Program – Write an assembly language program in 8085 microprocessor to count even numbers in series of 10 numbers.
Assumption – Ten 8-bit numbers are 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 1.
- Store value of M in accumulator A.
- Check whether the content in A is even or odd by performing AND operation of A with 01.
- If content of A is 00 after AND operation then number scanned was even, If so then increment C by 01 else if content of A is 01 after AND operation then number scanned was odd, If so then decrements D by 01.
- Check if zero flag is not set i.e. ZF = 0 then jump to step 3 otherwise store value of C at 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||ANI 01||A <- A (AND) 01||200B||JNZ 200F||Jump if ZF = 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||2017||HLT||END|
Explanation – Registers A, B, C, D, H, L are used for general purpose.
- LXI H 204F: assign 20 to H and 4F to L.
- MVI C, 00: assign 00 to C.
- MVI D, 0A: assign 0A to D.
- INX H: increment indirect memory location M by 01.
- MOV A, M: move content of M to A.
- ANI 01: perform AND operation of A with 01 and store the result in A.
- JNZ 200F: jump if ZF = 0 to memory location 200F.
- INR C: increment C by 01.
- DCR D: decrements D by 01.
- JNZ 2007: jump if ZF = 0 to memory location 2007.
- MOV A, C: moves the content of C to A.
- STA 3050: store the content of A to memory location 3050.
- HLT: stops executing the program and halts any further execution.
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