(1) Classified by universality, there are universal interfaces and specialized interfaces. A universal interface is a standard interface that can be used by multiple peripherals, while a dedicated interface is specifically designed for a certain type of peripheral or application.
(2) According to the data transmission method between peripherals and interfaces, it can be divided into serial interfaces and parallel interfaces. The host and interface are responsible for data transmission through the internal system bus, and data is always transmitted in parallel. In parallel interfaces, the width of data transmitted between peripherals and interfaces is one byte (or word) of all bits, and the amount of information transmitted at once is large, but the number of data lines will increase with the increase of data width. In a serial interface, data between peripherals and interfaces is transmitted bit by bit in a serial manner, with a small amount of information transmitted at once, but only requiring one data line. So, parallel interfaces are suitable for transmission between close range devices and hosts; Serial interfaces are more suitable for use in remote terminals and computer networks where devices are far away from the host.
(3) According to the control method of accessing peripherals by the host, it can be divided into program query interfaces, program interrupt interfaces, DMA interfaces, and more complex channel controllers.
(4) According to the flexibility of functions, it can be divided into programmable interfaces and non programmable interfaces. The function of programmable interfaces is variable, and through programming, the same interface can perform multiple different functions; Non programmable interfaces can only use hard wired logic to implement fixed functions.
(5) According to the different types of input/output signals, it can be divided into digital interfaces and analog interfaces. The input/output of digital interfaces are all digital signals, and the parallel and serial interfaces listed above are all digital interfaces. Analog/digital converters and digital/analog converters that contain analog signals belong to analog interfaces.
