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Joined: Aug 2005
Hi;
the keyboard PCB and the LCD module for the halfnut (newer) and the fullnut (earlier) are different from each other. I have both types: HP41CV full- and halfnut. There is no way to use the main PCB of a fullnut with the inner circuitry of a halfnut. The halfnut LCD module contains ROM and RAM, while the uP is in the keyboard. All of these are in the main PCB of the fulnut.
Hope this clarifies.
Cheers.
Posts: 1,162
Threads: 26
Joined: Aug 2005
The Fullnuts have a separate CPU/logic board. The keyboard PCB in a Fullnut is just the keyswitches, and the display driver hybrid is soldered to one edge of this PCB. The display driver hybrid is just the display driver. The CPU board contains the CPU chip, ROM, RAM, PSU chip, timer chip (in a CX), and so on.
The halfnuts have everything on one PCB. The CPU is a surface-mount decive solderd to the back of te PCB, under the keybaord. The display driver hybrid now also contains the ROM, RAM and PSU circuits.
Halfnut CXs have a little hybrid PCB mounted across the back of the main PCB, over the CPU. It cotnains the extra ROM, exteded RAM, and timer circuits. Alas, the ROM code in the dispay driver is different between the CV and CX, so you can't upgrade a CV just by adding the extra PCB.
AFAIK, no fullnut was ever converted into a halfnut by HP. To do that you'd have to replace the entire top case (including the PCBs). Just about all that's common between the fullnut and halfnut models is the bottom case and I/O assembly (the flexible PCB that connects to the modules and the battery pack.