The IBM 5100 series computers were aimed for small to medium business and for those without or only small knowledge of computers but who wanted to use their benefits. In 1975 the IBM 5100 was announced as "Portable Personal Computer". Then follows the IBM 5110 in 1978 and the IBM 5120 in 1980.

The IBM 5110 was offered as two models and different accessories and options:

The IBM 5110 Model 3 is not a separate computer but the base of the IBM 5120, the version with built in diskette drives and bigger screen.

The computers were equipped with different options. The base configuration was 16 kB of main storage and no external devices, other options offered 32kB, 48kB or 64kB of main storage. For external peripherals the I/O bus connector can be used to attach devices like disk drives and a printer. Up two two internal devices for communications were available.
All the machines could be ordered with APL, BASIC or both as programming language (built into read-only storage). In the last case, the desired language can be selected with a switch on the front panel; it is available after a restart.

The diagnostic control program (DCP):
(captured from the video output connector)