Introduction - If you have any usage issues, please Google them yourself
XMODEM protocol is a widely used serial communication in the asynchronous file transfer protocol. Divided into standard Xmodem and 1k-Xmodem two, the data of 128 byte blocks, the blocks of bytes for 1K is 1024 bytes, and each block with a checksum and the process for error detection in the verification process. If the receiver is about a block and check with it at the sender's check and at the same time, the receiver to the sender sends a confirmation byte (ACK). Because the Xmodem needs are recognized for each block, which will lead to the decline in performance, especially the long delay situations, this agreement is less efficient.
In addition to Xmodem, and Ymodem, Zmodem protocol. Their agreement is similar to Xmodem, the difference is that Ymodem allows batch file transmission, high efficiency; Zmodem is improved by Xmodem, it only needs to damage other block retransmission, the correct block does not need to send a confirmation byte. Reduces the amount of communication.