Input Devices


First, Why is it called a "keyboard"? There is a board, but where are the "keys"?

Much about the keyboard is based on old and often obsolete (out of date) technology. To understand, look at an old-style typewriter:

Old typewriters would use long metal "keys" with raised letters at the end in order to type characters.

Several point of everyday typing continue today because of the old technology. Take the name "keys." But a few other points continue as well.

Old typewriters used a cylinder called a "carriage." You would roll a piece of paper around it. When you hit a button on the keyboard, the metal key would jump up and hit the paper. An ink ribbon would also jump up between the key and the paper, leaving a mark of the letter you typed.

But the keys would not move--they always hit the same, one place. So instead, the paper moved. That's why they called the cylinder a "carriage"--because it carried the piece of paper.

Each time you typed a letter, the carriage would move one space. Since these machines were not smart, they could not tell the difference between a thin letter (e.g., "i," "l," or "t") and a wide letter ("m" or "w," for example). So instead, the carriage always moved the same amount. To make the typing look better, a font was created where all the characters were the same width. This is called a "monospace" font. We still see it today in fonts like "Courier."

The "shift" key is also borrowed vocabulary from the old typewriters. Each "key" on an old typewriter had an uppercase and a lowercase imprint at the end (see right). In order to change from one to the other, you would hit the "shift" key. In English, "shift" means "to move slightly." The whole set of keys would move slightly up or down, and so instead of the bottom imprint hitting the ribbon and paper, the top one would.


You may have wondered why the letters on a keyboard are arranged the way that they are. The keyboard layout that most people use is called "QWERTY," after the first six keys on the top line of letters. Many people believe that this arrangement helps you type faster.

This is probably not true. Although nobody knows the true answer, many believe that the keys were arranged to avoid key jams. A key jam is when you typed too quickly, and the metal keys would hit each other and stick together. This could ruin your document.

If this is true, then the reason we use QWERTY is to slow down your typing.

Because we no longer use metal keys, these old decisions are not necessary. So, why do people continue to use them? The answer is that it would cost too much to change! We would have to replace all the keyboards, and train everyone to use a different system.

However, because touch-screen computers are now becoming popular, you should soon be able to choose any keyboard you like. A popular alternate keyboard is called DVORAK, and is designed to allow for faster typing. Strangely, Apple's iPhone and iPad do not have software Dvorak keyboards--no one outside of Apple knows why. However, hacks can be accomplished to give you a Dvorak keyboard (see right), and likely many keyboard layouts will be possible in the future.

Today, keyboards are cheap. You can get them for under $10 / ¥1000. There are many different keyboards; in Japan, for example, you can get a U.S. keyboard, or a Japanese keyboard. Both are QWERTY, but the Japanese keyboard has a slightly different layout, and has extra keys for changing to Katakana, Hiragan, or Kanji.


The Mouse

The mouse was invented in the 1960's by Douglas EngelbartBy coincidence, my father worked at the same place as Dr. Engelbart, a research center I often visited with my father at the time., who is also known for inventing the beginnings of the GUI interfaceWe will learn about the GUI in the unit on the Operating System, and was involved in the beginnings of the Internet. The first mouse (see below) was very primitive--it was, in fact, made of wood!

The first commercially available mice looked much more like modern mice, however. They used a rubber ball at the bottom of the mouse which, when rolled, moved parts within the mouse that told the computer the cursor location. However, these rubber-ball mice were often difficult to use. Dirt would build up inside the mouse, causing it to malfunction, and the user would have to open the mouse and clean it from time to time--sometimes frequently.

The next generation of mouse is called the optical mousein the same way "optical discs" are so named, because a laser is used, which does not require cleaning. It is still not perfect, as the laser will not work on some surfaces. [Hint: if your optical mouse has trouble on the desk or surface you are using, try putting a piece of paper under it; that usually solves the problem.]

Most mice have two buttons. The left button is for an ordinary "click." It tells the computer to focus on that spot. The right button will bring up a special menu, called a pop-up menu or a contextual menu (see right)--both are names for the same one thing. It is called a "contextual" menu because the menu is different depending on what you click (the menu changes according to the context of location).

Mice also have a scroll wheel between the buttons. The scroll wheel can be used to scroll up and down a page, or for other purposes depending upon the situation. A scroll wheel can also be clicked and so used as a third button.

Today, there are a wide variety of mice. Some have many extra buttons, often used in gaming. Some are wireless, using either an infrared or a Bluetooth link. However, mice might be dying out.


The mouse is quickly being replaced by the trackpad. Originally a mouse replacement for laptop computers, trackpads are growing in popularity as their features increase.

At first, trackpads could only read the location of a single finger. When you moved your finger on the pad, the mouse moved on the screen.

Later, other features were added. For example, a trackpad could sense if you tap your finger once or twice, allowing you to use the trackpad as a button as well.

Today, trackpads are much more advanced, and use multi-touch gestureswe will learn more about multi-touch in the unit on the Operating System such as those seen in the movie at right. For example, two fingers moving up and down will scroll the page. Two fingers tapping once will open a pop-up menu. Four fingers moving up will show the Desktop, and four fingers moving left or right will switch to another program. Apple's latest laptop computers use these gestures.

Trackpads are now also available for Desktop computers as well. Apple, for example, is selling a "Magic Trackpad," a wireless device which is essentially a large trackpad to be used with a desktop computer (see left).

In fact, the function of trackpads is moving more and more in the direction of multi-touch, the same technology that tablet computers like the iPad are beginning to use.

Cameras & Microphones

Today, most computers have built-in microphones and webcams. The cameras can be used for many purposes–taking photos, capturing movies, having a video chat, or even using it as a "virtual mirror" to check out how you look. Almost all laptops have these now, and more and more, desktop computers are getting them as well.

It is also fairly easy to attach a headphone-and-mic headset, using either the audio or USB ports on the computer. Webcams also generally use USB to send a video image to the PC.