Microprocessor 8085 Assembly Language Programs

Statement: Multiply two 8-bit numbers stored in memory locations 2200H and 2201H by repetitive addition and store the result in memory locations 2300H and 2301H.

LDA 2200H
MOV E, A
MVI D, 00 : Get the first number in DE register pair
LDA 2201H
MOV C, A : Initialize counter
LX I H, 0000 H : Result = 0
BACK: DAD D : Result = result + first number
DCR C : Decrement count
JNZ BACK : If count 0 repeat
SHLD 2300H : Store result
HLT : Terminate program execution

Statement: Write a set of instructions to alter the contents of flag register in 8085.

PUSH PSW : Save flags on stack
POP H : Retrieve flags in 'L'
MOV A, L : Flags in accumulator
CMA : Complement accumulator
MOV L, A : Accumulator in 'L'
PUSH H : Save on stack
POP PSW : Back to flag register
HLT :Terminate program execution

Statement:Find the number of negative elements (most significant bit 1) in a block of data. The length of the block is in memory location 2200H and the block itself begins in memory location 2201H. Store the number of negative elements in memory location 2300H.

LDA 2200H
MOV C, A : Initialize count
MVI B, 00 : Negative number = 0
LXI H, 2201H : Initialize pointer
BACK: MOV A, M : Get the number
ANI 80H : Check for MSB
JZ SKIP : If MSB = 1
INR B : Increment negative number count
SKIP: INX H : Increment pointer
DCR C : Decrement count
JNZ BACK : If count 0 repeat
MOV A, B
STA 2300H : Store the result
HLT : Terminate program execution

Statement: Two digit BCD number is stored in memory location 4200H. Unpack the BCD number and store the two digits in memory locations 4300H and 4301H such that memory location 4300H will have lower BCD digit.

LDA 4200H : Get the packed BCD number
ANI FOH : Mask lower nibble
RRC
RRC
RRC
RRC : Adjust higher BCD digit as a lower digit
STA 4301H : Store the partial result
LDA 4200H : .Get the original BCD number
ANI OFH : Mask higher nibble
STA 4201H : Store the result
HLT : Terminate program execution