 Small-form-factor systems and laptops may omit RS-232 connector ports to conserve space, but the electronics are still there.RS-232 has been standard for so long that the circuits needed to control a serial port became very cheap and often exist on a single chip, sometimes also with circuitry for a parallel port.The individual signals on a serial port are unidirectional and when connecting two devices the outputs of one device must be connected to the inputs of the other.