GATE CSE 2000 | Question: 11 closed

Question

Consider the following 8085 program segment, where registers B and C contain BCD values:

S1: MVI           A, 99H 
    MVI           D, 00H
    SUB           C
    ADD           B
    DAA

---

S2: JC             S3
   MOV             E, A
   MVI             A, 99H
   SUB             E
   MOV             E, A
   JZ              S4
   MVI             D, FFH
   JMP             S4

---

S3:INC             A
   DAA 
   MOV             E, A

---

S4: .........

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1. For the two pairs (B = 44, C = 25) and (B = 33, C = 46) at S1,
   1. Find the values in register A when control reaches S2.
   2. Find the values in register D and E when control reaches S4.
2. What, in general, is the value of D and E as a function of B and C when control reaches S4?