A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator. In contrast, the batch processing or time-sharing models allowed larger, more expensive minicomputer and mainframe systems to be used by many people, usually at the same time. Large data processing systems require a full-time staff to operate efficiently.
Software applications for personal computers include, but are not limited to, word processing, spreadsheets, databases, Web browsers and e-mail clients, digital media playback, games, and myriad personal productivity and special-purpose software applications. Modern personal computers often have connections to the Internet, allowing access to the World Wide Web and a wide range of other resources. Personal computers may be connected to a local area network (LAN), either by a cable or a wireless connection. A personal computer may be a desktop computer or a laptop, tablet, or a handheld PC.
The Macintosh Portable was Apple Inc.'s first attempt at making a battery-powered portable Macintosh personal computer that held the power of a desktop Macintosh. It was also the first commercial off-the-shelf portable computer used in space and the first to send an email from space, in 1991 aboard Space Shuttle mission STS-43.
Released on September 20, 1989, it was received with excitement from most critics but with very poor sales to consumers. It featured a black and white active-matrix LCD screen in a hinged cover that covered the keyboard when the machine was not in use. The mouse function was handled by a built-in trackball that could be removed and located on either side of the keyboard. It used expensive SRAM in an effort to maximize battery life and to provide an "instant on" low power sleep mode.