HP-41CX CPU broad install to HP-41C

[zixingcheche]

Hi all
Same as title, can I change the 41C’s CPU broad with 41CX’s CPU broad?

I have working 41c & 41cx, but enter key of 41cx has some issue.
I want to install the 41CX’s cpu into 41c.

Any issues? Risk?
Thanks!
Thanks!

[ThomasF]

Hi,

No, that is not possible, since the 41CX has a totally different internal design.

See e.g. the pictures here of the internals of the 41C and 41CX: HP41C Museum

The C and CV had a separate board for the CPU and memory, but CX used both components on the keyboard PCB and a totally different board.

Switching between C and CV is normally no problem, but the CX is a different beast ...

Cheers,
Thomas

[Harald]

(02-13-2023 07:49 AM)ThomasF Wrote:  The C and CV had a separate board for the CPU and memory, but CX used both components on the keyboard PCB and a totally different board.

That depends. If the CX is a Halfnut, that is true, but if it is a Fullnut, then the boards can be interchanged. There might be a display driver incompatibility in some cases, but I can't remember. Maybe someone with more knowlage on the 41 can enlighten us.
You can tell if the CX is a Fullnut or a Halfnut by looking at the display. The Halfnut has rounded display corners.

Cheers,
Harald

[ThomasF]

(02-13-2023 09:15 AM)Harald Wrote:  

(02-13-2023 07:49 AM)ThomasF Wrote:  The C and CV had a separate board for the CPU and memory, but CX used both components on the keyboard PCB and a totally different board.

That depends. If the CX is a Halfnut, that is true, but if it is a Fullnut, then the boards can be interchanged.

Thanks Harald!

Yes, that it true - I was just thinking of the Halfnut CX, but there also exists Fullnut CX, and then it might work!
Have swapped a lot of C and CV boards, but never had a CX board to swap ...

Cheers,
Thomas

[zixingcheche]

Hi Thomas, Harald,

Thank you for your reply!
My 41cx is halfnut, and 41c is fullnut.
So, the cpu broad can not be exchanged.

Understand, thanks!

BR,
Bai