Building a keyboard for a 1985 Casio FX-451 calculator (part 1/2)

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 first 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 two:    • Building a keyboard for a 1985 Casio FX-45...   Did I mention the calculator was already broken? It was. 0:00 Introduction 3:47 Begin disassembly 4:35 Hey, look, a chip 7:10 Continued disassembly 9:55 Destructive disassembly 19:33 Analysis 27:53 Even more destructive disassembly 31:35 A new contender appears! 40:57 The new contender falls flat on its face 44:41 Starting again 52:01 Soldering problems 55:16 Does it work yet? 58:27 PREVIEW OF PART 2