4.2
Extend the src instruction set by adding the instruction swap ra, rb, (op = 7), that exchanges the contents of the two specified registers. (4.4)
a. Define a plausible abstract rtn for this instruction
Answer: swap (:=op=7)  R[rb]  R[ra]: R[ra]  R[rb]
b. Develop the concrete RTN for it, assuming the 1-bus SRC micro architecture
Answer:
T0 MA <- PC: C <- PC + 4;
T1 MD <- M[MA]: PC <- C;
T2 IR <- MD;
T3 A <- R[ra];
T4 B <- R[rb];
T5 R[rb] <- A;
T6 R[ra] <- B;