How does a computer address ddr 4 sdram memory?
These address pins are used in a multiplexed fashion for row and column addresses. Extremely simplified, it means that accessing 4 GB (which needs 32 address bits) only 16 address bits are sent at a time in two parts. In reality it is slightly more complicated as there are X rows and Y columns and Z banks in a single chip and there are multiple chips per memory module which all add up to the total module size.