“Cliff explains his passion for two Friden EC-132s.” These are transistor-based desktop calculators, with small CRT display showing a 4-deep operand stack, and using wire memory (torsion wave recirculating memory)
Cliff Stoll wrote “The Cuckoo’s Egg” which is very readable - a story of tracking down a hacker, starting from a tiny computer-time accounting discrepancy. There’s a profile of Cliff here: