Hex to BCD Conversion in Assembly Language Code
Write a Program For Hex to BCD Conversion in Assembly language .
We have a 4 digit Hex number whose equivalent binary number is to be found i.e. FFFF H. Initially we compare FFFF H with decimal 10000 ( 2710 H in Hex ). If number is greater than 10,000 we add it to DH register. Also, we subtract decimal 10,000 from FFFF H, each time comparison is made. Then we compare the number obtained in AX by 1000 decimal. Each time we subtract 1000 decimal from AX and add 1000 decimal to BX. Then we compare number obtained in AX by 100 decimals. Each time we subtract 100 decimal from AX and add 100 decimal to BX to obtain BCD equivalent. Then we compare number obtained in AX with 10 decimal. Each time we subtract 10 decimal from AX and we add 10 decimal to BX. Finally we add the result in BX with remainder in AX. The final result is present in register DH with contains the 5th bit if present and register AX.
Algorithm For Hex to BCD Conversion
Step I : Initialize the data segment.
Step II : Initialize BX = 0000 H and DH = 00H.
Step III : Load the number in AX.
Step IV : Compare number with 10000 decimal. If below goto step VII else goto step V.
Step V : Subtract 10,000 decimal from AX and add 1 decimal to DH
Step VI : Jump to step IV.
Step VII : Compare number in AX with 1000, if below goto step X else goto step VIII.
Step VIII : Subtract 1000 decimal from AX and add 1000 decimal to BX.
Step IX : Jump to step VII.
Step X : Compare the number in AX with 100 decimal if below goto step XIII
Step XI : Subtract 100 decimal from AX and add 100 decimal to BX.
Step XII : Jump to step X
Step XIII : Compare number in AX with 10. If below goto step XVI
Step XIV : Subtract 10 decimal from AX and add 10 decimal to BX..
Step XV : Jump to step XIII.
Step XVI : Add remainder in AX with result in BX.
Step XVII : Display the result in DH and BX.
Step XVIII : Stop.
Program For Hex to BCD Conversion Code
.model small
.stack 100
.code
mov ax, 0ffffh ; hex number to find it's bcd
mov bx, 0000
mov dh, 0
l9 : cmp ax, 10000 ; if ax>10000
jb l2
sub ax, 10000 ; subtract 10000
inc dh ; add 1 to dh
jmp l9
l2 : cmp ax, 1000 ; if ax>1000
jb l4
sub ax, 1000
add bx, 1000h ; add 1000h to result
jmp l2
l4 : cmp ax, 100 ; if ax>100
jb l6
sub ax, 100
add bx, 100h ; add 100h to result
jmp l4
l6 : cmp ax, 10 ; if ax>10
jb l8
sub ax, 10
add bx, 10h ; add 10h to result
jmp l6
l8 : add bx, ax ; add remainder
; to result
mov ah, 02
mov cx, 0204h ; Count to display
; 2 digits
go: rol dh, cl
mov dl, dh
and dl, 0fh
add dl, 30h ; display 2 msb digits
int 21h
dec ch
jnz go
mov ch, 04h ; Count of digits to be
; displayed
mov cl, 04h ; Count to roll by 4 bits
l12: rol bx, cl ; roll bl so that msb
; comes to lsb
mov dl, bl ; load dl with data to be
; displayed
and dl, 0fH ; get only lsb
cmp dl, 09 ; check if digit is 0-9 or letter A-F
jbe l14
add dl, 07 ; if letter add 37H else only add 30H
l14: add dl, 30H
mov ah, 02 ; Function 2 under INT 21H (Display character)
int 21H
dec ch ; Decrement Count
jnz l12
mov ah, 4cH ; Terminate Program
int 21H
end
How to Run this Program
For Running this program you should have installed Tasm on you computer . If you have not installed Tasm yet please install from Here .
C:\programs>tasm hex2bcd.asm
Turbo Assembler Version 3.0 Copyright (c) 1988, 1991 Borland International
Assembling file: hex2bcd.ASM
Error messages: None
Warning messages: None
Passes: 1
Remaining memory: 437k
C:\programs>tlink hex2bcd
Turbo Link Version 3.0 Copyright (c) 1987, 1990 Borland International
C:\programs>hex2bcd
065535
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