An interface chip is a chip with an internal interface circuit. It has the following functions: (1) Set data register and buffer logic to adapt to the speed difference between CPU and external devices. The interface usually consists of some registers or RAM chips, so long as these chips are large enough, batch data transmission can be carried out; (2) information format conversion, such as serial and parallel conversion; (3) Be able to coordinate the types and horizontal differences between CPU and external devices in information, for example, horizontal conversion driver, digital/analog or analog/digital converter, etc. (4) differences in coordination time sequence; (5) Address decoding and selection function; (6) Set the interrupt and DMA control logic to ensure that the interrupt and DMA request signals are generated under the permission of DMA, and complete the interrupt processing and DMA transmission after the interrupt and DMA response are accepted.