Ex.
No: 1 Write an assembly language program for 8 bit and 16 bit addition with and without
carry
Aim: To write an assembly language program to add two 8 bit and 16 bit numbers with and without
carry
Apparatus required: 1. Microcontroller 8051 kit with clock frequency 12MHz.
2. Microcontroller kit manual
a) Addition of two 8 bit numbers without carry
Algorithm:
1. Load the first data from memory to accumulator using DPTR register as address pointer.
2. Move the accumulator content into R0 register.
3. Load the second data from memory to accumulator using DPTR register as address pointer
4. Add the content of R0 register with Accumulator
5. Store the result in memory
6. Stop.
Flowchart:
Program:
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
4000 MOV DPTR, #4200 90 Move the given 16 bit data to Data Pointer
4001 42
4002 00
Move the contents whose address stored in
4003 MOVX A, @DPTR E0
DPTR to A register
4004 MOV R0, A Move the contents of A register to R0
4005 INC DPTR A3 Increment Data pointer
Move the contents whose address stored in
4006 MOVX A, @DPTR E0
DPTR to A register
4007 ADD A, R0 Add the contents of R0 with Accumulator
4008 INC DPTR A3 Increment Data pointer
Move the result from A register to the
4009 MOVX @DPTR, A F0
memory address stored in DPTR
400A Halt: SJMP Halt 80 Short jump here (HLT)
400B FE
I/P and O/P Verification Table
Input Output
Address Data Address Data
4200 49H 4202 BEH
4201 75H
Result:
The assembly language programs for 8 bit and 16 bit addition with and without carry are written and
executed successfully with the given test data.
b) Addition of two 8 bit numbers with carry
Algorithm:
1. Load the first data from memory to R0 through accumulator using DPTR register as address
pointer.
2. Load the second data from memory to accumulator using DPTR register as address pointer
3. Add the content of R0 register with Accumulator.
4. Check if carry arrives or not. If so store the carry in R1 register
4. Store the result and carry in memory.
5. Stop.
Flowchart:
Program:
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV R1, #00H
MOV DPTR, #4200
MOVX A, @DPTR
MOV R0, A
INC DPTR
MOVX A, @DPTR
ADD A, R0
JNC Loop1
INC R1
Loop1: INC DPTR
MOVX @DPTR, A
INC DPTR
MOV A,R1
MOVX @DPTR, A
Halt: SJMP Halt
c) Addition of two 16 bit numbers without carry
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV DPTR, #4200
MOVX A, @DPTR
MOV R0, A
MOV DPTR, #4202
MOVX A, @DPTR
ADD A, R0
MOV DPTR, #4250
MOVX @DPTR, A
MOV DPTR, #4201
MOVX A, @DPTR
MOV R0, A
MOV DPTR, #4203
MOVX A, @DPTR
ADDC A, R0
MOV DPTR, #4251
MOVX @DPTR, A
Halt: SJMP Halt
d) Addition of two 16 bit numbers with carry
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV R1, #00H
MOV DPTR, #4200
MOVX A, @DPTR
MOV R0, A
MOV DPTR, #4202
MOVX A, @DPTR
ADD A, R0
MOV DPTR, #4250
MOVX @DPTR, A
MOV DPTR, #4201
MOVX A, @DPTR
MOV R0, A
MOV DPTR, #4203
MOVX A, @DPTR
ADDC A, R0
JNC Loop1
INC R1
Loop1: MOV DPTR, #4251
MOVX @DPTR, A
INC DPTR
MOV A,R1
MOVX @DPTR, A
Halt: SJMP Halt
e) 8 bit Subtraction
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV R1, #00H
MOV DPTR, #4200
MOVX A, @DPTR
MOV R0, A
INC DPTR
MOVX A, @DPTR
SUBB A, R0
INC DPTR
MOVX @DPTR, A
Halt: SJMP Halt
8 bit Subtraction (alternative method)
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV R1, #00H
MOV DPTR, #4200
MOVX A, @DPTR
MOV R0, A
INC DPTR
MOVX A, @DPTR
SUBB A, R0
JNC Loop1
CPL A Take one’s complement
INC A Find two’s complement
INC R1 Make R1 as 01 to represent a negative result
Loop1: INC DPTR
MOVX @DPTR, A
INC DPTR
MOV A,R1 Store the sign value
MOVX @DPTR, A
Halt: SJMP Halt
f) 16 bit Subtraction
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV DPTR, #4200
MOVX A, @DPTR
MOV R0, A
MOV DPTR, #4202
MOVX A, @DPTR
SUBB A, R0
MOV DPTR, #4250
MOVX @DPTR, A
MOV DPTR, #4201
MOVX A, @DPTR
MOV R0, A
MOV DPTR, #4203
MOVX A, @DPTR
SUBB A, R0
MOV DPTR, #4251
MOVX @DPTR, A
Halt: SJMP Halt
2) Waveform Generator
a) Stair Case Generator
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV A, #80H
MOV DPTR, CWR
MOVX @DPTR, A
MOV DPTR, #Port A
Again: MOV R0, #0AH
CLR A
Repeat: MOV @DPTR, A
INC A
ACALL Delay1
DJNZ R0, Repeat
SJMP Again
Halt: SJMP Halt
b) Sine Wave Generator
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV A, #80H
MOV DPTR, CWR
MOVX @DPTR, A
Again: MOV R1, #00
MOV R2, #42
MOV R0, #46
Repeat: MOV DPL, R1
MOV DPH, R2
MOVX A, @DPTR
INC DPTR
MOV R1, DPL
MOV R2, DPH
MOV DPTR, #Port A
MOV @DPTR, A
ACALL Delay1
DJNZ R0, Repeat
SJMP Again
Halt: SJMP Halt
c) Square Wave Generator
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV A, #80H
MOV DPTR, CWR
MOVX @DPTR, A
Again: MOV DPTR, #Port A
MOV A, #00H
MOV @DPTR, A
ACALL Delay1
MOV A, #01H
MOV @DPTR, A
ACALL Delay1
SJMP Again
Halt: SJMP Halt
d) Triangular Wave generator
Addres Mnemonics
Label Hexcode Comment
s Opcode Operand
MOV A, #80H
MOV DPTR, CWR
MOVX @DPTR, A
MOV DPTR, #Port A
Start: MOV A, #00H
Again: MOV @DPTR, A
INC A
JNZ Again
MOV A, #0FFH
Repeat: MOV @DPTR, A
DEC A
JNZ Repeat
SJMP Start
Halt: SJMP Halt
