To learn how addressing modes work for load and store instructions on PowerPC processors, you must first understand a little bit about the PowerPC instruction format.

The PowerPC uses a load/store (also called RISC) instruction set, which means that the only time it accesses main memory is for loading into registers or copying a register to memory.

Note that test1 must load and store the global errs value each time it is incremented, whereas test2 stores localerrs in a register and needs only a single instruction.