Q4Microprocessor and Microcontroller

The lower 8 bits of the Address Bus ($A_0-A_7$) and the 8 bits of the Data Bus ($D_0-D_7$) are physically multiplexed onto the exact same set of 8 physical pins ($A{D}_0-A{D}_7$). This multiplexing is a highly calculated engineering compromise designed to drastically reduce the total pin count of the 8085 IC to exactly 40 pins, lowering manufacturing costs and shrinking the footprint.