There are essentially three classes of portables: laptops, notebooks and palmtops.
Laptops are of the size of a small, slim attache case and weigh around 7 to 12 kg. They offer the same power as a desktop machine. These are essentially scaled down desktops, and use a reduced keyboard and mouse as input devices. The disadvantage of a laptop is that it is bulky. It is also very difficult to operate a mouse without a desk. Examples of laptops are Toshiba 5200C from Toshiba and SLT/286 from Compaq Computer Corporation.
Laptop
Notebooks have been designed to overcome the disadvantages of a laptop. Notebook computers are about the size of a notebook (approximately 21 x 29.7 cm.) and weigh about 3 to 4 kg. Notebooks also offer the same power as a desktop PC. Examples of notebooks are Contura 3/20 from Compaq, and AcerAnyWare from Zenith Computers Ltd.
Notebook
Palmtops are the smallest of portables and are normally the size of a pocket calculator. These, however, do not offer the same power as that of a PC. The applications are limited and built-in, for example, Hewlett Packard's HP95LX comes configured with LOTUS 1-2-3, a spreadsheet. They are useful for data entry operations in the field.
Palmtop