Programmer Humor

It is a text editor from the 50s or 60s, so right off the nat you aren't getting a product you're at all familiar with. Its been a while since I cracked it open but from memory you can only view one line of code at a time. You have to specify the line of code that you want to view, the commands are esoteric, and there is no help available in the application itself. As I recall it was pretty much immediately replaced with better editors, such as og vi.

Its sort of like programming in sed. Sure, you can, but why?

From Wikipedia:

Known for its terseness, ed, compatible with teletype terminals like Teletype Model 33, gives almost no visual feedback, and has been called (by Peter H. Salus) "the most user-hostile editor ever created", even when compared to the contemporary (and notoriously complex) TECO. For example, the message that ed will produce in case of error, and when it wants to make sure the user wishes to quit without saving, is "?". It does not report the current filename or line number, or even display the results of a change to the text, unless requested. Older versions (c. 1981) did not even ask for confirmation when a quit command was issued without the user saving changes.

https://en.m.wikipedia.org/wiki/Ed_(software)