8085 Program to Add 10 Data Starting From Specific Memory Address

Let us suppose that 10 data’s are stored in memory location from 9000H to 9009H. These data’s are to be added and let us store the result in memory location 9100H.

Algorithm:

1. Start.
2. Load into register pair HL from memory location 9000H.
3. Load into register pair DE from memory location 9100H.
4. Move 09 into register C as counter.
5. Move the content of memory M into accumulator A.
6. Increment register pair HL by 1.
7. Add content of memory M with the contents of the accumulator A.
8. Decrement value of register C by 1.
9. If no zero is present, go to step 6 else go to step 10.
10. Store the content of accumulator A into memory location pointed by register pair DE.
11. Terminate the program.

Program Code:

LXI H, 9000H

LXI D, 9100H

MVI C, 09H

MVI B, 00H

MOV A, M

UP:

INX H

ADD M

JNC DOWN

INR B

DOWN:

DCR C

JNZ UP

STAX D

MOV A, B

STA 9101H

HLT

Register pair HL is loaded from memory location 9000H and register pair DE is loaded from memory location 9100H (For understanding, loaded can be referred to as pointed). 09 is moved into register C so as to use it as counter. Register B is initialized with value 00 to count the carry generated during the addition. The content of memory M (i.e. the first data which is stored in memory location 9000H) is moved into the accumulator A. Register pair HL is incremented by 1 (now it points to the second data i.e. stored in memory location 9001H) and the contents of memory M is added with the contents of the accumulator and the result is stored in the accumulator. If carry is generated during addition then the register B is incremented by 1, if no carry is generated then the instruction

INR B

is skipped and the content of register C is decremented by 1. The register pair HL in again incremented by 1, content of memory M is added with accumulator A and the condition of borrow is checked again and the counter is decreased by 1. These steps are repeated as long as the counter is greater than 0. When the counter is 0, it means that all the 10 data has been added. Now, the content of accumulator (which is the sum value) is stored into memory location pointed by register D. The content of register B is moved into accumulator and is stored into memory location 9101H which is the carry value.

Output:

Example 1

                                                     

Example 2

In these two examples, the data from address 9000 to 9009 is added and the sum is stored in address 9100 and the carry is stored in 9101.