Question

I made this 8086 assembly program for string comparison, but it contains an infinite loop. I have checked and rechecked. Can anyone find where i am wrong?

org 100
jmp start
str1: db "hello$"
str2: db "ello$"


start: 
lea bx,str1
mov si,bx
lea ax,str2
mov di,ax  
mov ax,1234
jmp compare

compare:
mov bl,[si]
cmp [di],bl
jne notequal
cmp bx,'$'
je equal
inc si
inc di
jmp compare

notequal:
mov ax,0000h 
hlt

equal:
mov bx,0001h
hlt
  ret         

Answer 1

I don’t know what you checked and rechecked, but you’re reading bytes from one of the strings into bl and yet comparing the entire bx with ‘$’ instead of comparing bl with ‘$’.

Did you consider debugging your code???

Also I don’t know why you use hlt. If interrupts are disabled, your program will never return.

Finally, if this is a .COM program for DOS, there’s a “little” difference between org 100 and org 100h.