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ZMODEM
Communication protocol
Purpose
file transfer protocol
Developer(s)
Chuck Forsberg
Introduction
1986; 38 years ago (1986)
Port(s)
None
Hardware
modems
ZMODEM is an inline 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. 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.
In contrast to most transfer protocols developed for bulletin board systems (BBSs), ZMODEM was not directly based on, nor compatible with, the seminal XMODEM. 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. This list includes Forsberg's own YMODEM.
ZMODEM eschewed backward compatibility in favor of producing a radically improved protocol. 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 became extremely popular on bulletin board systems (BBS) in the early 1990s, becoming a standard as widespread as XMODEM had been before it.
ZMODEM is an inline file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their...
way as Ascii85 does. When a ZMODEM program sends pre-compressed 8-bit data files over 7-bit data channels, it uses "ZMODEM Pack-7 encoding". Adobe adopted...
a further fracturing before they were re-unified by his later ZMODEM protocol. ZMODEM became very popular, but never completely replaced XMODEM in the...
1992 for developing ZMODEM. He was also the project engineer on the Tektronix 4010-series graphics terminals. The widely adopted ZMODEM uses a sliding window...
available. However, despite this protocol potentially being faster than ZMODEM it was still rarely used. This was partially due to the lack of other functionality...
features. Minicom is a menu-driven communications program. It also has an auto ZMODEM download. It now comes packaged in most major Linux distribution repositories...
high-performance system, it remains relatively obscure because it was overshadowed by ZMODEM, which had been released a year earlier and saw rapid uptake. XMODEM was...
Telnet, SSHv2, RLogin, Serial, Windows, *nix, and Mac OS X platforms, X/Y/ZMODEM and various BBS terminal emulations Rtelnet is a SOCKS client version of...
as USB flash drives Dial-up modems null modem links used XMODEM, YMODEM, ZMODEM and similar File sharing Managed file transfer Peer-to-peer file sharing...
the early 1990s. Its strengths included a fast built-in version of the Zmodem file transfer protocol, rather than needing a separate program, and a powerful...
Y-Modem, Z-Modem) is an external file transfer program which supports X/Y/ZModem transfers. It was written to break the reliance on old DOS external protocols...
dial-up-oriented protocols for transferring FidoNet traffic like EMSI or ZMODEM had to implement error-recovery. When the members of FidoNet started to...
to replace ZMODEM. It uses 32 bit CRC's on file data blocks, the same as Zmodem, and 32 bit CRC's on its information blocks where Zmodem uses 16 bit...
order, and is also found in many file transfer protocols like UUCP-g and ZMODEM as a way of improving efficiency compared to non-windowed protocols like...
emulation. Tek4010 emulation. File transfer protocols (Kermit, XMODEM, YMODEM, ZMODEM, B-PLUS and Quick-VAN). Scripts using the "Tera Term Language". 1.4 Last...
offer performance matching or beating the best file-transfer protocols like ZMODEM. In practice, many implementations only supported a single setting of 64x3...
protocols ranged from Kermit and Xmodem to Ymodem (Batch, 4K and G) and Zmodem (Batch Selections). One feature of ProTERM Mac was the C-like scripting...
DoubleDOS, and more). File transfer protocols supported by FrontDoor are Zmodem, Zmodem/CRC32, Telink, SEAlink, SEAlink Overdrive, and Xmodem/CRC. FrontDoor...
and downloading of message packets in QWK format using XMODEM, YMODEM or ZMODEM File areas Live viewing of all caller activity by the system operator Voting...
VT100, VT52 File transfer: ASCII, Kermit, XMODEM, YMODEM/YMODEM-G, and ZMODEM List of terminal emulators Official website Configuring Hyper Terminal for...
g., a QWK packet, for the user to download using, e.g., Xmodem, Ymodem, Zmodem, and then disconnect. The user reads and replies to the messages locally...
for its day. Unlike the predominant protocols of the day (XMODEM, YMODEM, ZMODEM), BiModem allowed BBS users to upload and download files at the same time...
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