Serial data and parallel data are relative concepts. Serial data refers to the data transmitted by each data bit in order during transmission, while parallel data refers to the data transmitted by each data bit at the same time. Serial communication refers to the use of a data line to transmit data bit by bit, and each bit of data occupies a fixed length of time. It only needs a few lines to exchange information between systems, especially for long-distance communication between computers and between computers and peripherals.
Chuan Xing is the abbreviation of “universal serial bus” in Chinese. USB (Universal Serial Bus) is a new PC serial communication protocol jointly formulated by Microsoft, Compaq, IBM and other companies in 1995. After the introduction of USB protocol, it has been widely supported by PC manufacturers, chip manufacturers and PC peripheral manufacturers. USB itself is also in continuous development and improvement, from the original 0.7 and 0.8 to the widely used versions 1.0, 1.1 and 2.0, and the version 3.0 that has been adopted and will be used in mass production
Data parallelism means that the computer contains a group of processing units (PES), and each processing unit stores one (or more) data elements. When the machine executes a sequential program, it can operate simultaneously corresponding to all or part of the data stored in the internal processing unit.
The so-called data parallelism refers to dividing the data into several blocks and mapping them to different processors. Each processor runs the same processing program to process the assigned data. Most parallel processing adopts this processing method, especially for problems with high computational complexity (such as hydrodynamics calculation and image processing).
In this processing mode, usually, different processors need to carry out a certain amount of communication in the calculation process. Therefore, in this parallel processing mode, it is also necessary to design a reasonable parallel processing algorithm according to the characteristics of the problem, so as to reduce the impact of communication between processors on the performance of parallel processing.
Advantages and disadvantages of serial transmission and parallel transmission:
1. Serial transmission
Advantages: less data lines are used, which can save the communication cost in long-distance communication.
Disadvantages: because only one bit of data can be transmitted at a time, the transmission speed is relatively low.
2. Parallel transmission
Advantages: because multiple data can be transmitted together, the transmission speed is very fast.
Disadvantages: the number of bits in the memory depends on how many data lines are used, so a large number of data lines are required and the cost is very high. Use occasion
1. Serial transmission:
It is especially suitable for long-distance transmission. For those man-machine switching devices not far from the computer and external devices with serial storage, such as terminals, printers, logic analyzers, disks, etc., it is also common to exchange data in serial mode. In the aspect of real-time control and management, multiple microcomputer processors are used to form a hierarchical distributed control system. The communication between CPUs is generally serial. Therefore, serial interface is a common interface in microcomputer application system.
2. Parallel transmission:
Widely used in microcomputer system, it is the most basic information exchange method in microcomputer system,
For example: microcomputer and parallel interface printer, disk drive,
For example, between components on the system board and between components on the interface circuit board.