The 4952A Protocol Analyzer is a portable analyzer used for troubleshooting during installation, maintenance, and design of data communication networks and equipment. Protocols include Async, BSC, SDLC (NRZI), HDLC, X.25, SNA, DDCMP, and user-defined protocols, also tests X.21 and ISDN. Allows you to monitor and decode data transmission, test remote facilities from your location, simulate network components, and perform bit error rate tests. It can also be used as an asynchronous terminal or to install and maintain 3270 equipment, and to perform link level performance analysis.