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HP Forum Archive 02

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DANGER: 48/49 LCD with HP41 emu
Message #1 Posted by Daniel Diggelmann on 16 Apr 2000, 6:01 a.m.

Yesterday I was testing the micro code emulator for HP41C/CV/CX V1.3 on both HP48G and HP49G. I compared the behaviour with my real HP41CV. I was quite impressed by the compatibility. Even auto power off is implemented. I left the HP48 and HP49 for an hout or two on the table when I was working with the HP41. In the meantime both HP48/49 had powered off. First I powered up the HP48 up again and was really shocked when I saw some ugly stripes on the LCD. At first I was of the impression that it must have received a mechanical the shock or something. Then I turned on the HP49 which had even worse vertical stripes on its LCD. The coincidence was clearly due to that emulator. aaaarrrrgggg !!!!! Unbelievable ?!?! What has happened ??? My theory is that the emulator doesn't handle the LCD properly when turning off. The calculator isn't really off as the ON button is assigned to F6. So I suspect that the LCD gets DC instead of AC in in this mode. After a few minutes of working the stripes got a bit lighter on both machines. Seeing this reaction I tried to "reanimate" the LCDs by running graphic animations on both machines for several hours. Actually this helped. The HP48 seems fully recovered. Whereas the HP49 LCD doesn't show the stripes anymore but seems a bit sluggish since. The dots turn off with a visible delay. So I can just recommend not to fry your calc by running this software!!! I would even be careful with asm programs like grayscale viewers and the like. The programmers may not know what they're doing to the LCD. But this is just my personal safety precaution.

Cheers Daniel Diggelmann

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