#Putty or syncterm series#

If the packet is received correctly, the receiver sends an ACK message and the sender then starts sending the next packet. After the payload comes a checksum or cyclic redundancy check (CRC) that can be used to determine if the payload was received correctly.

The main portion of the packet, the payload, is a certain number of bytes from the file being sent.

#Putty or syncterm series#

Generally, file transfer protocols break down a file into a series of packets, and then send them one-at-a-time to the receiver. ZMODEM became extremely popular on bulletin board systems (BBS) in the early 1990s, becoming a standard as widespread as XMODEM had been before it.

It performed as well or better than any of the high-performance varieties of XMODEM, did so over links that previously didn't work at all, like X.25, or had poor performance, like Telebit modems, and included useful features found in few or no other protocols. ZMODEM eschewed backward compatibility in favor of producing a radically improved protocol. This list includes Forsberg's own YMODEM. Many variants of XMODEM had been developed in order to address one or more of its shortcomings, and most remained backward compatible and would successfully complete transfers with 'classic' XMODEM implementations. In contrast to most transfer protocols developed for bulletin board systems (BBSs), ZMODEM was not directly based on, nor compatible with, the seminal XMODEM. In addition to dramatically improved performance compared to older protocols, ZMODEM offered restartable transfers, auto-start by the sender, an expanded 32-bit CRC, and control character quoting supporting 8-bit clean transfers, allowing it to be used on networks that would not pass control characters. ZMODEM is a file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their X.25 network. ( May 2018) ( Learn how and when to remove this template message) Please help to improve this article by introducing more precise citations. This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations.