A digital computer has a common bus system for 16 registers of 32 bits each. The bus is constructed with multiplexers. 1. How many selection inputs are there in each multiplexer?

Assuming that each multiplexer in the bus system is designed to select one of the 16 registers of 32 bits each, the number of selection inputs in each multiplexer would be 4. This is because 16 can be represented in binary as 10000, which has 4 digits. Each digit represents a selection input that can be either 0 or 1, indicating which of the 16 registers should be selected. Therefore, to select one of 16 registers using a multiplexer, we need 4 selection inputs.