Subnotebook

To the extent that it still exists, 'subnotebook' could be defined as machines with screen smaller than 13" but with a permanently-attached keyboard intended for two-handed typing.

[8][9] The similarly designed TRS-80 Model 100 from 1983 was the first commercially successful notebook and is credited with spawning an industry of smaller portable computers.

[10][11] Like the HX-20, the Model 100 was smaller than contemporary clam-shell machines; both use a slate form factor, with no hinge and the keyboard and screen on the same plane.

The NEC UltraLite, launched in 1988, was the first clamshell "notebook computer" compatible with the IBM PC, a platform whose market share dominated the microcomputer industry throughout the 1980s onward.

Its relatively small dimensions — 48 × 220 × 280 mm (1.4 × 8.3 × 11.75 inches) — matched those of a pair of stacked US Letter (similar to A4) size paper notebooks.

[11] Owing to its lack of a floppy drive (in favor of proprietary solid-state storage), the UltraLite did not see massive uptake by the general public.

[12][13] The success of the LTE convinced IBM and Apple to release their own slimmer laptops, starting with the PS/2 Model L40 SX and the PowerBook 100, respectively.

At the end of 1992, PCMag magazine[17] described two models as subnotebooks: these were the Gateway HandBook the Dell 320SLi[18][19] (both less than a 1.6 kg weight), and another was released in Italy: the Olivetti Quaderno.

Another early model was the Hewlett-Packard OmniBook 300, which was launched as a "superportable" in 1993; it was one of the first examples to use a flash memory disk instead of a hard drive, to reduce the weight.

In 2000 Compaq released a more compact successor of Digital HiNote line - the 10.3" Armada M300, with magnesium case and 1.6 kg weight.

On the other hand, over the course of the 2010s, with growing of sales for mainstream users, optical drives and legacy ports became uncommon, and some classic subnotebook features (like additional replaceable batteries, alternative input methods, docking options, Smart Cards, mobile broadband modules, additional storage) become rare.

Noticeable releases: In 2007 the ASUS Eee PC became the first of a new class of low-cost laptops commonly called netbooks.

Over the next several years, specific marketing of laptops as "subnotebooks" died out, and since 2017 the term is essentially dead in mainstream branding.