Carl Fredrik Ahl Posted June 11, 2019 Share Posted June 11, 2019 Hi, I have a Garmin Instinct watch. When I press one of the buttons I come to a place where I can choose to set alarm, timer, stop watch etc. It will remember what I did last and show that when I get to the that place again. For example, if I use the alarm, the alarm will be displayed first. How does the watch save this even when it's turned off? It can't stay in RAM if the watch is turned off right? Link to comment Share on other sites More sharing options...
Sensei Posted June 11, 2019 Share Posted June 11, 2019 (edited) It's stored on some kind of non-volatile memory https://en.wikipedia.org/wiki/Non-volatile_memory e.g. Arduino has RTC module. You can read current time of real-time clock (RTC), write it, but can also read and write NVM which is on it. It's not much, just 56 bytes. (the rest (8 bytes) are used by time & date). Edited June 11, 2019 by Sensei 1 Link to comment Share on other sites More sharing options...
Christopher Posted June 13, 2019 Share Posted June 13, 2019 I don't know the internals of that part but some processors have a hibernate mode where some tiny amount of energy maintains the memory, even for years on a tiny battery. 1 Link to comment Share on other sites More sharing options...
StringJunky Posted June 13, 2019 Share Posted June 13, 2019 13 minutes ago, Christopher said: I don't know the internals of that part but some processors have a hibernate mode where some tiny amount of energy maintains the memory, even for years on a tiny battery. You're probably thinking of the cmos battery. Link to comment Share on other sites More sharing options...
MigL Posted June 13, 2019 Share Posted June 13, 2019 Some 'flash' memory will be retained for quite a while ( decades ); even without battery back-up. ( think USB storage sticks or SSDs ) 1 Link to comment Share on other sites More sharing options...
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