I need a professional explanation for a scasb emu8086 code in 3 page as a word text

; this sample shows how to use scasb instruction to find a symbol.

org 100h

jmp start

str1 db 'aaabbbxddd'

s_found db '"yes" - found!', 0Dh,0Ah, '$'

s_not db '"no" - not found!', 0Dh,0Ah, '$'

find_what equ 'x'

start:

; set forward direction:

cld

; set counter to string size:

mov cx, 10

; load string address into es:di

mov ax, cs

mov es, ax

lea di, str1

; we will look for the character in string:

mov al, find_what

repne scasb

jz found

not_found:

; "no" - not found!

mov dx, offset s_not

mov ah, 9

int 21h

jmp exit_here

found:

; "yes" - found!

mov dx, offset s_found

mov ah, 9

int 21h

; di contains the address of searched character:

dec di

; wait for any key press...

mov ah, 0

int 16h

exit_here:

ret