Explain why AD0-AD7 are multiplexed and A8 to a15 are not multiplexed?

AD0-AD7 are multiplexed because they serve dual purposes as both address and data lines, allowing for a reduction in the number of physical pins required on a microprocessor. This multiplexing is typically utilized for lower-order addresses that change frequently during data transfers. In contrast, A8 to A15 are not multiplexed because they are dedicated to addressing higher memory locations, which do not require frequent changes during data operations, allowing them to remain stable and independent. This distinction enhances overall efficiency in the design of the system.