Question

When silicon chips are fabricated, defects in materials (e.g., silicon) and manufacturing errors can result in defective circuits. A very common defect is for one signal wire to get "broken" and always register a logical 0. This is often called a "stuck-at-0" fault. 4.4.1 (5) Which instructions fail to operate correctly if the MemToReg wire is stuck at 0? 4.4.2 (5) <$4.4> Which instructions fail to operate correctly if the ALUSrc wire is stuck at 0? 4.4.3 (5) <$4.4> Which instructions fail to operate correctly if the Reg2Loc wire is stuck at 0?

Answer 1

Instructions relying on the MemToReg wire, such as loading data from memory to registers, will fail if it's stuck at 0. The ALUSrc wire being stuck at 0 affects instructions needing an immediate value or a second register's value for the ALU. The Reg2Loc wire being stuck at 0 leads to the failure of instructions requiring a second register's value for input or write-back.

Step-by-step explanation:

When dealing with the manufacturing errors in silicon chip fabrication, such as a stuck-at-0 fault, various instruction executions can be affected depending on which wire is stuck. If the MemToReg wire is stuck at 0, it would mean that the instruction that writes data from memory to the register would fail. This typically affects instructions like load commands where the expectation is to load a value from memory into a register.

For the ALUSrc wire being stuck at 0, instructions where the ALU (Arithmetic Logic Unit) requires an immediate value or a value from a second register would fail. This affects operations that perform arithmetic or logic functions that are not solely based on register values.

Last, if the Reg2Loc wire is stuck at 0, instructions that would normally use a second register's value as the ALU input would fail, or instructions expecting to write back to a second register location would give incorrect results.