Reaching the portable computer intersection of uniting smallest effective size with highest reasonable usefulness has tortured personal computer makers for 30 years. Over the last decade, the functionality side of the equation has won out. As soon as portable PCs could match the full functionality of a bulky stationary model—becoming so-called “desktop replacements”—laptop sales started to take off. Barely 20 percent of all PC sales at the beginning of the decade, portable PCs—laptops, notebooks, netbooks, and everything in between—will likely represent 80 percent of such sales by the end of 2010.

What dynamized the laptop revolution, however, wasn’t compactness alone. The spread of WiFi hotspots made computing away from home easy, and prices sank low enough to put PCs within students’ budgets. Ironically, the most popular of the early computers were considered portable, although they were hardly that.

It Ain’t Heavy, It’s My PC

Throughout the 1980s, Osborne, Kaypro, Compaq, Commodore, and IBM all introduced popular “transportables,” essentially large briefcase-shaped PCs weighing from 23 to 30 pounds. The only portable alternatives to these hulks were such comparative toys as the Timex Sinclair and Radio Shack TRS-80 series. Hardly more than fancy calculators and word processors, these ur-PDAs were about the size of a paperback, powered by AA batteries, and cost less than $200.

The mid-1980s saw larger monochrome LCD screens become viable and affordable, replacing the bulky five- to nine-inch CRT monitors used in transportables. Components continued to shrink, hard disk drives became more copious, and, following Moore’s law, chip sets doubled in power every two years. Most important, rechargeable batteries grew more powerful.

One of the first commercially viable laptops was announced in 1985—the 12-pound Kaypro 2000, the first hinged-top, clamshell-styled portable, but it offered just a half-VGA (Video Graphics Array)-height 640 × 200 pixel monochrome LCD screen. Several evolutionary steps followed, but none nearly powerful or flexible enough to double as a desktop PC.

Compact Compaq

Compaq, which made its reputation with a series of excellent transportables, insisted that it wouldn’t produce a laptop until it could be as powerful and functional as a desktop PC. To its designers, led by Tom Mitchell, this meant a clamshell designed with a smaller footprint than contemporary pizza box–sized portables. It had to be small enough to fit on an airplane’s pull-down tray table, sport a full-sized VGA screen, come with plenty of shock protection against expected metaphorical and physical bumps in the road, and run completely on batteries.

After a year in development, Compaq introduced the SLT/286 on October 17, 1988. Beginning at $5,400 and weighing 14 pounds, the model had drawbacks, but it measured two to three inches smaller than previous laptops—the first true battery-powered laptop with a full VGA display. Almost simultaneously, NEC announced its UltraLite, a thinner MS-DOS “notebook”—which meant it was the size of a standard paper work pad—also with a full VGA screen but weighing just five pounds. A year later, Apple unveiled its first portable Macintosh, and the small-but-powerful race was on.

Throughout the 1990s, laptops began to rival desktops, boasting full color, higher-resolution screens, broadband and WiFi connectivity, and the ability to run Microsoft Windows. By 2005 the term “desktop replacement” had become popular to describe fully functional laptops with 16- to 17-inch screens, and the average price dropped below $1,000, less than that of many desktop PCs. Laptops were now virtually ubiquitous among students, and net connectivity via either WiFi or a USB cell modem was making them ever more flexible—and more valuable—than their house- or office-bound siblings.

But, as with the early transportables, some consumers found even the five-pound, 13-inch laptops too bulky to schlep around. To satisfy the lightest-packing PC users, Asus unveiled its Eee PC, the first so-called netbook portable PC, in 2007. Powered by Intel’s Atom processor and equipped with a 10-inch screen, the Asus and the subsequent Atom-powered netbooks are not as powerful as larger laptops, but are lighter—around three pounds or less—and cheaper by around half than their traditional brethren, attracting a flood of new users.

Future Trends:

Portable PCs now come with screens in nearly every size between 10 and 17 inches. While all laptops grow more powerful with longer-lasting batteries, the future of portable computing may not be in the familiar clamshell-screen laptop configuration. For instance, iPhone, Android, BlackBerry, and other open application smartphones are now considered powerful pocket computers. But tablet computers (flat clipboard-like portables whose large touchscreens have replaced keyboards), which combine multimedia, communication, e-book, and computing functions, are thought to be the next wave of portable computing. The age of tablet computing has been predicted for more than a decade, but the few all-screen models to have made it to store shelves have failed to catch on. What’s been lacking is a so-called killer app, a functionality to match its form factor, and input options, such as a capacitive touchscreen not requiring a stylus, true handwriting recognition, or speech-to-text capabilities to replace the qwerty keyboard.

Designers recognize that a tablet has to be something more than a PC with a touchscreen sans a physical keyboard. Hopes for a tablet breakthrough have been vested in Apple, which will reportedly introduce a revolutionary tablet dubbed iPad in the next few months. The iPad has been described as a giant iPhone but running an unknown operating system and possibly revolutionary functions including e-books and e-magazines. Apple’s reputation for innovation has ratcheted up expectations for tablet breakthrough. But the conundrum remains—what is the perfect screen size?

Bio:

George Heilmeier (1936—)

No single technology proved more critical for the success of the laptop computer than the liquid crystal display (LCD) screen, which in turn was almost impossible without George Heilmeier, who led the LCD development team at RCA’s David Sarnoff Research Center in the mid-1960s. In 1963 he and fellow RCA researcher Richard Williams published a paper proposing the use of liquid crystals for use in a display, after discovering how an applied voltage could change the color of a dye-doped nematic liquid crystal—a technology called dynamic scattering method (DSM). By 1968 DSM was perfected with an eye toward its use in flat TV screens, a dream of legendary RCA chairman David Sarnoff. Even though DSM was later surpassed by other technologies, Heilmeier, who owns 15 patents, is credited with the major contributions that led to LCD’s commercial use. Fittingly, Old Alumni Hall, the primary engineering department lecture building at his alma mater, the University of Pennsylvania, has been renamed Heilmeier Hall in his honor.

Stats:

2003 laptop computer sales: 7.3 million

2009 unit sales/household penetration: 21.5 million