You can obtain the PROM revision level, hardware platform, RAM installed, serial number, Ethernet address, logo, and the host id by using the following command in the Open Boot Prom (OBP) mode: banner. The firmware information can be very useful, especially if you are upgrading processors. I used it to determine if a firmware update was required for new processors--That was the case.
Here's an example.
Note: If you looking for the UNIX banner command, which outputs string information, here’s its post: Using UNIX banner to print to STDOUT