LCD contrast on halfnuts


I recently got my first 41 CX after 20 years of using CV (still good and in use) but it arrived without manuals. After a MASTER CLEAR, LCD resets to contrast 3 or 4 on a scale 0-15 what is a bit pale for my eyes. Is there a way to change the contrast on a halfnut LCD from the keyboard using some key combination, such as SHIFT ON for displaying time, instead of CTRST function from Sandbox ROM - the only one I know of that deals with LCD contrast setting.


Hi Miki,

I only know of HEPAX and SandBox for HalfNut contrast control, others may exist though. And yes, the default setting is certainly poor... it is set to 5 in a 0-15 range. Fortunatelly you only need to set it once and it's "remembered" even if a MEMORY LOST is achieved.

To my eyes (literally) the best setting is 7 or 8... but this is a personal choice anyhow... ;-)




I don't know how to do that contract setting on my halfnut; can someone tell me hw to dot it?



Angel Martin's Sandbox ROM has a few functions that can read, set, increment contrast settings of a halfnut's LCD on the scale 0-15. You can get Sandbox only if you have Clonix and put it into two of its six available pages. Digeo says that Hepax has similar function. If you have Hepax then you are among few lucky ones. It does seem that once you set the contrast it is remembered even after a master clear.



If it's adjustable, it seems like there should be a way to do it with the Zenrom too. I never gave it a thought though, because my 41cx halfnut's display, from a normal usage angle, is really, really black against the silver-gray-- very easy to read in any light.


Yes and no. You can adjust the constrast with the Zenrom, if you also have an MDLD or similar device to store machine code in. The Zenrom will allow you to write m-code, but will not access peripherial devices itself.

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