I have the main unit.
Type Pocket computer
The Casio PB-100 — Pocket BASIC Computer
The Casio PB-100, released in 1981, was one of the earliest genuinely pocket-sized BASIC computers — small enough for a shirt pocket yet capable of running programs of up to 544 steps. At an accessible price point, the PB-100 introduced programming to students who could not afford larger home computers, and its optional FA-3 thermal printer made it practical for scientific calculations requiring documented output. The PB-100’s combination of size, capability, and price made it one of Casio’s most successful early computing products, sold worldwide through electronics retailers and educational channels throughout the early 1980s.