Each SPARC based system has a PROM (programmable read-only memory) chip with a program called the monitor. The monitor controls the operation of the system before the kernel is available. When a system is turned on, the monitor runs a quick self-test procedure that checks things such as the hardware and memory on the system. If no errors are found, the system begins the automatic boot process.
Some older systems might require PROM upgrades before they will work with the Solaris system software. Contact your local service provider for more information.