CASIO CD-813 memory-8A


Brand: CASIO
Model: CD-813 memory-8A
Type: Calculator
Picture: CASIO CD-813 memory-8A
Batteries: AA x 2
Lifetime: Introduced: 1974
Terminated: 1976
Notes: Nice plain calculator with memory, square roots, percentages and the ability to set the display to two-decimal currency mode, either truncated ("CUT") or rounded ("5/4").

There’s no display indicator to show that a non-zero number is stored in its memory. The "AC"-key clears the memory.

When the calculator is performing operations, its display shows all kinds of intermediate results which looks quite cool actually. This is especially visible whilst calculating square roots. Talking about those, the calculator thinks √-9 = -3 which is very uncommon for calculators newer than the early 1970’s.

Talking about zeroes: this calculator has negative zeroes. When you calculate "2" "÷" "3" "×" "3" "-" "2" "=" the display will show "-0".


A power adapter, the CASIO AD-2S. Although I found this one with a Vendomatic CASIO 3C 860.96.05.150 adapter. Vendomatic was a brandname of the Dutch retailer V&D (Vroom & Dreesman), now defunct.