Problem – Write an assembly language program in 8085 microprocessor to find square of 8 bit number.
Assumption – Addresses of input data and out data are 2050 and 3050 respectively.
Approach – Combine the content of registers H and L, the resultant content can be used to indirectly point to memory location and that memory location is specified by M. To find square of any number, keep on adding that number in accumulator A which initially contains 0 by that number of times whose square we need to find.
- Assign 20 to register H, 50 to register L and 00 to accumulator A
- Load the content of memory location which is specified by M in register B
- Add content of M in accumulator A and decrement value of B by 01
- Check if B holds 00, if true then store the value of A at memory location 3050 otherwise go to step 3
|2000||MVI H 20||H <- 20|
|2002||MVI L 50||L <- 50|
|2004||MVI A 00||A <- 00|
|2006||MOV B, M||B <- M|
|2007||ADD M||A <- A + M|
|2008||DCR B||B <- B – 01|
|2009||JNZ 2007||Jump if ZF = 0|
|200C||STA 3050||M <- A|
Explanation – Registers used A, H, L, B and indirect memory M:
- MVI H 20 – initialize register H with 20
- MVI L 50 – initialize register L with 50
- MVI A 00 – initialize accumulator A with 00
- MOV B, M – moves the content of memory location which is indirectly specified by M in register B
- ADD M – add the content of memory location which is indirectly specified by M in accumulator A
- DCR B – decrement value of register B by 1
- JNZ 2007 – jump to memory location 2007 if ZF = 0, i.e register B does not contain 0
- STA 3050 – stores value of A in 3050
- HLT – stops executing the program and halts any further execution
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