And if you know ed, you can use almost anything close to it.   I hated DOS's edlin but if I was stuck it was close enough.

Although the famous ? error from the original version was annoying.

Truly, I still suggest that any modern user, take Rob and Brian's book and until you can do the exercises without think about it, you really are not yet comfortable with UNIX.  I even recommend at least read and looking at the chapter on nroff.

Clem