section .data letter db 'A' global _start _write: mov edx, 1 mov ecx, letter mov ebx, 1 mov eax, 4 ; ssize_t sys_write(unsigned int fd, const char * buf, size_t count) int 0x80 inc BYTE [letter] _start: cmp BYTE [letter], 'Z' jle _write cmp BYTE [letter], '[' ; Z + 1 je _add cmp BYTE[letter], 'z' jle _write xor ebx, ebx mov eax, 1 int 0x80 _add: add BYTE [letter], 6