“This is an HP-41C pocket calculator, manufactured by Hewlett-Packard, that has flown on nine Space Shuttle missions in the 1980s. NASA purchased it from a local store in Houston, and installed special software on it for each mission. Mission critical computing was still done by the Shuttle on-board computers, but pocket” calculators found many other uses in space. This calculator could have performed critical re-entry calculations if the main computers failed. This HP-41C was used by Astronaut Sally Ride and several other astronauts on a total of nine Shuttle missions.” source https://airandspace.si.edu/collection-objects/calculator-hand-held-hp-41/nasm_A19890003000