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HP Forum Archive 18

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Is it possible to turnOff HP-41 display?
Message #1 Posted by Matti Ívermark on 14 Dec 2007, 1:43 p.m.

Hi!

I wonder if there is any command for the 41-series that turns off the LCD while running a program. Obviously that kind of killed the display of a 41CV on a calc that a friend of mine has.

Anybody having a clue?

      
Re: Is it possible to turnOff HP-41 display?
Message #2 Posted by Gerry Schultz on 14 Dec 2007, 2:21 p.m.,
in response to message #1 by Matti Ívermark

No, there is no built-in function to turn off the display. When HP released the 41C, one of it's major selling points was that the multi-segment LCD display used very little power since it uses room light to illuminate its display as compared to the LED displays, which generate light on the 67 and 97. It's not really a good idea to turn off the display anyway as it's the only way to tell if the 41C is on or not. If the display could be blanked while running a program, then you would not know if the program was caught in a loop or had halted unexpectedly. Other than generating tones, the only way a 41C can communicate with you is through the display if you don't have a printer or some other peripheral connected.

Perhaps you could you change the flying goose character that is displayed during a running program to a null (blank character) using Synthetic or ML programming? There's still the annunciators in the bottom row. Do you want those off as well?

Gerry

            
Re: Is it possible to turnOff HP-41 display?
Message #3 Posted by Garth Wilson on 14 Dec 2007, 3:02 p.m.,
in response to message #2 by Gerry Schultz

Quote:
Perhaps you could you change the flying goose character that is displayed during a running program to a null (blank character) using Synthetic or ML programming? There's still the annunciators in the bottom row. Do you want those off as well?
If you don't even want the flying goose, clear alpha and do AVIEW. The PRGM annunciator will still be on at the bottom though, and possibly others, like USER, flags 0-4, etc..

In almost every HP-41 picture you see with alpha in the display, the ALPHA annunciator is on. I guess the people who take the pictures don't realize you can get out of alpha mode and do PROMPT to show the alpha register without having the ALPHA annunciator on!

      
Re: Is it possible to turnOff HP-41 display?
Message #4 Posted by Eric Smith on 14 Dec 2007, 5:12 p.m.,
in response to message #1 by Matti Ívermark

Even if you blank the display, it is still "on", and there are still AC voltages applied to it. However, this will not damage the display. LCDs generally don't suffer any measurable wear from use.

Backlights have a limited lifetime, but the 41C/CV/CX display doesn't have a backlight.

            
Re: Is it possible to turnOff HP-41 display?
Message #5 Posted by Matti Ívermark on 15 Dec 2007, 12:44 p.m.,
in response to message #4 by Eric Smith

OK, thanks all of you.

I shall try it. Thanks again!


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