I am very new to assembly and trying to create a very simple script to practice using stdout, stdin and cmp, I ran into the problem of my script not working when using cmp.

I have tried asking chatgpt but as you all know, it is not the most reliable tool when trying to fix errors in one´s code and I have tried some stuff that I saw online but nothing seems to work and as I am not very familiar with assembly’s syntax, I do not see any chance of me being able to fix the error on my own.

My code:

section .text
    global _start       
_start:         
    ;print question using stdout
    mov eax, 4
    mov ebx, 1
    mov ecx, question
    mov edx, len_question
    int 80h
    ;get answer using stdin
    mov eax, 3
    mov ebx, 1
    mov ecx, input
    mov edx, 1
    int 80h
    ;compare answer to right answer
    mov eax, byte input
    mov ebx, byte yes
    cmp eax, ebx
    je _right ;jump to right if right
    cmp ax, bx
    jne _wrong ;jump to wrong if wrong
    jmp _badinput ;jump to badinput if bad input
    
_right:
    ;print right message
    mov eax, 4
    mov ebx, 1
    mov ecx, msg_right
    mov edx, len_msg_right
    int 80h
    jmp _end ;jump to end
    
_wrong:
    ;print message for wrong answer
    mov eax, 4
    mov ebx, 1
    mov ecx, msg_wrong
    mov edx, len_msg_wrong
    int 80h
    jmp _end ;jump to end
    
_badinput:
    ;print message for bad input
    mov eax, 4
    mov ebx, 1
    mov ecx, msg_badinput
    mov edx, len_msg_badinput
    int 80h
    jmp _end ;jump to end
    
_end:
    ;end the program
    mov eax, 1      
    mov ebx, 0
    int 0x80  

section .data
    question db 'Is the world round?',0xa   
    msg_right db 'That´s right!'
    msg_wrong db 'That´s wrong'
    msg_badinput db 'Bad input! Choose yes (y) or no (n)!'
    yes db 'y'
    no db 'n'
    len_question    equ $ - question
    len_msg_right equ $ - msg_right
    len_msg_wrong equ $ - msg_wrong
    len_msg_badinput equ $ - msg_badinput
    
section .bss
    input resb 1

The error message is:

main.asm:17: error: mismatch in operand sizes
main.asm:18: error: mismatch in operand sizes
main.asm:65: error: symbol `msg' not defined