HP50g - very inaccurate clock?


I can't find any answer on this by searching.

The internal clock on my 50g is not maintaining accurate time by a large factor.

At 17:00 today, I set the clock.

At 23:00 today, it had already lost 1 min 12 secs !!!

During that time, the calc was off.

What the heck is going on here?!?!?! I only got this machine the other day and the batts are fresh.

Is there a history of inaccurate clocks in the 50g? Or have I just lucked out here?




there were threads about this issue in comp.sys.hp48 , and maybe here, too.




Mine is about three hours in advance, but I don't remember the last time I set the time on it (probably three months ago). For timekeeping I never found anything better than my cheap Casio watch (2889 HDD-600), +/- 3 seconds/year but I might just have been lucky as the manual states +/- 30second/month.

Wolfgang Rautenberg's Timeman might be an option. It works nicely on my HP-49G. (I haven't tried it on the 50g yet).




I've noticed the same thing. I wrote a tiny program that adjusts for daily clock skew, and the calculated offset on my 50g is probably a few orders of magnitude greater than on my 48GX.

I use a 48G for an alarm clock, so I need accurate timekeeping. :)


Wow, that's strange. I just checked mine and it's only 5 minutes slow after seven months.


The only perfectly accurate clock is a dead one-- it's exactly right twice per day. All others are off by some margin- some more than others. :-)



I have used both the HP48 & HP50 as stop watches for sun observations. As a Surveyor I have to determine accurate true North. The method I use requires accurate time. You have to determine the watch error at the time of observation. This can be done on both calculators. I have found both to be reliable.


On my 48 GX, time is off around 1 second per day. This can be fixed by an alarm program that runs daily. Works perfectly. Even after weeks or even months, the time on my 48 is accurate within several seconds.

On the 50 G this is completely different. I got mine 2 months ago. And it seems that the daily offset is not constant. With CLKADJ I don't manage to adjust the clock within 0.2 seconds. On the 48 I do manage. At the moment I'm trying Timeman. But when the offset is not constant, that program will fail too.

I think the only "workaround" is to write an approximative CLKADJ program and to check the 50 G time always when it must be accurate.

HP do something. You are crippling your wonderful products because of bugs, bad emulation (what a horror), etc.

Programming firmware no longer is an art. Too sad.


Thanks for all the replies.

I am quite happy to accept a tolerance of about a couple of seconds a day for clock accuracy. Both my 48G calcs are actually better than this.

However, I am not prepared to accept the level of accuracy being shown in my 50G which is currently losing about 5 minutes a day. That is completely ridiculous and I am going to negotiate a refund or replacement from the dealer.

Yes, I can write a simple clock adjust program running off an alarm but it boggles the mind that this should be necessary on what is currently HP's top calc and in theory, one of the best calcs ever made.

The sad thing is that after the huge disappointment of the 35s and now this fiasco with the 50g, can I trust any new HP calc? I've said before that I consider the 48GX to be the last great true HP calc but I never expected it would retain that mantle because its replacement has fundamental problems such as not being able to keep time!

One of the reasons I bought the 50g was to use a style of programming that the 48GX doesn't quite have enough speed for and that style of programming is dependent on clock accuracy.

What an utter huge disappointment all of this is.



My 2003 HP49g+ is pretty consistent, dropping 1.7 seconds/day.

My 2007 HP50g is pretty consistent, dropping 2.1 seconds/day.

My HP48 units are not any better.

I wish the HP50g clock had a SETAF function like my HP-41CX, which gains only a few seconds each month when SETAF is properly set. I instead use a repeat-once-per-day ALARM program \<< 17200 CLKADJ DROP OFF \>> that adds 2.1 seconds (17200 ticks) to the clock. (The well-known erratic behavior of the HP49/50 ALARM function does cause some problem with regularity of activation.)

Edited: 14 Sept 2009, 6:42 p.m.


What else are you running on the calculator? This is pure speculation, but it's possible that the interrupt routine that updates the clock is low priority, so if some higher priority code is running for long enough, the calculator may skip updating the clock periodically.

As I said, this is pure speculation though.



Reading this thread, I decided to check my 48G and 50G. I used BBC1 terletext clock as reference.

After 8 days:
48G: lost 11 secs
50G: lost 17 secs.

The 48G was used occasionally for simple calculations and the 50G wasn't used at all. Temperature probably between 15 to 25 celcius.


My 50G is right now 7 minutes slow. That in about a year and a half. It's not accurate but it's typical of the 50 I think.
With my 2 41's and by adjusting the accuracy factor I could get them to be accurate within a few seconds a year.


That's about a loss of 0.8 seconds per day. That's better than I've ever heard about in a HP49g+/HP50g.

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