1 Consider the control unit and microinstruction format shown in the figure belo
ID: 3594338 • Letter: 1
Question
1 Consider the control unit and microinstruction format shown in the figure below. Assume that the control memory has 2048 words of 32 bits each. Assume that the system has 15 status bits and that 15 bits are used to specify the micropoerations. a. What is the size of the "branch address" field of the microinstruction? b. How many bits are there in each of the mutiplexer input lines (the lines shown in blue)? c. As part of the "branch selection" field, how many bits of the microinstruction are needed for selecting a status bit? As part of the "branch selection" field, how many bits are needed as selection bits for the shown multiplexer? In fact, the shown multiplexer represents many multiplexers. How many such multiplexers are there and how many input lines are there for each multiplexer? How many bits are there in the control address register? How many bits are there in the control data register? d. e. f. g. Instruction code StatusBranch Multiplexer bits select ter Control address register Control memory (ROM) Microinstruction Control Data register Branch Branch elect a status bit Microoperations Branch addressExplanation / Answer
a)
b) 4 MULTIPLEXER LINES
c) SEVEN BITS ARE NEEDED
d)FOUR BITS ARE SELECTED
e)TWO INPUT LINES
f)TWO BITS PER LOCATION
g)we have 8 bits for every location, therefore your memory needs a data bus with 8 lines. Every time you read a location (by loading its address on the address bus), the 8 bits that are stored at that location are loaded (by the memory chip) on the 8-line data bus.
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