Answer to Question #243863 in Electrical Engineering for Prem

Question

PC = 41, DR = 1206

Now perform the below given task 

AR  PC

M[AR] DR

IR M[AR]  

Explain the contents of the memory after the execution of second instruction. 

Answer 1

PC = 41, DR = 1206

AR  PC

M[AR] DR

IR M[AR]  

T1 : IR ¬ M[AR], PC ¬ PC + 1

• To be able to compose the instruction, we must decode and prepare to fetch the operand. In the

event it is an indirect operand, we need to have the indirect addressing bit as well:

• T2 : D0 , … D7 ¬ Decode IR(12-14), AR ¬ IR (0-11), I ¬ IR(15)

BSA is used to branch to a subprogram. This requires saving the return address, which is saved

at the operand’s effective address with the subprogram beginning one word later in memory: •

D5T4 : M[AR] ¬ PC, AR ¬ AR + 1 D5T5 : PC ¬ AR, SC ¬ 0