I purchased this calculator kit because I love vintage RPN HP calcs, and I didn't have any flavour of an HP-41, which was one of the few I didn't really know how to use.

So I was expecting having fun building it and getting some nice toy i could play with and learn about, but I wasn't expecting a really fully usable and fine machine that could compete with my daily use calculator.

And wow !

First, the kit arrived in 3 days from Mexico to France, excellent.

Second, I was truly impressed by the care and quality of the kit package, every little component in its small bag with a label, everything carefully packed.
Complete with the PC communications USB cable.
Then I saw the top-notch quality of the PCB and front and back planes, so good looking.
Then I built it, and this was quite a picnic.
The only thing is that the bolts and little brass stands are very small so take care not to lose one, because there is not a single spare one !

When building it, take care not to solder any part on the wrong side of the PCB, I did for a switch, then I cried, and also take care of cutting every component lead very short, as the space between the PCB and backplane will be very narrow, and you don't want to have short circuits there.

Then it was fully assembled and : WOW !

That's not a toy, that's an extremely good looking, fine, fully usable HP-41CX clone, far better than the original !

The display is excellent, extremely readable and crisp, the keyboard is very fine, responsive, highly usable.
My only regret is that the [Enter] key could not be made double-size - which is understandable - but at least I would have liked it with a specific colour.
(Note that there is one spare keyboard switch and black cap in the kit, so I could have made it black, and still could if I cared to disassemble it a bit.)

Now for the firmware : That's an accurate revival of the HP-41CX, only with a much better display that can display all the stack registers together, have more customization options, a status bar with a clock, a host of menus with internal display (registers, flags...) and USB link so you can backup and restore the calculator's memory to/from the computer.

And the PX-41CX includes a builtin copy of most of the most useful original HP-41 ROM modules : Advantage pack, Maths, Stats, Finance, Zenrom, Circuits, everything is already there, you only need to activate them from the menus, no need to go looking for ROM files on the web !

This is more than excellent, this is truly amazing !

So I end up with a top-notch, good looking, extremely usable HP-41CX clone that beats the original in every aspect.

And well I'm learning to get the best of it and it has immediately become my favorite, daily use, calculator.

Also I had the chance to exchange a few mails with Alex, who is extremely kind, helpflul and responsive, I'm happy to be able to exchange with the author of such a wonderful device and tell him how happy I am !

The only thing is that you will need to be a bit of a geek if you want to be able to customize the firmware and exchange data with your computer, this part is a bit documented here and there, still that's some geeky stuff, so if you are not easy with installing libraries from github and using command-line utilities, you might have a hard time there, but you don't need this to be able to use the machine.

So well, I'm the happiest buyer of a kit from which I didn't expect that much and ends up becoming the best calculator I ever owned.

Thanks Alex for this amazing product.