Xmodem is an error-correcting protocol for modem that was created in 1978 by Ward Christensen and became a de facto standard. Modems that agree on using the Xmodem protocol send data in 128-byte blocks. If a block is received successfully, a positive (ACK) acknowledgement is returned. If an error is detected, a negative (NAK) acknowledgement is returned and the block is resent. Xmodem uses the checksum method of error checking.
By submitting your personal information, you agree that TechTarget and its partners may contact you regarding relevant content, products and special offers.
See modem error-correcting protocols for a comparison with other error-correcting protocols.
Dig Deeper on LANs (Local Area Networks)