41C Halfnut Character Set


I read CHHU Chronicle July/August 1985 pages 9-11i.
There is an article about the Halfnut improved HP-41C, CV and CX and it gives an extended character set with all of the lower case characters a-z.

My HP-41CX Halfnut and its manual does not show this extended character set. Does anyone know anything about it? Is it real? If it is real how can I display the characters? I have tried XTOA and this matches page 310 of the 41CX manual. The article refers to the A, B, and C registers with the extended character set, can anyone explain these?




The extra characters _do_ exist (as does the contrast control function), but you can't access them from Focal using any HP function, including Synthetic Programming (so XTOA won't work).
The only way to get them is by using Mcode (the HP41's machine code), which means you need a RAM box (such as an MLDL) and something like the MLDL-OS ROM or ZenROM.


I would love to get more information on this. I would like to try it out with CCD, ZENROM and HEPAX modules. I had only heard about the contrast. This function was included in the CCD Module.


where did you get that information from? i checked cat2 of the ccd module (it's a w&w ccd A), but i could not find any related function. or, is it a hidden goodie in the function block headers of the ccd's cat2??
(hm... forgot how to activate that. does anybody know how ?)

cheers, hans


I was mistaken ... It is provided in the HEPAX Module by VM Electronics. The function name is CTRAST. The manual on page 78 says:

"The CTRAST (display ConTRAST, HEPAX 005) function sets display contrast on the newer HP-41s (the Halfnuts, known by a black rim on the display). Place a number from 0 to 15 in the X register to set the contrast. 5 is default. This function has no effect on older calculators."

I am sorry about the error.

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