A computer addressing mode and memory access method rely on a memory segment identifier and a memory segment mask for indicating memory locations. In this addressing mode, a processor receives an instruction comprising the memory segment identifier and memory segment mask. The processor employs a two-level address decoding scheme to access individual memory locations. Under this decoding scheme, the processor decodes the memory segment identifier to select a particular memory segment. Each memory segment includes a predefined number of memory locations. The processor selects memory locations within the memory segment based on mask bits set in the memory segment mask. The disclosed addressing mode is advantageous because it allows non-consecutive memory locations to be efficiently accessed.