8085 Program to check for two out of five code

Now let us see a program of Intel 8085 Microprocessor. This program will help us to check a given value is a valid 2 out of 5 code or not.

Problem Statement:

Write 8085 Assembly language program to check whether a given number is 2 out of five code or not. The number is stored at location 8000H.

Discussion:

The checking of two out of five code is simple. At first we have to check the higher order three bits are 0 or not. If they are 0, then we will check next five bits. If there are exactly two 1s in these 5-bits, then it is a valid 2 out of 5 code.

Here at first we are ANDing the number by (1110 0000), if the first three bits are 0, then the result will be 0, after that we are checking the number of 1s by using rotating operation. Using rotation operation if the carry flag is enabled, then the count will be increased. Thus the total count of 1s will be reflected.

This program will store FFH into location 8050H if the number is valid 2 out of 5 code, otherwise it will store 00H into 8050H.

Input:

First Input

Address	Data
. . .	. . .
8000	12
. . .	. . .

Second Input

Address	Data
. . .	. . .
8000	13
. . .	. . .

Third Input

Address	Data
. . .	. . .
8000	03
. . .	. . .

Flow Diagram:

Program:

Address	HEX Codes	Labels	Mnemonics	Comments
F000	3A, 00, 80		LDA 8000H	Load the number from memory
F003	67		MOV H,A	Load A to H
F004	2E, 00		MVI L,00H	Clear register L
F006	E6, E0		ANI E0H	AND Acc and 11100000b
F008	C2, 21, F0		JNZ DONE	If Z = 0, go to Done
F00B	7C		MOV A,H	Load H to A
F00C	0E, 05		MVI C,05H	Load C with 05H for counting
F00E	16, 00		MVI D,00H	Clear register D
F010	0F	LOOP	RRC	Rotate acc content to the right
F011	D2, 15, F0		JNC SKIP	If CY = 0, jump to skip
F014	14		INR D	Increase D by 1
F015	0D	SKIP	DCR C	Decrease C by 1
F016	10, F0		JNZ LOOP	Jump to LOOP
F019	3E, 02		MVI A,02H	Initialize A with 02H
F01B	BA		CMP D	Compare D with A
F01C	C2, 21, F0		JNZ DONE	if Z = 0, go to DONE
F01F	2E, FF		MVI L,FFH	Load L with FFH
F021	7D	DONE	MOV A,L	Take result from L to A
F022	32, 50, 80		STA 8050H	Sore result at 8050H
F025	76		HLT	Terminate the program