An internal channel from the
CPU (Central Processing
memory across which the addresses of data (not the data) are transmitted. The
number of lines (wires) in the address bus determines the amount of memory that
can be directly addressed as each line carries one bit of the address.
example, a 20-line address bus represents the binary number 1,048,576 and
reaches that number of memory bytes (the size of the address bus in the
IBM PC in 1981). A computer with a 32-bit address bus can directly address
4GB of physical memory, while one with 36 bits can address 64GB.