8085 program to add three 16 bit numbers stored in registers
Problem – Write an assembly language program to add three 16 bit numbers stored in register HL, DE, BC and store the result in DE with minimum number of instructions.
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- Numbers to be added are already stored in register HL, DE, BC
- Numbers stored in register are such that final result should not be greater than FFFF
DAD D performs the following task:
H <- H + D L <- L + E
DAD instruction take one argument and that argument can be register B, D, H or SP XCHG instruction exchanges the content of register D with H and E with L
- Add the content of DE register in HL and store the result in HL by help of DAD instruction
- Move the content of register B in D and C in E
- Repeat step 1
- Use XCHG instruction to swap the content of DE with HL. We will get the result in DE
|2000||DAD D||H <- H + D, L <- L + E|
|2001||MOV D, B||D <- B|
|2002||MOV E, C||E <- C|
|2003||DAD D||H <- H + D, L <- L + E|
|2004||XCHG||Swap content of HL with DE|
- DAD D – adds the content of register D in H and register E in L and store the result in HL
- MOV D, B – moves the value of register B in register D
- MOV E, C moves the value of register C in register E
- Same as step 1
- XCHG – exchange the content of register H with register D and L with E.
- HLT – stops executing the program and halts any further execution