 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2017/digital-systems-linear-algebra-introduction-to-formal-proof/3/b/i/solution

Keep storage only for registers 1 through 31, return a hardwired all-zero word on either read port when its address is zero, and set

w e_{i} = [wa = i], i = 1, \dots, 31.

There is no enable for register zero and no global RegWrite input to this register file. The right-hand diagram above shows this change. Every clock edge may select a write address; choosing zero suppresses all physical register enables. Consequently the MIPS zero register acts as a write-suppression destination.

 New to topics? Read the docs here!