B protocol
(重定向自Quick B)
CompuServe's B protocol, also known as CIS B, is a file transfer protocol developed for their commercial online service (CIS) 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.