Problem – Write an assembly language program in 8085 microprocessor to count number of elements which are less than 0A in series of 10 numbers.
Assumption – Series of 10 numbers is stored from starting memory location 2050. Value of count is stored at memory location 3050
- 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.
|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 <- A|
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
Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.