HP41 open source modules?

[Marcovecchio]

Thank you, Didier! I'll try to find the resources you pointed.

And thanks for the heads up, Bob! Your comment about the connector is very important, this is the kind of thing I have to know before starting any adventure like this.

When I say Diego's modules are expensive, I don't mean they're not worth the money. It's just that, in my case, I would like to improve a collection calculator and learn something in the process, while having fun with some soldering. It's much more about a DIY project, than about turning my HP41CV into a more powerful machine!