Editing Bus (computing) (section)

=== Address multiplexing ===
Early processors used a wire for each bit of the address width. For example, a 16-bit address bus had 16 physical wires making up the bus. As the buses became wider and lengthier, this approach became expensive in terms of the number of chip pins and board traces. Beginning with the [[Mostek]] 4096 [[DRAM]], address multiplexing implemented with [[multiplexer]]s became common. In a multiplexed address scheme, the address is sent in two equal parts on alternate bus cycles. This halves the number of address bus signals required to connect to the memory. For example, a 32-bit address bus can be implemented by using 16 lines and sending the first half of the memory address, immediately followed by the second half memory address.

Typically two additional pins in the control bus{{snd}}row-address strobe (RAS) and column-address strobe (CAS){{snd}}are used to tell the DRAM whether the address bus is currently sending the first half of the memory address or the second half.