The Quaderno was a subnotebook produced by Olivetti in two versions from 1992: Quaderno (PT-XT-20) and Quaderno 33 (PT-AT-60).
Quaderno PT-XT-20
Olivetti Quaderno PT-XT-20, side photo
Olivetti Quaderno 20 and Olivetti Quaderno 33 – RetroComputer museum Zatec, Czechia
Olivetti Quaderno 33 (PT-AT-60) – RetroComputer museum Zatec, Czechia
Subnotebook, also called ultraportable, superportable, or mini notebook, was a marketing term for laptop computers that are smaller and lighter than a typical notebook-sized laptop.
Sizes (smallest to largest): Nintendo DS Lite (handheld), Asus Eee PC (netbook) and 13.3" MacBook (laptop).
Sizes of classic subnotebooks (2001's ThinkPad s30, 10.4") and early netbooks (2008's Eee PC 901, 8.9"); note to reduced keycaps size
An Apple PowerBook Duo 270c
11.6" 2012's Samsung Series 3 Chromebook