- OBP (OpenBoot PROM)
The hardware-level user interface that you see before the operating system starts. The OpenBoot PROM consists of two 8KB chips on the system board: the startup PROM itself, which contains extensive firmware allowing access to user-written startup drivers and extended diagnostics, and an NVRAM (nonvolatile random-access memory) chip.
The primary task of the OpenBoot firmware is to boot the operating system either from a mass storage device or from the network. See also OBP.