Word Count

Writers Talk About Writing

Ctrl+Shift+Return: Keys to Your Computer

Your computer's keyboard has around 110 keys by which you can make your wishes known to the machine. Most of these have obvious labels: if you press the A key, the letter A appears on the screen. Some are less obvious, though — the Shift key and the mysterious Ctrl key — and in this article I'll explore why they're named what they're named.

Long before computers, many practical issues about using a machine to write had already been worked out for the typewriter. If you've never used a typewriter, you might be interested in this video that shows one in action.

In a typewriter, the paper is rolled around a platen that's part of a carriage that can move right and left. Letters are cut onto slender pieces of metal called typebars. Pressing a key on the keyboard causes the corresponding typebar to hit the paper through an inked ribbon. After the typebar hits the paper, the carriage moves to the left by one letter.

Early on, people learned to cut two letters on a single typebar. When you press a key, the lower letter strikes the paper. But you can also press a key to raise — or shift — the carriage, which causes the upper letter on the typebar to hit the paper instead. Thus the Shift key was born. (In the video, you can see the carriage being shifted for the very first letter that's typed, at 00:12.)


Typebars [Source]

When the typist reaches the end of a line, he or she uses a lever to return the carriage to the left and advance (feed) the paper up one line (00:29 in the video). When manual typewriters were eventually electrified, this somewhat laborious action was reduced to a single keystroke: the Return key.


Return key on IBM Selectric typewriter [Source]

While the typewriter was becoming a ubiquitous office tool, inventive minds in the communications industry were developing the teletypewriter (branded as Teletype, which became a generic term for it) as an improvement on the telegraph for sending electronic messages. With Teletypes, an operator far away could type a message and then send it. On the receiving end, another Teletype machine would come to life and clatter away, typing out the message.

To send signals over a wire, the Teletype machine represented each character as a numeric value. A standard set of codes developed (the ASCII chart), where 32 is a space, 46 is a period (.), 65 is the letter A, 97 is the letter a, and so on. Here's a chart of those values. (I realize that looking at charts is stultifying, but bear with me; it will become more interesting in a few moments.)

0 NUL 32 (space) 64 @ 96 `
1 SOH 33 ! 65 A 97 a
2 STX 34 " 66 B 98 b
3 ETX 35 # 67 C 99 c
4 EOT 36 $ 68 D 100 d
5 ENQ 37 % 69 E 101 e
6 ACK 38 & 70 F 102 f
7 BEL 39 ' 71 G 103 g
8 BS 40 ( 72 H 104 h
9 HT 41 ) 73 I 105 i
10 LF 42 * 74 J 106 j
11 VT 43 + 75 K 107 k
12 FF 44 , 76 L 108 l
13 CR 45 - 77 M 109 m
14 SO 46 . 78 N 110 n
15 SI 47 / 79 O 111 o
16 DLE 48 0 80 P 112 P
17 DC1 49 1 81 Q 113 Q
18 DC2 50 2 82 R 114 R
19 DC3 51 3 83 S 115 S
20 DC4 52 4 84 T 116 T
21 NAK 53 5 85 U 117 U
22 SYN 54 6 86 V 118 V
23 ETB 55 7 87 W 119 W
24 CAN 56 8 88 X 120 X
25 EM 57 9 89 Y 121 Y
26 SUB 58 : 90 Z 122 Z
27 ESC 59 ; 91 [ 123 {
28 FS 60 92 \ 124 |
29 GS 61 = 93 ] 125 }
30 RS 62 94 ^ 126 ~
31 US 63 ? 95 _ 127  


Most of the characters in the chart are ones you'd find on a typewriter. But the first 32 characters are cryptic, like BEL, HT, LF, and CR. These are known as control characters — signals that could be sent to the Teletype machine not for display, but to control how it operates. For example, STX (2) is the "start of text" character; HT (9) is "horizontal tab"; CR (13) is "carriage return"; LF (11) is "line feed"; and BEL (7) is "bell" — that is, ring the bell. When an operator originally typed the message, he or she would get to the end of a line and press a return key, just like with a typewriter. This embedded a CR character (carriage return) and a LF character (linefeed) into the message at that point. When the message was received by another Teletype machine and printed out, the control characters embedded in the message told the machine when to return the carriage and feed a new line. The message might also include other control characters for functions like inserting a tab, starting a new page (FF or form feed), and so on.

Back to our naming story. Early Teletype keyboards were comparatively primitive (they included only uppercase letters), so they included a Ctrl key that let the operator embed control characters into a message.


Teletype keyboard [Source]

The way it worked was clever: if the operator held down the Ctrl key while typing a character, the Teletype machine in effect subtracted 64 from the value of that letter. Glance again at the chart from earlier. Let's say that the operator wanted a horizontal tab (9). The operator could press Ctrl and I (73) at the same time. To create a page break/form feed (12), the operator pressed Ctrl+L. To embed a character to ring the bell, the operator used Ctrl+G.

Early Teletype machines didn't even have lowercase letters, but when those were added, the machines used a similar technique to let users specify uppercase letters — that is, to encode the action of the Shift key. Holding down the Shift key while typing a letter subtracted 32 from the value. If you look at the ASCII chart, you'll see that the values of uppercase and lowercase letters differ by 32, so that a (97) becomes A (65). (This explanation is simplified somewhat, I should note.)

When computers were developed, it was natural to adapt the encoding scheme and the keyboard of Teletype machines for input and output. Teletype machines quickly gave way to terminals, and along the way, the Return key became the Enter key, because it no longer had much to do with returning the carriage and instead was about entering (sending) a command for the computer.

These days, of course, we no longer need to encode control characters by hand. (Although we do still use the Shift key for its original purpose of creating capital letters, albeit no longer by physically shifting a carriage.)  Most programs that you use on your computer have more interesting uses for the Ctrl key than ringing the bell or embedding a tab. For example, Ctrl+i, which would produce ASCII value 9 (for the tab), is used in many Windows programs to format text using italics.

But deep under the covers, you can still find traces of the old Teletype machines. If you have a Windows computer, open Notepad and try entering some control codes — for example, press Ctrl+Shift+m to insert a carriage return, and Ctrl+Shift+i to insert a tab. And don't forget to press Ctrl+Shift+g to produce a beep, which is the modern equivalent of the typewriter's old bell.

If you can actually put your hands on an old typewriter or Teletype machine, they feel like fossils from an earlier age. Still, it's pleasing to me that when you tap away at your keyboard (even a virtual keyboard on a tablet computer), there's still a direct line, both technically and etymologically, between those keys and machines of the pre-computer era.


Rate this article:

Click here to read more articles from Word Count.

Mike Pope has been a technical writer and editor for nearly 30 years. He has worked at Microsoft and Amazon, and currently works at Tableau Software. You can read more at Mike's Web Log and Evolving English II. Click here to read more articles by Mike Pope.

Join the conversation

Comments from our users:

Monday October 15th 2012, 3:12 AM
Comment by: Sante J. Achille (L Aquila Italy)
My mom worked for Western Union many years ago. In the early 70s things were changing and telegrams were giving way to the modern teletext machines: she would write out the message which was coded onto a strip and then fed into this monster size machine ... Employees began to dwindle and on SUndays she was alone at the office so she'd bring me along sometimes - I found that place fascinating and can still recall how frustrated she'd get when the machine would reject her message because of improper formatting!

It is truly incredible how things have changes in just over 40 years - I was 8 or 9 back then.

I just realized how many generations do not know what a typewriter is and how it works - Mike You made me feel old and that's not good on a Monday morning !!

Thanks for the memories ...
Monday October 15th 2012, 5:10 AM
Comment by: Linda L. (Baton Rouge, LA)
Mike & Sante,
Just an additional note, which should make Sante feel a bit younger (and I'm betting Mike will get that warm tingle, too). I was persuaded to learn typing by my grandmother & mother -not for a future job - but so I could type my papers in college and earn some extra money, too, typing for kids who weren't as prepared as I was while attending higher education. To begin with, I was so very lucky in that the typing class in high school that year (coincidentally, my graduation year - get ready now: 1968-1969!!) was also my Home Room, so I figured out how one was assigned to machines. You were seated to the machine you happened to be placed on by the way your name fell alphabetically. You would type on that specific machine for a trimester, then move back a machine & repeat, until you had typed on all 6 machines in your row. Simply due to luck, I was placed with a Smith-Corona Manual, the only one on the row. Each row had just one manual, so each student had to type on it for one trimester. Naturally, starting off with the manual and ending with the only IBM Selectric Machine in the room during the last trimester, I ended the class with a relatively high grade.
For example, my routine that year was progressing each trimester thusly: during the 2nd semester, I typed on the most basic electric typewriter in existence. I can't even remember the name of it, but it was nothing great except that you did not have to pound it and develop finger, hand and arm muscles to type decently, as I had had to do with the Smith-Corona in September. (lol) Around the Christmas holidays, I clearly recall typing on an almost new electric navy blue Underwood that I loved. I also typed on a Royal and on a Remington, neither of which stood out in my mind. And as I already stated, I ended with a beautiful brand-new white IBM Selectric, that was all the news, as it had all the letters on a ball that flipped around so fast one couldn't watch it.
Thankfully, I became an ace typist, which not only helped me through college, but also law school, and continued to do so, as it is now, since I have always been a one-woman business. I am now the leading attorney in Alternative Dispute Resolution, especially Mediation, specializing in training others, whether attorneys, other types of doctors, or specialists in living life - Hopefully well! I drafted and lobbyied the Louisiana Civil Mediation Act in 1997 and made certain that no specific degree is required, only mediation training. while I was only in my mid-40s then, I knew so many older people who never got past high school, or perhaps not even that, that would make great mediators, and I was not about to keep them from becoming mediators.
But I am wandering. I simpy wanted to tell Mike I think his article is extremely interesting (I am an History graduate in underclass status, natch, eh?) and the point out that there are a few of us elders out here who were able to transfer our typing skills onto computers with just a few problems. I still don't know how to save documents correctly, so my machines are loaded down with documents, etc. But then, who cares? They're my computers, right?
Please keep up your fascinating writing. An article on how the PC changed the structure of handwriting skills is a good subject. Most kids today cannot read handwriting and I hear that within a generation they will have to have specially taught interpreters to read handwritrten documents. I would be very good for that job, but too old, I predict. Thanks for listening! BTW, my website is http://www.msmediator.com Check me out sometime. Always, Linda Liljedahl
Monday October 15th 2012, 4:18 PM
Comment by: Norman K. (Wellington New Zealand)
Walking down the Lane of Memory, reminded me of the most valuable course I ever took. It was a typing class in Jr. High School. That course has served me well in many areas and occupations. We would walk into a classroom filled with Remington manual typewriters. The keys were all the same black buttons with no identification marks to indicate letter, number or symbol that each key represented. We had to memorize the value of each key from a chart. For my final exam in that course, we had to type a business letter, and the only mistake I made was not double spacing after the period at the end of a sentence.
N Kabak

Do you have a comment?

Share it with the Visual Thesaurus community.

Your comments:

Sign in to post a comment!

We're sorry, you must be a subscriber to comment.

Click here to subscribe today.

Already a subscriber? Click here to login.