GATE | Gate IT 2008 | Question 37

Consider a CPU where all the instructions require 7 clock cycles to complete execution. There are 140 instructions in the instruction set. It is found that 125 control signals are needed to be generated by the control unit. While designing the horizontal microprogrammed control unit, single address field format is used for branch control logic. What is the minimum size of the control word and control address register?
(A) 125, 7
(B) 125, 10
(C) 135, 7
(D) 135, 10


Answer: (D)

Explanation: As each instruction akes 7 cycles
=> 140 instructions will take = 14*7 cycles
=> 2^m>=980
=>m>=10
=> 10+125 bits and 10 bits

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