Serial and parallel interfaces
Serial and parallel ports problem, then re-testing time postgraduate or a face questions, vaguely remember wrong, and asked: Do you think fast or fast serial parallel port, explain. Then it should be wrong, hey, solid foundation, the earth was shaking.
Serial interface:
A serial interface, the serial port for short, is a COM interface, the interface is the use of extended serial communication protocol, the data transmission rate is 115kbps ~ 230kbps.
Refers to the data are sequentially transmitted one bit , which is characterized by a communication line is simple , as long as the pair of transmission lines can be two-way communication, and can use a telephone line. Lower costs, applicable to long-distance communication, but the transmission is slow .
Parallel Interface:
Parallel interface, referred to as parallel, i.e. LPT interfaces, is the use of parallel communication protocol extension interface. Parallel data transfer rate eight times faster than the serial port, parallel port standard data transmission rate 1Mbps.
Parallel interface means you simultaneously transmit data , characterized by transmission speed (1Mbps), but when the transmission distance, the number of bits during the addition, causing the communication line is complicated and costs increase.
Speed difference
Popular speak, as only one lane serial port, and parallel port is to have eight lanes at a time can transmit 8 (a byte). Parallel but not fast, since the mutual interference between the eight channels. Transmission speed is limited. And transmission error, at the same time to re-transmit data of 8 bits. Serial no interference, the transmission error retransmission thought on it. So faster than serial parallel port. Serial hard disk is so valued.
Differences hard drive serial and parallel ports of
There are serial SATA interface hard disk, it is the same reason, the reason why it can 150MB / s transmission speed, thanks to its serial manner, several parallel signals at a relatively high frequency are not well solve the interference between them, so now ATA 13MBb / s hard disk has come to limit parallel, replaced by STAT. Another of the 80 channel parallel data lines ATA100 hard disk, where there is the ground 40, is used to prevent interference between the parallel signals; STAT that speed nominal bit / s, the actual speed is 150M / 300M now the fastest hard drive speed single block was less than 100MB / s, are common in the speed of 40-60MB / s; and remember! ! ! The interface is not the bottleneck.