I have the main unit.
type handeld computer
country Japan
year 1995
graphic LCD
colors mono
The Casio DC-850 — Data Bank Calculator
The Casio DC-850 was a data bank calculator combining arithmetic with personal information storage — part of Casio’s pioneering range of combined calculation and organiser devices. Casio essentially invented the electronic organiser category in the early 1980s, creating products that stored phone numbers, addresses, and notes alongside calculation functions. The DC-850 represented this convergence: a practical everyday device that eliminated the need to carry both a calculator and an address book separately.