B protocol
Open-knowledge reference entry
The B protocol, or CIS B, is a file transfer protocol developed for the CompuServe Information Service, and implemented in 1981. The protocol was later expanded in the QuickB version (which was an asynchronous version of the standard protocol) and later the enhanced B Plus version. It was a fairly advanced protocol for its era, supporting efficient transfers of files, commands and other data as well, and could be used in both directions at the same time in certain modes. These advanced features were not widely used, but could be found in a small number of client-side packages.
Since B protocol was designed only to work within the CompuServe, most third-party communications clients of the day were not compatible with it. Notable exceptions were Tera Term and Datastorm's ProComm Plus on the PC which featured the ability to listen for the Enquire command on the active communications port, and ZTerm on the Mac which allowed auto-starting transfers. This development was part of a wider trend of using external communications applications in conjunction with online services.
History
As part of a 1979 project to provide low-cost graphical terminals for the farming community, CompuServe and Tandy worked together to produce a system known as "AgVision", or sometimes "VideoTex". As part of this project, CompuServe introduced a system known as CompuServe A protocol, based on Bisync, to provide error-free transport of the commands and data. The first version was running in 1980, but it had a number of problems.
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This entry incorporates text from “B protocol” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.