== 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!
The Time-ROM can be on another ROM-select than the SmartWatch [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/real-time-clock-board/msg249697/#msg249697 Source].
[[SymbOS]] is searching for the TIME.SET RSX command. It will then use this ROM [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/real-time-clock-board/msg249768/#msg249768 Source].
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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 are performed by using Z80 reads (PEEK). All that matters is and the A2 and A0 address lines, with the SmartWatch mapped to memory and at addresses corresponding to where it is mapped.
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The recognition pattern is: C5h, 3Ah, A3h, 5Ch, C5h, 3Ah, A3h, 5Ch.
The Dobbertin RTC 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.
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== Pictures ==
The original RTC from Dobbertin:
[[File:DALLAS_DS1216.jpg]]
The original RTC from Dobbertin.
The DXS RTC is a Dobbertin RTC clone. [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/real-time-clock-board/msg249386/#msg249386 Source]
The DXS RTC is a Dobbertin RTC clone [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/real-time-clock-board/msg249386/#msg249386 Source]: [[File:RTCdxs.jpeg|720px500px]]The expanded version from DXS.
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* [[media:TIMEROM+.ROM|TIME ROM+]] ROM file
* [[media:MF2_RRB.DSK|MF2_RRB.DSK]] - Vortex disc, containing the TimeRom+ CP/M driver
* [[Media:DXS RTC - User Manual.pdf|DXS RTC User Manual]]
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