Boot PROM Firmware (OpenBoot)
A system's boot Programmable Read-Only Memory (PROM) stores the firmware that is executed immediately after the system hardware finishes the Power On Self Test (POST). This firmware, called OpenBoot, is the standard firmware for Sun systems. OpenBoot firmware pertains only to SPARC platforms, but some limited comparable functionality is available on Intel x86 platforms as well.
OpenBoot is used to boot the operating system, run diagnostics, modify boot-related parameters stored in nonvolatile RAM (NVRAM), and provide a Forth interpreter used to execute the Forth Monitor.
Currently, two supported versions of OpenBoot are available: version 2.x and version 3.x. OpenBoot 2.x was introduced with SPARCstation 2 and SPARCstation ...