The Knowledge Adda

Assumption: We have to write a program to convert 2-digit BCD into Binary Number. For example 67= 6 * 0A (10) +7= 3CH+7= 43 H. We have to store number at 2200 H and store output at 2300 H.

Algorithm:

Program:

Memory Address	Op-code	Operand	Comments
2000	LDA	2200 H	Get BCD digit
2003	MOV	B,A	Store number in B
2004	ANI	0F	Mask MSB four bits
2006	MOV	C,A	Save unpacked BCD1 in C
2007	MOV	A,B	Get BCD again
2008	ANI	F0H	Make LSB BCD digit zero
200A	RRC		Convert MSB into unpacked BCD2
200B	RRC
200C	RRC
200D	RRC
200E	MOV	B,A	Save unpacked BCD2 in register
200F	XRA	A	Clear Accumulator
2010	MVI	D,0AH	Set D as multiplier of 10
2012	ADD	D	Add D with Accumulator
2013	DCR	B	Decrement B
2014	JNZ	2012	Jump multiplication is no complete
2017	ADD	C	Add BCD1 with accumulator
2018	STA	2300 H	Store the result
201B	RST	5	Set Breakpoint(optional)
201C	END		End the program

Used Instruction: 

LDA address: Load data into register A (accumulator) directly from the address given within the instruction.

RRC: Each binary bit of the accumulator is rotated right by one. Bit D7 is placed in the position of B0 as well as carry flag.

ANI: This instruction logically ANDs the 8-bit data given in the instruction with the contents of accumulator and stores the result in the accumulator. 

MOV: This instruction is used to copy the content from source register to destination register.

JNZ: Jump if counter is not zero at target address.

XRA: It perform Ex-or operations with accumulator 

ADD: This instruction is used to add the content of specified register to the content of accumulator and store output in accumulator.

STA: This instruction is used to store the content of accumulator at specified memory address.

RST 5: This instruction is used to set breakpoint for the execution.

END: This instruction is used to execute the program.

 

Result:  

Input: 2200 H-67

Output: 2300 H-43 H             

 

Procedure to look output