Building a keyboard for a 1985 Casio FX-451 calculator (part 2/2)

In whch yr hmbl svt complete wrecks an already broken 40-year-old calculator in an attempt to turn it into another 40-year old calculator. This is the second half of a painfully long project where I disassemble, do some basic reverse engineering, and then rebuild an old broken calculator into a desk calculator, suitable for calculating on a desk. This involved an above-average amount of clumsiness, mistakes and other general incompetence. Enjoy. Part one:    • Building a keyboard for a 1985 Casio FX-45...   Did I mention the calculator was already broken? It was. 0:00 RECAP OF PART ONE 0:49 PCB wiring 5:08 Antepenultimate assembly 7:41 PCB wiring again 11:08 Mistakes in the PCB and you 20:08 That's not right 23:42 Papercraft 25:16 Power corrupts... 29:17 That's still not right 48:25 ...but we all need electricity 54:44 The big demo! 01:14:21 Project wrapup