5. Refer to the u-instruction formatencoding from Lecture 12. What would be the

Question

5. Refer to the u-instruction formatencoding from Lecture 12. What would be the binary code stored in the CW(Control Word) corresponding to the instruction MDR-Mem[MARI? You are allowed to show only the values for the CW bits relevant to this instruction. Memory Control Group ALUIRegs Control Group Branches EnblRes Addr Res Memory Addr A Addr B Sel mem Const Wr_MAR Sel A Sel_B MAR Wr_MDR MDR Wr IR IR ALU Op. Wr PC D_ready - RIW To Control Unit Answer: Sel mem 0 Wr_MDR1 RW-1 EnbIRes 0 Addr A X Addr B X Sel A=X Sel B X OP X

Explanation / Answer

Operation is MDR <- M[MAR] which means MAR contains Address we need to read that location from memory, then load that data into MDR register. no other operation will we done during this operation.

So Register file, IR will not be affected.

so not to effect IR, wr_IR will be 0

so not to effect Register file EnblRes will be zero, so what ever ALU perform that no going to affect Register file. so Addr_A=X, Addr_B=X, Sel_A=X, Sel_B=X, OP=X.

Sice MAR already contaiins address we should not change that so wr_MAR=0.

To select particular location to memory pointed by MAR, Sel_mem will be zero so MAR will be selected.

So now to read That memory location R/W' will be 0 to perform read opeation

Now to write that selected Data to MDR, wr_MDR will be 1.

please give thumbs up, thanks

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