8085 program to count number of once in the given 8-bit number

In this program we will see how to count number of 1's in an 8-bit number.

Problem Statement

Write 8085 Assembly language program to count number of 1s in 8-bit number stored atlocation 8000H.

Discussion

In this program we areusing the rotate operation to count the number of 1's. As there are8 different bits in 8-bit number, then we are rotating the numbereight times. we can use RRC or RLC. Here we have used the RRCinstruction. This instruction sends the LSb to MSb also to carryflag. So after each iteration we can check the carry status to getthe count of 1s.

If the number is DA (11011010) then the answer will be 5, as there are five 1s in the number.

Input

Address	Data
. . .	. . .
8000	DA
. . .	. . .

Flow Diagram

Program

Address	HEX Codes	Labels	Mnemonics	Comments
F000	37		STC	Set Carry
F001	3F		CMC	ComplementCarry
F002	3A, 00, 80		LDA 8000H	Load the number into A
F005	0E, 08		MVI C,08H	Initialize the counter to 08H
F007	06, 00		MVI B,00H	Clear B register
F009	0F	LOOP	RRC	Rotate right
F00A	D2, 0E, F0		JNC SKIP	If CY = 0,skip the next step
F00D	04		INR B	If CY = 1,increase B
F00E	0D	SKIP	DCR C	Decrease C by1
F00F	C2, 09, F0		JNZ LOOP	If Z = 0,jump to loop
F012	78		MOV A,B	Load the count to A
F013	32, 50, 80		STA 8050H	Store the result at 8050H
F016	76		HLT	Terminate the program