GATE Computer Science (CS) 2020 Solved Papers

Given steps:
1. ${\mathit{R}}_{2\mathit{r}},{\mathrm{TEMP}}_{\mathit{r}}^1,{\mathrm{ALU}}_{\mathrm{add}},{\mathrm{TEMP}}_{\mathit{w}}^2$
2. ${\mathit{R}}_{1\mathit{r}},\mathit{T}\mathit{E}\mathit{M}{\mathit{P}}^1\mathit{w}$
3. ${\mathit{P}\mathit{C}}_{\mathit{r}},{\mathit{M}\mathit{A}\mathit{R}}_{\mathit{w}},{\mathit{M}\mathit{E}\mathit{M}}_{\mathit{r}}$
4. $\mathit{T}\mathit{E}\mathit{M}{\mathit{P}}_{\mathit{r}}^2,\mathit{R}{\mathit{O}}_{\mathit{w}}$
5. $\mathit{M}\mathit{D}{\mathit{R}}_{\mathit{r}},\mathit{I}{\mathit{R}}_{\mathit{W}}$
Instruction fetch is first step to be done which is indicated by step 3 and 5
Then instruction decoded by cu and then operand fetch should be performed. If is indicated with step 2 and operand fetch and perform operation by step 1
$2{\mathit{R}1}_{\mathit{r}},{\mathrm{TEMP}}_{\mathit{w}}^1,{\mathit{R}}_{2\mathit{r}},{\mathrm{TEMP}}_{4\mathit{r}},{\mathrm{ALUa}}_{\mathrm{dd}},{\mathrm{TEMP}}_{\mathit{w}}^2$$\Rightarrow \{\begin{array}{c}{\mathrm{TEMP}}_1\leftarrow {\mathit{R}}_1\\ {\mathrm{TEMP}}_2⟵{\mathit{R}}_2\\ \left(\mathrm{add}\right)\mathrm{ALU}⟵{\mathrm{TEMP}}_1& {\mathrm{TEMP}}_2.\end{array}$
4. Now, write result operations should be performed. It is indicated by step 4 as result should be in Ro.
Step 4:
Hence correct order of execution should be, 3, 5, 2, 1, 4