I enjoy learning about the history of mechanical and electronic calculators, and I've written a few articles in this field.  I'll be happy to post in this site any related articles that you may want to write.  You will find here several resources that may be useful if you collect old calculators

I'd also like to invite you to review my Patent No. 5,623,433 for "Extended Numerical Keyboards with Structured Data-Entry Capability." This method improves the traditional 10-key numerical keyboard by introducing 3 additional keys which allow to enter a number in the same way as you think on the number, rather than as a cold sequence of digits.