RAM (commonly used as Century) (19..99) (see notes)
Century Notes
The DS12887A RTC chip used in the SYMBiFACE II does not have a century register. Whether the Aleste and Dk'tronics do have this register is unknown.
Other chips
- ACU Real Time Clock (DIY)
- Dobbertin Smart Watch
- URTC-8 Universal RTC for Z80 computers
- Nova (M48T35Y-70MH1F chip)
