The serial port receives and sends one bit at a time;
Parallel port, multiple data paths are sent or received at the same time;
The parallel port is not necessarily more efficient than the serial port;
The name already contains the meaning of serial port:
USB：Universal Serial Bus
SAS：Serial Attached SCSI
SATA ：Serial ATA
PCIe is also a serial port;
1. Limitations of parallel port communication
The bits on each data path are not required to be synchronized, but when arriving at the receiving end, the fast-transmitting bits must wait for the slow-transmitting bits;
crosstalk: crosstalk (note that crosstalk occurs in parallel port communication, not serial port): crosstalk is the coupling between two signal lines, the mutual inductance and mutual capacitance between the signal lines causing noise on the line. Capacitive coupling induces coupling current, while inductive coupling induces coupling voltage.
Although the performance of twisted pair is constantly improving, there is a parameter that has been with twisted pair like a ghost, and with the development of twisted pair, this parameter is becoming more and more important. This parameter is -- crosstalk (Crosstalk).
Parallel port: occupies a large number of pins to support parallel port data transmission;