[a] The term notebook was coined to describe slab-like portable computers that had a letter-paper footprint, such as Epson's HX-20 and Tandy's TRS-80 Model 100 of the early 1980s.
In 1988, NEC's UltraLite defined a new category of notebook: it achieved IBM PC compatibility, making it technically as versatile as the largest laptops, while occupying a letter-paper footprint in a clamshell case.
[10] By this point, however, laptops were gaining hardware features faster than the industry could miniaturize their parts, leading to very heavy laptops—some upwards of 20 pounds (9.1 kg).
[17] In direct response to Compaq,[18]: 59 [19]: 75 both Apple and IBM, top players in the computer industry, made their hotly anticipated entries in the notebook market in 1991 and 1992, respectively, with the PowerBook and the PS/2 Note (a predecessor to the ThinkPad).
[22][23] Laptops and notebooks continued to occupy discrete market segments into the mid-1990s, with unit sales tracked separately by research firms such as Dataquest.
[37] Starting in 1997, screen sizes in notebook computers began increasing rapidly, fueled by consumer preference toward larger displays over compactness.
[41] Ergonomic considerations, as well the integration of pointing devices such as touchpads, also necessitated increasing the size of laptops to accommodate a larger palm rest area.