The HP15C corner
The HP-15C is a high-end scientific pocket calculator with a root-solver and numerical integration. A member of Hewlett-Packard Voyager series of programmable calculators, it was produced between 1982 and 1989. The processor used the then new technology of Silicon on Sapphire that allowed ultra-low consumption. The 3 button batteries provided often lasted decades!
For many users, it is the pinnacle of HP calculator engineering together with the HP42s. Due to its popularity, and based on the then-new HP12c ARM-based platform, it was reintroduced in 2011 as HP15c Limited Edition. It was 150 times faster than the original, but it had higher consumption and the batteries would last around 4 months or normal use.
On May 2nd, 2023 HP announced the new HP15c Collector's Edition: the new version, with more speed, more memory and more battery life than the previous iteration.
