The 4955A Protocol Analyzer is a high level tool for R&D and manufacturing as well as network performance analysis. It offers BASIC programming, HP-IB control, real-time clock and dual tape drives. HP has made is so easy with the 4955A, troubleshooting is straightforward with the softkey driven menus. Capability of user defined character synchronous/asynchronous, X.25, HDLC, BSC, and SDLC protocols. Data transfer rates from 50 bps to 72 kbps using internal clock, can properly frame data at higher rates using an external clock.