Our detapath is so simple that in some cases we could get therid of one of ten c

ID: 3617288 • Letter: O

Question

Our detapath is so simple that in some cases we could get therid of one of ten control signals and use another signals in itsplace some or all the instructions would still work correctlyconsider each of the following substitution In each case answerfollowing question would all four kinds of instructions still work?if not which ones fail? substutute ALUSrc for memToReg substitute MemRead for MemToReg aubstitute ALUSrc for memRead Our detapath is so simple that in some cases we could get therid of one of ten control signals and use another signals in itsplace some or all the instructions would still work correctlyconsider each of the following substitution In each case answerfollowing question would all four kinds of instructions still work?if not which ones fail? substutute ALUSrc for memToReg substitute MemRead for MemToReg aubstitute ALUSrc for memRead

Explanation / Answer

From the following table showing the values of control lines wecan say which instructions will work even after substituting onesignal with another.

Instruction

RegDst

op1

op0

ALUSrc

Branch

Mem-Read

Mem-Write

Reg-Write

Memto-Reg

R-format

beq

Substitute ALUSrc for MemToReg:

When MemToReg is substituted with ALUSrc, the instructions thatneed the MemToReg signal will not work correctly. From the abovetable we can know that lw instruction depends on MemToReg signal.Hence it will not work correctly and all the remaining threeinstruction groups work as usual.

Substitute MemRead for MemToReg

When MemToReg is substituted with MemRead, the instructions thatneed the MemToReg signal will not work correctly. From the abovetable we can know that lw instruction depends on MemToReg signal.Hence it will not work correctly and all the remaining threeinstruction groups work as usual.

Substitute ALUSrc for memRead

When MemRead is substituted with ALUSrc, the instructions thatneed the MemRead signal will not work correctly. From the abovetable we can know that lw instruction depends on MemRead signal.Hence it will not work correctly and all the remaining threeinstruction groups work as usual.