Answer to Question #242119 in Electrical Engineering for Adnan

Question

A digital computer has a common bus system for 16 registers of 32 bits each. The bus is constructed with multiplexers. a. How many selection inputs are there in each multiplexer? b. What size of multiplexers are needed? c. How many multiplexers are there in the bus? d. Draw the block diagram for this computer common bus system design. 

Answer 1

Number of registers = 2ⁿ , where n= number of selection input lines

Here, number of registers = 16 = 2⁴

Therefore, n = 4

   Number of selection inputs in each multiplexer = 4

b) Size of multiplexer:

   Size of multiplexers = Number of registers X 1

    Here, Number of registers = 16

Therefore, Size of multiplexers = 16 X 1

c) Number of multiplexers in the bus:

   Number of multiplexers = Number of bits in each register

   Here, Number of bits in each register = 8

   Therefore, Number of multiplexers in the bus = 8

e) Advantages of multiplexer:

• Multiple circuits combinations can be implemented using multiplexer.
• It simplifies the logic design of the circuit.
• The circuit with multiplexers is less complex and the transmission cost is economical.
• No K-maps or simplification is needed in such logic designs.