8085 Micro-Processor Programs

Factorial of a number using 8085

Ø   An Assembly Language Program to find the factorial of a number using 8085?

Algorithm

1)      Load HL pair with the number whose factorial is to be found.

2)      Copy memory content to register E.

3)      Decrement register B content by 1.

4)      Increment the memory and decrement the number and store the numbers in the consecutive memory locations.

5)      Again load the number to the HL pair.

6)      Copy the number to the accumulator.

7)      Increment memory and copy the second number to register B.

8)      Copy the accumulator content to the register C as count.

9)      Initialize accumulator with 0.

10)  Add accumulator content with register B.

11)  Decrement count.

12)  If count = 0, then got next step else go to step 8.

13)  Copy accumulator content to memory

14)  Decrement register E by 1.

15)  If register E is not zero then go to step 6 else go to next step.

16)  Store the factorial in memory.

17)  Terminate the program.

Program

MEMORY	LABEL	MNEMONIC	HEX CODE	COMMENT
4200		LXI H,4100	21	Load the number to the HL pair
4201			00
4202			41
4203		MVI C,M	4E	Copy the number to register C
4204		MVI E,M	5E	Copy memory content to E
4205		DCR E	1D	Decrement E
4206	LOOP1	INX H	23	Increment memory
4207		DCR C	0D	Decrement C
4208		MOV M,C	71	Copy content of C to memory
4209		JNZ LOOP1	C2	Jump on non-zero to label LOOP1
420A			06
420B			42
420C		LXI H,4100	21	Load the number whose factorial is to be found in HL pair
420D			00
420E			41
420F	LOOP2	MOV A,M	7E	Copy memory content to accumulator
4210		INX H	23	Increment memory
4211		MOV B,M	46	Copy memory content to B
4212		MOV C,A	4F	Copy accumulator content to C
4213		MVI A,00	3E	Initialize A with 0
4214			00
4215	GO	ADD B	80	[A] ß [A] + [B]
4216		DCR C	0D	Decrement C
4217		JNZ GO	C2	Jump on non-zero to label GO
4218			15
4219			42
421A		MOV M,A	77	Copy accumulator content to memory
421B		DCR E	1D	Decrement E
421C		JNZ LOOP2	C2	Jump on non-zero to label LOOP2
421D			0F
421E			42
421F		STA 4500	32	Store accumulator content to memory
4220			00
4221			45
4222		HLT	76	Program ends

Observation

Input at           4100    :           05_H

Output at         4500    :           78_H        ----------- factorial

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Square of an 8-bit number using 8085

Ø   An Assembly Language Program to find the square of an 8-bit number using 8085?

Algorithm

1)      Load the HL pair with the number whose square is to be found.

2)      Copy the number to C and B registers.

3)      Initialize D and A registers with 0.

4)      Add content of accumulator with register B.

5)      Check for carry.

6)      If no carry go to step 8 else go to next step.

7)      Increment content of D.

8)      Decrement content of C.

9)      If ZF = 0 then go to next step else go to step 4.

10)  Store the product and carry in memory.

11)  Terminate the program.

Program

MEMORY	LABEL	MNEMONIC	HEX CODE	COMMENT
4200		LXI H,4500	21	Load the number to the HL pair
4201			00
4202			45
4203		MVI A,M	7E	Copy the number to the accumulator
4204		MVI B,A	47	Copy the accumulator content to register B
4205		MVI D,00	16	Initialize D with 0
4206			00
4207		MOV C,A	4F	Copy accumulator content to C
4208		MOV A,D	7A	Copy content of D to accumulator
4209	GO	ADD B	80	[A] ß [A] + [B]
420A		JNC AHEAD	D2	Jump on no carry to the label AHEAD
420B			0E
420C			42
420D		INR D	14	Increment D
420E	AHEAD	DCR C	0D	Decrement C
420F		JNZ GO	C2	Jump on non-zero to the label GO
4210			09
4211			42
4212		STA 4100	32	Store the product to 4100
4213			00
4214			42
4215		MOV A,D	74	Copy carry to accumulator
4216		STA 4101	32	Store carry to 4101
4217			01
4218			41
4219		HLT	76	Program ends

Observation

Input at           4100    :           05_H

Output at         4100    :           19_H      ----------- Square

                        4101    :           00_H      ----------- Carry

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