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stevenfbowditch
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18 12 2 2
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HP Prime Calculator: no seconds display on clock, no decimal seconds from "Time" function, rate

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HP Prime Graphing Calculator

I am disappointed that the HP Prime Graphing Calculator does not have a seconds display on the clock.  Also, when the "Time" command is executed, the time is only displayed to the previous second, and no decimal seconds are displayed.  ADDITIONALLY, the clock does not appear to keep very good time, loosing several seconds with respect to other clocks in only ONE day.  All of these issues make the calculator difficult to use for timing.

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Maké
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Hi!, @Stevenfbowditch :

See, this link ... https://www.thecalculatorstore.com/Calculator-blog/Working-with-hours-min-and-seconds-in-HP-Prime

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
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stevenfbowditch
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This link provides a  neat way to convert from hms to decimal, but the other issues remain.

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Maké
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Hi!, @Stefenfbowditch :

You can see ...

HMS.JPG 

For reason of space, don't see in the display the format hh.mm.ss, but the ticks, run OK.

Kind Regards !.
Have a nice day !.
@Maké (Technical Advisor Premium - HP Program Top Contributor).
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
Tim_Wessman
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Hello,

 

Modern devices are generally NOT very good with time any more. This is becasue they are not designed as stopwatches and are designed with the idea that they will be synced with much more accurate external sources regularly. The clock is more then good enough for general time keeping, but will definitely not be accurate if you are looking for ms precision. Sorry about that.

 

The reason there is no seconds on the display is simple - space, and that it would have a significant battery drain impact. Unlike old monochrome calculators, you have to do significant work to update even a small area of the screen, and also wake the whole system up from its "off" state each second to redraw the screen. That would probably take more then 3/4 of the battery life of the system by doing that.

 

There is a second clock in the corner if you just tap that area, but it is not normally visible.

TW

Although I work for the HP calculator group as a head developer of the HP Prime, the views and opinions I post here are my own.
stevenfbowditch
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Thanks for the reply.  Do you know if the G2 version of the HP Prime improved the accuracy of the clock?  

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stevenfbowditch
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HI again:  I can probably use the clock if the RATE of gain or loss is constant.  Can you give me any idea if the millisecond ticks are reasonably stable or wandering?  If wandering, what is the reason for this?  Thanks

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cyrille
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Hello,

 

Prime has multiple clocks internally.

It has a "RTC", which stands for Real Time Clock. This is a peice of hardware whose job it is to keep time in sexadecimal format (60seconds, 60minutes, 24hours, n days per month, 12 days per year). These do know about leap year. The RTC has its own power supply to continue working even when the CPU is off and has it's own 12Khz cristal to count time. They are normally "accurate" to a second per day or so (at least in my experience)... This clock is what is used to keep the "time" on Prime, and it only counts in seconds.

The reason why the display has only the minutes, as explained by Tim is to keep space on the screen and to avoid having to redraw the screen every second. Saves power! The Time function, or a click on the clock (say that aloud:-) will give you second accuracy.

 

The calculator also has Ticks. These is a millisecond counter which is used internally for programming. This counter is handled by a completely different piece of hardware which is based on the much less accurate CPU clock (as in the CPU frequency). This Clock is not kept between CPU reboots and stops when the CPU turns off.

When you call the Ticks function, this is what is being used. It is suitable for program timing and any fast operations.

 

Cyrille

 

 

I am an HP Employee
stevenfbowditch
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Wow, thanks for the explanation.  I need to think about how all this affects my applications. 

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cyrille
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Hello,

 

Do not hesitate to ask more questions if you need more technical details.

Happy programming.

 

Cyrille

I am an HP Employee
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