The HP-11C (which I bought ~ 30 years ago to replace a HP-15C that took one too many drops) is still going strong on the ORIGINAL battery from the factory. I m

The HP-11C (which I bought ~ 30 years ago to replace a HP-15C that took one too many drops) is still going strong on the ORIGINAL battery from the factory. I marvel frequently that while CPUs, storage, and displays are unphantomly better, the physical design and feel of the keys on the 30+ year old calculator is still unsurpassed.