The following code is to run on a pipelined processor with one branch delay slot
$$\eqalign{ & {{\rm I}_1}:\,\,ADD\,\,{R_2}\,\, \leftarrow \,\,{R_7} + {R_8} \cr & {{\rm I}_2}:\,\,SUB\,\,\,{R_4}\,\, \leftarrow \,\,{R_5} - {R_6} \cr & {{\rm I}_3}:\,\,ADD\,\,{R_1}\,\, \leftarrow \,\,{R_2} + {R_3} \cr & {{\rm I}_4}:\,\,STORE\,\,Memory\,\,\left[ {{R_4}} \right]\,\, \leftarrow \,\,{R_1} \cr & BRANCH\,\,to\,\,Label\,\,if\,\,{R_1} = = 0 \cr} $$

Which of the instructions $${{\rm I}_1},\,{{\rm I}_2},\,{{\rm I}_3}$$ or $${{\rm I}_4}$$ can legitimately occupy the delay slot without any other program modification?

Consider a pipelined processor with the following four stages
$$\,\,\,\,\,$$$$IF:$$ Instruction Fetch
$$\,\,\,\,\,$$$$ID:$$ Instruction Decode and Operand Fetch
$$\,\,\,\,\,$$$$EX:$$ Execute
$$\,\,\,\,\,$$$$WB:$$ Write Back

The $$IF, ID$$ and $$WB$$ stages take one clock cycle each to complete the operation. The number of clock cycles for the $$EX$$ stage depends on the instruction. The $$ADD$$ and $$SUB$$ instructions need $$1$$ clock cycle and the $$MUL$$ instruction needs $$3$$ clock cycles in the $$EX$$ stage. Operand forwarding is used in the pipelined processor. What is the number of clock cycles taken to complete the following sequence of instructions?

A CPU has five stages pipeline and runs at $$1$$ $$GHz$$ frequency. Instruction fetch happens in the first stage of the pipeline. A conditional branch instruction computes the target address and evaluates the condition in the third stage of the pipeline. The processor stops fetching new instruction following a conditional branch until the branch outcome is known. A program executes $${10^9}$$ instructions out of which $$20$$% are conditional branches. If each instruction takes one cycle to complete on average, then total execution time of the program is

A $$5$$ stage pipelined $$CPU$$ has the following sequence of stages $$IF$$-Instruction fetch from instruction memory, $$RD$$-Instruction decode and register read, $$EX$$-Execute: $$ALU$$ operation for data and address computation, $$MA$$-Data memory access-for write access the register read and $$RD$$ stage it used, $$WB$$-Register write back.

Consider the following sequence of instructions:
$$\eqalign{ & {{\rm I}_1}:L\,R0,\,\,Loc1;\,R0 < \,\, = M\,[Loc1] \cr & {{\rm I}_2}:A\,R0,\,R0;\,\,\,\,\,\,R0 < \,\, = R0 + R0 \cr & {{\rm I}_3}:A\,R2,\,R0;\,\,\,\,\,\,R2 < \,\, = R2 - R0 \cr} $$

Let each stage takes one clock cycle.
What is the number of clock cycles taken to complete the above sequence of instructions starting from the fetch of $${{\rm I}_1}?$$