Table of Contents

AIM :Write a program to multiply two 8 bit numbers by repetitive addition method using 8086

Objective:

After completing this experiment, students will be able to :

understand opcode and mnemonic of the program
Draw the flowchart of the program
Write the algorithm of the program to multiply two 8-bit numbers
Write the program to multiply two numbers
Run and debug the program

System Requirement:

8086 Trainer Kit with Key Board

Setting up the Trainer Kit:

Ensure that standard IBM PC/AT system keyboard is connected
System is Powered ON
Student has a handy opcode table for programming

Flow Chart:

Logic / Algorithm

Start
Initialize the CL register to store the multiplier, clear accumulator (AL) and register BL and SI and DI register
Read the contents of the memory pointer by SI register in register CL (multiplier)
Increment the SI register.
Add accumulator with carry with the content pointed by SI
Increment the SI register content
Decrement counter (CL)
If not zero, goto step 5
If NO carry goto step 11
Store result at location pointed by DI
Increment BL
Increment DI
Save carry at location pointed by DI
Stop

Explanation of the Code:

Program Address	Op-Code	Label	Mnemonic	Comment
1000: 0200	F8		CLC	;Clear the Carry Flag
1000: 0201	BE 1300		MOV SI, 1300h	;load SI with address of multiplier
1000:0204	BF 1302		MOV DI, 1302h	;Load DI with address for storing result
1000:0207	B8 0000		MOV AX, 0000H	;Clear accumulator
1000:020A	B3 00		MOV BL, 00H	;Clear BL to store carry
1000:020C	8A 0C		MOV CL, [SI]	;Read multiplier into CL register
1000:020E	46		INC SI	;increment the source pointer to point to multiplicand
1000:020F	12 04		AGAIN: ADC AL, [SI]	;Add Accumulator with multiplicand
1000:0211	FE C9		DEC CL	;Decrement after addition
1000:0213	75 FA		JNZ AGAIN	;Repeat if not zero
1000:0215	73 02		JNC SAVE	;Check if carry and Jump to Save on NO Carry
1000:0217	FE C3		INC BL	;increment BL register to account for carry
1000:0219	88 05	SAVE:	MOV [DI], AL	;Save Product into Destination memory
1000:021B	47		INC DI	;Increment destination address
1000:021C	88 1D		MOV [DI], BL	;Save Carry
1000:021E	F4		HLT	;Stop

Execution :

Address Map for DATA

	Data Segment Address	DATA
Multiplier	Segment : Offset: 0000 : 1300
Multiplicand	Segment : Offset: 0000 : 1301

Executing The Program

	Key Pressed/Action	Display on LCD
	Press G from Keyboard	BURST or Single Step
	Press Enter	Segm_Adr
0000	Press Enter	Ofst
0200	Press Enter	Wait Cmd_Wrd=
Do not press the Reset Key; Check the result by using ub_Mir Command

Verification of Result

DATA	Multiplicand	Multiplier
1^st Data
Address SegAdr: 0000	Ofst : 1301	Ofst : 1300

Result	Carry	Product

Address SegAdr: 0000	Ofst : 1303	Ofst : 1302

Viva Question

Q.1. What is purpose of CX (CH, CL) Register?

Answer :

CX register in 8086 is a general purpose register used to hold 16-bit data
CX register is also used a counter register for applications requiring execution of LOOP for repeated operation

Q.2. How is the carry checked

Answer: 8086 microprocessor has a JNC/ JC statements to check the status of the carry flag. The control of the statement can be transferred to any location by the use of JNC or JC. In this experiment we used JNC SAVE to jump to location SAVE when there is no carry as a result of addition. If the statement becomes false on execution then the immediate next instruction (inc BL in this experiment) is executed.

Q.3. Explain how the multiplication of two numbers can be obtained by addition operation

Answer: Multiplication in fact the repeated operation of addition. For this purpose we set the counter value with multiplier and add the multiplicand with itself number of times as given by multiplier.

Experiment Number 2