The are two major support &architecture; flavors: PA-RISC 1.1 and PA-RISC 2.0. The PA-RISC 1.1 architecture is targeted at 32-bit processors whereas the 2.0 architecture is targeted to the 64-bit processors. Some systems are able to run either kernel. In both cases, the userland is 32-bit. There is the possibility of a 64-bit userland in the future.