== 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) and the A2 and A0 address lines, with the TimeROM+ 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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