Re: New owner of 41c seeks advice Message #9 Posted by Garth Wilson on 13 Sept 2012, 6:05 a.m., in response to message #8 by John Abbott (S. Africa)
41CL: http://systemyde.com/hp41/ , http://www.wiki4hp.com/doku.php?id=41cl:replacement_cpu_board
Yes, if you have a coconut 41c, which is likely, as opposed to the later halfnut, the 41CL would be the best. I don't go for it myself because I have a halfnut 41cx and I cannot get along without the time module portion of it, and separate time modules are nearly impossible to find.
The original HP-41's were internally code-named "Coconut" by HP. Later, in the summer of 1983, they planned to come out with a less-expensive version, partly by cutting the number of ports in half, hence the code name "Halfnut." They made it less expensive to produce and more reliable, but they ended up keeping all the ports, despite the company's internal code name for it. Halfnuts started shipping to dealers in approximately September of 1985. Today you can replace the original Coconut's logic printed circuit board with the 41CL board which is much, much faster and has ROM images for over 140 modules built in; but you cannot do that with the later Halfnut version. Since you have a 41c, not 41cv or 41cx, I suspect you have a coconut, not a halfnut, as the 41c was only provided in halfnut version for service replacements by the time the halfnut came out. Outside of that, 41's were all 41cv or 41cx by then. In spite of the jargon that flies around here, note that there never was one code-named "fullnut"!! No such thing. If you get the museum DVDs, you can read about the halfnut in the article "HALFNUT -- AN INTERNALLY IMPROVED HP-41C, CV, CX," by Richard Nelson and Jeremy Smith, in the CHHU Chronicle V2N4 (Jul/Aug 1985), pages 9 through 11.
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