"The IBM 5100 Portable Computer, introduced on September 10, 1975, was one of the earliest attempts to shrink mainframe-style power into a transportable system. Evolving from the 1973 SCAMP prototype—built at IBM’s Los Gatos Scientific Center—the 5100 brought APL and BASIC computing to a single-user machine that weighed 25 kg and cost between $8,975 and $19,975. Although marketed as “portable,” it required mains power, yet its integrated design was groundbreaking: a 5-inch CRT, keyboard, tape drive, system ROM, and up to 64 KB of RAM housed in a suitcase-sized enclosure.

At its core was IBM’s 16-bit PALM processor, capable of addressing 64 KB directly and using bank switching for larger configurations. The machine’s ROM contained full interpreters for APL and BASIC—adapted from IBM’s System/370 and System/3 environments—enabled by microcode emulation. This allowed the 5100 to run software from larger IBM systems without redesign.

The 5100 offered QIC tape storage, optional external printers or typewriters, and a communications adapter emulating an IBM 2741 terminal. Users could connect an external monitor via BNC, and models supporting both languages included a hardware toggle to switch between APL and BASIC.

Withdrawn in 1982 after the release of the IBM 5110 and 5120, the IBM 5100 remains a pioneering milestone, representing IBM’s first practical step toward personal computing through portability and microcode-based compatibility."