Typo, "WHITE_OB_BLACK" should be 'WHITE_ON_BLACK'
@ -10,7 +10,7 @@ print_string_pm:
print_string_pm_loop:
mov al, [ebx] ; [ebx] is the address of our character
mov ah, WHITE_OB_BLACK
mov ah, WHITE_ON_BLACK
cmp al, 0 ; check if end of string
je print_string_pm_done