8085 program to count number of elements which are less than 0A
Problem – Write an assembly language program in 8085 microprocessor to count number of elements which are less than 0A in series of 10 numbers.
Example –
Assumption – Series of 10 numbers is stored from starting memory location 2050. Value of count is stored at memory location 3050
Algorithm –
- Initialize register H with 20 and register L with 4F so that indirect memory points to memory location 204F.
- Initialize register C with 00 and register D with 0A.
- Increment indirect memory by 01.
- Move the content of M in accumulator A.
- Compare the content of A with 0A by help of CPI instruction. This instruction will update flags of 8085.
- Check if carry flag is set, if true then increment content of C by 01.
- Decremented content of D by 01.
- Check if zero flag is reset, if true then jump to step 3.
- Move the content of C to A.
- Store the content of A to memory location 3050.
Program –
MEMORY ADDRESS | MNEMONICS | COMMENT |
---|---|---|
2000 | LXI H 204F | H <- 20, L <- 4F |
2003 | MVI C, 00 | C <- 00 |
2005 | MVI D, 0A | D <- 0A |
2007 | INX H | M <- M + 01 |
2008 | MOV A, M | A <- M |
2009 | CPI 0A | A – 0A |
200B | JNC 200F | Jump if CY = 0 |
200E | INR C | C <- C + 01 |
200F | DCR D | D <- D – 01 |
2010 | JNZ 2007 | Jump if ZF = 0 |
2013 | MOV A, C | A <- C |
2014 | STA 3050 | M[3050] <- A |
2017 | HLT | END |
Explanation – Registers A, C, D, H, L are used for general purpose.
- LXI H 204F: assign 20 to register H and 4F to register L
- MVI C, 00: assign 00 to register C
- MVI D, 0A: assign 0A to register D
- INX H: increment indirect memory location by 01
- MOV A, M: moves the content of indirect memory location M to accumulator A
- CPI 0A: subtracts 0A from content of A and update the flags of 8085
- JNC 200F: jump to memory location 200F if CY = 0
- INR C: increment content of C by 01
- DCR D: decrement content of D by 01
- JNZ 2007: jump to memory location 2007 if ZF = 0
- MOV A, C: moves the content of C to A
- STA 3050: store the content of A in memory location 3050
- HLT: stops executing the program and halts any further execution
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