The Dobbertin Smart Watch was produced by Dobbertin Industrie Elektronik, a German company. This real time clock was relative wide spread in the 80ies and 90ies.
Technicals
The SmartWatch consists out of the RTC itself and an EPROM expansion with a lot of RSX commands. The RTC itself was inserted like an EPROM in any kind of ROM or EPROM card. Further it contains a little battery. At least one clock is still running in 2014!
Dallas Semiconductors SmartWatch
The 28pin SmartWatch (DS1216) is an adapter that can inserted in standard ROM sockets, a ROM chip can be mounted on the adapter, finally, inside of the adapter is a 16pin Phantom Time Chip (DS1315). Normal memory reads are forwarded to the piggyback ROM. After reading from a specific sequence of addresses, the ROM is disabled, and data is instead read from the Phantom Chip via 1bit databus. Writing to the Phantom Chip is done by reading from a specific sequence of addresses, too.
- Dallas DS1315 16pin Phantom Time Chip
- Dallas DS1216 28pin Smart Watch datasheet
- Dallas DS1216 Application Note
64bit packets
Accessing the RTC is done by following steps
- Read 1 or more bits (this resets the recognition pattern; best read at least 64 bits, in case the chip was in the 64-bit data read phase)
- Write the 8-byte (64bit) recognition pattern
- Read or Write the 8-byte (64bit) register data
The 8-byte (64bit) pattern/data is transferred serially, LSB first. The used bits on address and databus are:
A2 data direction (0=write, 1=read) A0 data written to RTC, when A2=0=write D0 data read from RTC, when A2=1=read, and only when pattern recognized
Note: Writes to the RTC chip can be performed by using Z80 reads (PEEK). All that matters is the A2 and A0 address lines.
Recognition Pattern
The recognition pattern is: C5h, 3Ah, A3h, 5Ch, C5h, 3Ah, A3h, 5Ch.
The Dobbertin chip requires 64 sequential writes with magic serial data on A0 to unlock it, immediately followed by 64 sequential reads to retrieve the 64-bit time data packet from D0, after which the chip locks itself back into ROM mode.
Real-Time Clock Registers
| Register | Bit Position | Range (BCD) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | ||
| 0 | 0.1 SEC | 0.01 SEC | 00–99 | ||||||
| 1 | 0 | 10 SEC | SECONDS | 00–59 | |||||
| 2 | 0 | 10 MIN | MINUTES | 00–59 | |||||
| 3 | 12/24 | 0 | AM/PM | 10 HOUR | HOUR | 01–12 | |||
| 10 HOUR | 00-23 | ||||||||
| 4 | 0 | 0 | /OSC | /RST | 0 | DAY | 01–07 | ||
| 5 | 0 | 0 | 10 DATE | DATE | 01–31 | ||||
| 6 | 0 | 0 | 0 | 10 MONTH | MONTH | 01–12 | |||
| 7 | 10 YEAR | YEAR | 00–99 | ||||||
Legend:
- /OSC controls the oscillator. When set to "0", the oscillator turns on and the real time clock begins to increment
- When the /RST bit is set to "0", a low input on the reset pin of the chip will cause the Time Chip to abort data transfer without changing data in the timekeeping registers
Pictures
The original RTC from Dobbertin.
The DXS RTC is a Dobbertin RTC clone. Source
The expanded version from DXS.
Downloads
- TIME ROM+ ROM file
- MF2_RRB.DSK - Vortex disc, containing the TimeRom+ CP/M driver
Software
- The TimeROM Software provides RSX commands to use the RTC under BASIC.
- Support for CP/M Plus is provided. The TIMEROM+.COM program sets the software clock according to the RTC. Please use the patched versions of DATE.COM, DIR.COM, SETDEF.COM and SHOW.COM (Y2K Patch).
- TFM's TIMEROM#.COM supports ROM slots 0-127 now.
- TFM provided some routines here.
- The Smart Watch is supported by FutureOS, SymbOS and HDCPM. Source
- The Smart Watch is emulated in WinApe and MAME.
The option to emulate the Dobbertin Smartwatch in WinAPE can be found in Settings/Other/Other devices:
