In computer architecture, 64-bit computing is the use of processors that have datapath widths, integer size, and memory addresses of 64 bits (8 octets) wide. Also, 64-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. From the software perspective, 64-bit computing means the use of code with 64-bit virtual memory addresses. A 64-bit register can store 264 (over 18 quintillion) different values. Hence, a processor with 64-bit memory addresses can directly access 264 bytes of byte-addressable memory.