> 
> And following up myself, I might add, that if all you've got is ed
> (allen, not the editor), you don't even need the man pages, and ed
> (the editor) will most likely be more than enough...
> 

Actually 'ed', the editor, is a subset of the ':' mode of 'vi', also
known as 'ex'.

I think that Bill Joy started with a version of 'ed' which had been
enhanced and renamed 'ex' (EXtended ?), to which he added the visual mode.

He quickly found that each type of terminal used different sequences
for such things as positioning the cursor, deleting a line, and clearing
the entire screen.  So he wrote the 'termbap' library.

The AT&T folks did not like the serial search in /etc/termcap for each
terminal so they wrote 'terminfo' and added capabilities.

To return to the original subject, hardly anyone likes 'ed' for
interactive use but it is often called from shell scripts because it is
small and does not output anything except when told to or when displaying
its ONE error message, '?'.  That's it.  Just '?'.