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HP 50g issue - Printable Version

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HP 50g issue - Matthew Richards - 04-18-2013

I purchased an HP 50g a few weeks ago and I'm getting comfortable with it. One strange thing that annoys me is a long pause during simple math (usually division operations or entering a number into the stack). I start to work the math and all the sudden the calculator pauses for a few seconds (up to 10 seconds!). At first I thought I wasn't hitting the keys hard enough, but if I hit the key again, I get two operations. I then started looking for the hourglass when it acts up. If I see the hourglass, I wait. I could understand if it was calculating a limit of an improper integral, but division! Is there something wrong with this calculator or is it in some kind of mode that it's estimating out too far? I usually keep it in real and estimate mode. I haven't been able to determine if complex/real and/or exact/estimate mode are the issue. I usually don't have time to pay attention (in the middle of an exam or trying to get homework done in a short period of time). I bought a 35s today and I'm using it for now until I can figure out why my 50g is so slow.

Re: HP 50g issue - Michael de Estrada - 04-18-2013

I've got mine set with Flag 103 set (Complex On) and Flag 105 set (Approximate mode on) with no delays.

Re: HP 50g issue - Chris Smith - 04-18-2013

Mine did this once. I did an On+F6 then ON to reboot. Has been ok since. Alternatively yank a battery out for a few seconds.

From a programming perspective it feels like it's out of memory and/or the garbage collector is buggy. Occasionally it does pause so I assume its doing a collection run or something. I know nothing about the internals so I could be wrong.

Re: HP 50g issue - Joe Horn - 04-19-2013

> At first I thought I wasn't hitting the keys hard enough, but if I hit the key again, I get two operations.

Aha, that sounds like the infamous HP 50g "Busy Bug". If you press a key at *exactly* the moment that the busy annunciator turns off, then that keystroke gets stored in the key buffer but is not executed until the next system interrupt, such as the next keystroke.

This causes exactly the behavior you described: It seems that a keystroke was missed (nothing happens), but then the next keystroke performs BOTH keystrokes.

There's a easy workaround for the Busy Bug: Just set flag -40 (which turns on the ticking clock display in the status area). When that flag is set, a system interrupt occurs every second (to update the clock), which releases any keystroke that may have been frozen by the Busy Bug. So if a keystroke seems to do nothing when it should have, just wait a maximum of one second and it'll activate. The annoyance is not eliminated, but it's greatly reduced, because you no longer have to wonder whether a keystroke was ignored; within one second, you'll know for sure.

Hope that helps!


Re: HP 50g issue - Matthew Richards - 04-21-2013

Oddly, I turned the clock on recently, because it's nice to have, and it hasn't acted up. Maybe that did it. I'm using it more right now to understand some different uses for the Taylor series and graphing quite a bit, so hopefully I'll know if it's gone soon. Thanks for all the advice!