Where Did Vim Come From?

12 Jul 2020 | categories: blog

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For a lot of people vim is the editor they use every single day, for some people they only interact with it when using git because it’s the default editor on their system. For me I used to be in the latter group until last year when I made the plunge and now I sit firmly in the former.

Vim is an interesting piece of software with a steep learning curve, but what I find most interesting about it is its family tree. Vim didn’t just fall out of Bram Moolenaar’s head one sunny afternoon, it was an iteration on an already existing piece of software.

I find the history interesting enough that I would like to walk through how this ubiquitous text editor came to be, so get your coat and let’s head on back to the 1960s.

unix development

Back in 1969 the development of the Unix operating system had begun at Bell Labs, and amongst those developing the system was an engineer called Ken Thompson. Ken was, in my eyes, some sort of wizard. Over his life time he has created or had a hand in creating many useful things such as grep and the Go.

By Peter Hamer - Ken Thompson (sitting) and Dennis Ritchie at PDP-11
Uploaded by Magnus Manske, CC BY-SA 2.0, Link

As you can see in the image above there were no CRT displays kicking around, they had to do all of their programming using teletype printers, this meant any input or output would be line by line. Ken Thompson was used to using a line editor from university called qed which stands for Quick Editor. He had reimplemented qed for a few systems since then, in fact these versions of his are notable due to the fact they were the first to implement regular expressions, but for Unix he decided to write his own version of qed which he called ed.

line editors

ed is still found on computers today, it is known as the “standard editor”, so I would like to briefly depart from the history lesson to give you an overview look at how ed works. Not only is this handy to know but I want to show you just how involved editing text is with a line editor.

Δ ed
i
hi there
.
w my_file
9
q
Δ cat my_file
hi there

Starting at the top I have entered the command ed which starts with a blank buffer, nice and simple so far. ed is a modal editor so on line two when I enter the application I am sitting in “command mode”, I enter the i command to enter “insert mode”, this means anything I type after this will be entered into my buffer on the line that I am currently at. I type the string “hi there” followed by a single dot, this dot tells ed I have finished editing and would like to return to command mode.

I then issue the command w followed by a file name “my_file”, ed obliges and saves the buffer to a file then tells me how many characters that were written (9 which includes the newline). Then I issue the q command to exit ed and I’m back in the shell where I print out the contents of my file.

ed’s other tricks

Being able to write text to a file is fine, but you know when you’re editing code you want to be able to jump around, make edits, move text, all of that good stuff.

For this section I have a file called food with this text in it.

dear god I love pizza
is there anything more joyous than melted cheese
circular food clearly came from the heavens
pizza is the bomb

I’ll also split the input/output into smaller sections to talk about it as we go, it’s easier to follow that way.

viewing lines

Δ ed food
133
P

I start ed by giving it the name of the file I want to edit and it loads it into a buffer for me then tells me there’s 133 characters. I use the P command to turn on the prompt which adds an asterisk so you can see which lines are command prompts and which are output from ed.

*.=
4

When you load up a buffer you are placed at the final line and your current line can be referred to by a dot, so any command that expects a line number will also accept a dot (the last line is represented by $). The = command prints out the line number so I run .= to show you our current position is at the end of the buffer.

*1
dear god I love pizza
*3
circular food clearly came from the heavens
*1,3p
dear god I love pizza
is there anything more joyous than melted cheese
circular food clearly came from the heavens

Entering a number and hitting enter will move you to that line and print it because p (print) is the default command, so if no command is specified then it’ll assume p. I show you lines 1 and 3, then I print a range of lines with the m,n syntax. m being the first line through to n inclusive.

*g/pizza/p
dear god I love pizza
pizza is the bomb

The g/pizza/p command is made up of g, /pizza/, and p. The g command means globally do something (i.e. for each line), then the text between the forward slashes is a regular expression, and finally p prints. In other words for each line, if you see the word pizza in it I would like to print the line.

Does this functionality seem familiar? If we shorten “regular expression” down to “re” then you get g/re/p. This was so handy Ken Thompson pulled it out of ed and made it a dedicated command for searching for text in files and called it grep.

*q
Δ

And for the sake of completion I exit ed with the q command.

some edits

To wrap up this detour I’ll quickly show some edits.

Δ ed food
133
P
*n
4       pizza is the bomb

As usual we fire up ed and it graciously tells us the character count, then whack it in prompt mode to help differentiate the input/output. n will print out the line with the line number and it defaults to .n which is your current line.

*a
too much probably isn't a great idea though
.

a means “append”, so we add a new line to the end of the buffer and as usual a dot on its own means we are finished inputting our text.

*1,$s/pizza/pie/g
*1,$p
dear god I love pie
is there anything more joyous than melted cheese
circular food clearly came from the heavens
pie is the bomb
too much probably isn't a great idea though

Then the next line we make use of the incredibly useful s command which is used for substitutions. 1,$s/pizza/pie/g means from line 1 to the end of the buffer ($) I want to substitute the regular expression pizza with the text pie. I’ve tacked on a g at the end which again means global but, because s works on single lines, g in this context means change every instance of pizza found on the line, otherwise only the first occurrence of “pizza” would be affected.

fuck me that was effort

Yes, that is a lot of work. And if you were using a teletype printer like Ken was you’d have to wait until the printer spat out the output. Slow, laborious, not to mention the syntax is quite dense, but it worked. Imagine writing an entire operating system using it.

On that note, you would do well reading the ed manual or at least knowing where to find it because who knows perhaps ed will be the only thing you have on a server some day, it could save your bacon.

There is a lot more to ed, I barely scratched the surface there with my brief overview. I’m sure if you saw someone who understood it inside out (perhaps someone who wrote ed, like Ken Thompson) you might say you’d need to be some sort of God to understand it at all.

em

Someone who certainly felt the same way about ed was a guy called George Coulouris, in the autumn of 1975 he extended ed enabling his new software to make use of these fancy new video terminals that the university he was attending had recently acquired. em would allow you to see parts of the file you were editing.

He named his creation em which is short for ed for mortals. Apparently Ken Thompson had visited George’s university once when George was developing em and Ken had this to say:

“yeah, I’ve seen editors like that, but I don’t feel a need for them, I don’t want to see the state of the file when I’m editing”.

Alright Ken you mentalist.

ex

In 1976 George Coulouris spent the summer as a visitor in the Computer Science department at Berkeley where he brought his em software with him, after all they had teletype terminals so why not. During this trip he met a man called Bill Joy and George showed him em, and Bill was certainly impressed by it.

The only problem with em was that it would be very CPU intensive, especially if it was loaded onto a mainframe that would be used by multiple users. Bill took a copy of George’s em before George left Berkeley and began working with a chap called Chuck Haley on the source code, trying to improve it to make it less resource intensive. This led to the creation of ex which stands for EXtended.

Version 1.1 of ex made it onto Berkeley Software Distribution of Unix (BSD) in 1978.

tool legacy

Bill Joy used a computer called the ADM-A3 to write the code for ex, and the computer had a profound affect on it. The reason being that it had a particular keyboard layout which drove many of the decisions he made when it came to deciding which symbols/keys to use for commands.

By Chris Jacobs - Own work, CC BY-SA 3.0, Link

Pictures are lovely, the one above is nice, but what I’m interested in showing you is the keyboard layout, so let’s see a diagram.

By No machine-readable author provided. StuartBrady assumed (based on copyright claims). - No machine-readable source provided. Own work assumed (based on copyright claims)., CC BY-SA 3.0, Link

There are a few things that are different here than our modern keyboard layout so I’ll bullet point them:

• The escape key is where you would usually find the tab key
• The control key is where you would usually find the caps lock
• The : symbol doesn’t need you to press shift
• The arrow keys are on the home row
• The ~ symbol is on the HOME key.

The first four will interest people who use vim while the last one is just interesting in itself, the computer was so influential during that time that it’s the reason we can write ~/file_name as a substitute for $HOME/file_name today.

vi

Now, ex is itself a line editor but it did have a command you could enter to go into a visual mode, and that was :visual or :vi for short. They found over time that people were entering ex and the first thing they were doing was entering :vi to switch to visual mode. So in ex 2.0, which was released on BSD in 1979, vi was created as a hard link to ex which put a user directly into visual mode. In reality vi and ex aren’t two different things, vi is ex.

Bill Joy worked as the lead developer on the project up until version 2.7, and he continued to make occasional contributions to the project up until version 3.5 in 1980.

Mary Ann Horton took the baton and assumed responsibility for vi adding support for things like arrow keys, macros, and improving the performance. vi was improved upon over the coming years, but because it was initially built upon ed it meant ex and vi could not be distributed without an AT&T source license (due to ed being developed at Bell Labs). People wanted free alternatives and as a result clones of vi began popping up, in 1987 a dude called Tim Thompson wrote a clone of vi for the Atari ST which he called ST Editor for VI Enthusiasts, or STEVIE for short.

Vim

Tim Thompson posted the C source code for this editor on a newsgroup in 1987 and it was ported to Unix, OS/2, and Amiga by someone called Tony Andrews. And it is here where Braam Moolenaar got the source code of this STEVIE port for his Amiga which he started tinkering with to create his own editor. Braam released the first public version of his creation in 1991 which he called “Vim”, this stood for “Vi IMatation” but he later changed to “Vi IMproved” in 1993.

what a bunch of nerds

As is always the case with computers and software there is a rich history full of complete dorks building things because they love what they do. No one told Ken Thompson to create ed, no one put a gun to George Coulouris’s head and told him to write em, no one forced Bill Joy to improve it and create ex, I dare say Tim Thompson created STEVIE because he wanted to, was Tony Andrews coerced into making those ports of STEVIE? Hard to say but I’m not putting money on it. Then we come to Braam Moolenaar who, like everyone else, just created vim because he wanted to.

Imagine what state the world would be in if people didn’t create things for free and give them away. Imagine what kind of world we would have if there wasn’t an abundance of dorks everywhere. Long live dorks.