YMODEM

YMODEM is a protocol between two computers to transfer of files is used. YMODEM was developed by Chuck Forsberg and is the successor to the XMODEM protocol. In contrast to the XMODEM protocol, which uses 128-byte blocks for data transmission, the block size has been increased to 1 KiB , and the file name is also transmitted in the first data block . YMODEM was further developed to ZMODEM .

A variant Enhanced YMODEM was developed in 1994 by Herwig Feichtinger at Shamrock Software. It avoids gaps in the transfer by sending the following block without the check digits ( CRC ) in advance without confirmation, while the check digits are only transmitted after the confirmation for the previous block has been received. Since there is no character escaping, the achievable transfer rate is slightly higher than with ZMODEM.

Web links

• Chuck Forsberg , Ward Christensen : XMODEM / YMODEM protocol reference, A compendium of documents describing the XMODEM and YMODEM File Transfer Protocols. In: pauillac.inria.fr. June 18, 1988, accessed February 19, 2018 . 
• c't article on YMODEM and Enhanced-YMODEM in comparison ( Memento from August 19, 1999 in the Internet Archive )