Và lí thuyết nói thế này:Originally Posted by wit78
synchronous serial connection allows you to simultaneously send and receive information without having to wait for any signal from the
remote side. Nor does a synchronous connection need to indicate when it is beginning to send something or the end of a transmission. These
two things, plus how clocking is done, are the three major differences between synchronous and asynchronous connections—asynchronous
connections are typically used for dialup connections, such as modems.