APL 5100

APL 5100 was the one of the two programming languages that ran on the IBM 5100. The 5100 was a portable (25 kg/55 lb) computer, released in the UK in 1976, and is regarded by some as the grandfather of the IBM PC. At the time of its release, the smallest model cost about £9000, then the price of a London apartment.

The IBM 5100 was available with 16K, 32K, 48K and 64K bytes memory sizes, and a 16K machine had an available workspace size of just over 9K bytes. It used a proprietary 16-bit processor called PALM which could run emulators for the System/360 and System/3, and could run APL and/or BASIC, depending on the model. The code for the APL and BASIC interpreters was stored in ROM, referred to as ROS (Read Only Storage) in the Maintenance Manuals. The APL interpreter was based on System/360's APL.SV.