It did not have a built-in floppy disk drive and was noted for its unique compact design that placed a trackball pointing device in front of the keyboard for ease of use.

Apple's then-chief executive officer (CEO) John Sculley started the PowerBook project in 1990, allocating $1 million for marketing.

Despite the small marketing budget, the new PowerBook line was a success, generating over $1 billion in revenue for Apple in its first year.

[5] In 1991, the two leaders in the laptop computer industry were Toshiba and Compaq, both of which had introduced models weighing less than 8 lb (3.63 kg).

Advertising agency Chiat/Day filmed retired Los Angeles Lakers basketball star Kareem Abdul-Jabbar sitting uncomfortably in a small airline coach seat yet typing comfortably on his PowerBook.

Apple set a target of selling over 200,000 units of the PowerBook within the first year, with peak demand anticipated in the initial three months following its release.

[8] Apple soon solved the supply problems, and the proceeds from PowerBook sales reached $1 billion in the first year after launch.

Apple surpassed Toshiba and Compaq as the market leader in worldwide share of portable computer shipments.

Sales decreased, and by December 1991 the 140 and 170 models had become more popular because customers were willing to pay more for a built-in floppy disk drive and second serial port, which the PowerBook 100 lacked.

As a result, for the first time a user could not print directly and access AppleTalk or a faster external modem simultaneously,[19][20][21] and devices such as advanced MIDI interfaces could not be used because they required the dedicated use of both ports.

This provided a convenient method for software to be installed onto the PowerBook or transferred to the desktop, without the need for the 100's optional floppy disk drive.

[29] The 100's styling was based on those computers and represents the first improvements to the PowerBook line as Apple benefited from the lessons learned in developing the more powerful models' enclosure.

[30] Using a basic blueprint from Apple, including a list of chips and other components, and the Portable's architecture, the 100 was miniaturized and manufactured by Sony in San Diego, California, and Japan.

[31][32] Sony engineers had little experience building personal computers but nonetheless completed Apple's smallest and lightest machine in under 13 months,[30] cancelling other projects and giving the PowerBook 100 top priority.

[33] The trackball, another new design element, was placed in the middle of the computer, allowing the PowerBook to be easily operated by both left- and right-handed users.

[33] Crystal Waters of Home Office Computing praised the PowerBook 100's "unique, effective design" but was disappointed because the internal modem did not receive faxes, and the 100 had no monitor port.

[34] Waters concluded: "Having used the 100 constantly in the past few weeks, I know I wouldn't feel cheated by buying it - if only it had a 40MB hard-disk drive option.

[35] Byte magazine's review concluded, "The PowerBook 100 is recommended for word processing and communications tasks; the higher-end products offer enough power for complex reports, large spreadsheets and professional graphics.