hi, In 1990s Tektronix produced digital video X terminal and introduced X server software based on VxWorks v5 (Windriver). Later they introduced a new line of terminals, at some point a company called NCD bought the Tektronix X11-terminals division and started to produce their own line, called NCD-terminals with a software called "NCD-bridge"
Anyway, both the 200-series and the 400-series of the Tektronix X11 terminals boot from a directory on a server via NFS or TFTP, either way, you need to create a directory for the terminal to boot from, and install a number of files. These files are provided as "Tektronix XpressWare version 8.0 (or later)". The 200-series can bootstrap from v7 ( one of the member of my team owns an original CD), but the 200-series needs the v8 or later (we don't have). Unofficially, you might look for NCD, the Company who bought the X-terminals division from Tektronix; they had (note the past tense) some software in the form of patches, accessible by anonymous ftp. There aren't any complete releases, but there were archives which contains much that is useful to be found in the ftp, in particular patches containing bits of version 8.1 of XpressWare; enough to form the basis of a working installation. Unfortunately, the archive is gone, no more available. Let me know if you have the software or if you know where/how to find it, otherwise, X11-terminals like X400 can't be functional. Thanks