Pip-Boy

“The RobCo Pip-Boy is the ultimate in personal computing devices.” — Fallout 4 loading screens
The Pip-Boy 3000 Mark IV is a pre-War Personal Information Processor (PIP) in Fallout 4 manufactured by RobCo Industries and acts as a database for the wearer's personal information and inventory. It is an updated version of the Pip-Boy 3000. Its operational manual can be read here.
Background The Pip-Boy 3000 Mark IV was distributed to all six Vault-Tec vaults in the vicinity of Boston: Vault 75, Vault 81, Vault 95, Vault 111, Vault 88 and Vault 114.