hang up in HP49G?


I have been using a HP49G for several months now, and am troubled when it appears to hang up for a few seconds (actually, it can be as long as 10 seconds). This even happens when doing the simplest of calculations. The calculator eventually catches up with my keystrokes, but it can be un-nerving. Is there a problem, and can I do anything about it?


hey andy
this is called "garbage collection"
it is a process the hp49 uses to clear the part of memory that stores return adresses to the rom of of the hp49. it is a normal part of the operation of the calculator. does the little hourglass appear while it is "thinking"? some operations cause it to occur for longer periods than other tasks like using large lists etc. if you have been performing "return address" intensive operations this could be why it is occurring (remember the processor is only 4megahertz not 466mhertz or whatever that u have on you desktop)

hope this helps


My HP49G also 'hangs' for a few moments when doing simple calculations. Even after only doing simple calculations all day. Why doesn't the HP49G do this background task between operations when the user would not notice it? Currently the calculator seems to wait until you start pressing the keys before doing it's background task, just at the time you want it to respond quickly! With the rubber keyboard this can be a real pain as sometimes I end up pressing the same key twice because it doesn't appear to have read the first one.

Also it's a bit silly when showing off what the HP49G can do to freinds when it can take a few seconds to calculate 2+2! (Perhaps they could use a lookup table for this calculation to speed it up?)


Turn off the on-screen clock. I t seems to improve. Have you upgraded the ROM? latest versions seem to be less prone to do this annoying Garbage Collection so often.


I does seem strange that the calculator does "garbage collection" at such strange times, e.g. during simple calcualtions. Because during simple calculations is when the hang-ups typically occur. I may have been doing some "return address" operations earlier in the day, but just didn't realize it (to be honest, I not exactly sure what "return address" operations are). Also, I will try turning off the clock display to see if this helps. Thanks.


hey Andy
sorry i couldn't give a more detailed answer. however the serious hp49g programmers mostly hang out at newsgroup comp.sys.hp48 there are many knowledgeable folk there experienced with the hp48 and hp49g (i would recommend postings by a guy called joe horn) this forum is excellent with the earlier makes and models but does not specialise in the hp49g

hope this helped


Thanks Paul, I will definitely check it out.

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