Before the VAX age, Digital had another line of large minis. Based on hardware similar to the 36-bit PDP-10 line, and software based on BBN's TENEX operating system, the 20s were in many ways never surpassed by later minis.

One of the niftiest aspects of TOPS-20, the OS, was the style of command parsing. The parsing was actually implemented in the OS as the COMND system call. The command line interpreter (shell) was called EXEC, and it made extensive use of COMND.

There are vestiges of COMND in Unix shells. When entering command arguments, you can type part of a filename and then hit escape or control-D. If you have typed a unique prefix of a filename in the local directory, the shell will complete the filename for you, or show you a list of filenames that match. COMND could do that, and a whole lot more - it was a generalized command-line parser.