address bus

The electronic channel, usually from 20 to 64 lines wide, used to transmit the signals that specify locations in memory.

The number of lines in the address bus determines the number of memory locations that the processor can access, because each line carries one bit of the address. A 20-line address bus (used in early Intel 8086/8088 processors) can access 1MB of memory, a 24-line address bus can access 16MB, and a 32-line address bus can access more than 4GB. A 64-line address bus (used in the DEC Alpha APX) can access 16EB.