prtconf | head
Example output:
~ # prtconf | head System Model: IBM,9131-52A Machine Serial Number: 181DF2G Processor Type: PowerPC_POWER5 Number Of Processors: 4 Processor Clock Speed: 1499 MHz CPU Type: 64-bit Kernel Type: 64-bit LPAR Info: 1 10-0DE5G Memory Size: 7904 MB Good Memory Size: 7904 MB