Changes in the Lab

Because of the difficulties getting started in the laboratory we have made some changes:

• For the next week or two, we will have two TAs in each lab section, one speaking and one helping out.
• We have set up a new way to get the data disk - have the TA make a copy for you.
• We have shuffled around the TAs for some of the lab sections.

We have been moved into a new lab for recitations - Harriman 318. Hit `cancel' when it asks you for a password. You may use either for working in when they are open. Sorry for any inconvenience.

Keyboards

The most common input device is the keyboard, which looks very similar to a typewriter keyboard.

Special keys on computer keyboards include:

• Escape, control, alt - Like the more familiar shift key, these put the keyboard into different modes, to provide additional key combinations. Typically used for program commands. Escape is a good thing to hit when you are confused.
• Enter or Return - The return key signifies the end of the input line or paragraph.
• Numerical keypad - Supposedly useful when you are entering just numbers.
• Cursor keys - Enable you to move up, down, left, right.
• Function keys - Extra keys which may be supported by the application for application-specific functions. Often can be programming or assigned by the user.
• Insert, Delete, Home - Extra keys which may be supported by the application for standard tasks.

Status lights typically record if the keyboard is locked in shift or numeric modes.

How can one enter Chinese or Japanese, which have thousands of letters, on an English keyboard? A combination of escape keys and menus is usually used.

How can one convert a keyboard from QWERTY to Dvorak layout? This can be done via software, not hardware changes - a program takes each typed character and translates it to the desired one before passing it on.

Repetitive-stress injuries, such as carpel-tunnel syndrome, can be reduced by using wrist rests, ergonomically-designed keyboards, and taking breaks. They are a serious problem - now the most common job-related disability.

The Mouse

This pointing device has become essential with graphical user interfaces. There are two types of mice:

Optical mice which look for movement on the grid-like mouse pad. These are more precise but less flexible.

Mechanical mice which detect motion via the rubber `mouse ball' underneath. This is what you will most likely use.

Control of mouse speed, acceleration, and update rate is via software. Typically you can customize these through the operating system. These do not effect how fast you can physically move the mouse, but how physical movements correspond to screen changes.

Mice can be slow to use because one must move their hand from the keyboard. Trackballs or thumbwheels can minimize this problem.

Pen Input Devices

These permit you to enter text and select options via a stylus, such as in the Apple Newton.

Handwritting recognition is a hard problem for people, even more so than for machines. Much of our ability to read handwritting comes from context, and so requires understanding.

To make recognition easier, many systems:

• Only handle block handwriting in fixed boxes.
• Require use of a specially designed alphabet to avoid similar characters, such as 0 and O.
• Are trained on individual handwriting to maximize recognition.

Many applications do not require recognition, such as jotting notes, menus, pointing and other gestures.

Other pointing devices include trackballs and joysticks, particularly for portable computers. Also light pens and touch screens for special-purpose applications.

Scanners

Image or page scanners enable one to input a picture into the computer.

Each picture is converted into pixels, colored dot picture elements. These can take a lot of space.

Optical character recognition (OCR) converts the pixel-images to text that can be handled by normal applications. Recognition accuracy depends upon the software, the image quality, and the types of fonts used in the document.

Magnetic ink character recognition is used by banks with checks. A special font is used to make it more accurate to read, as well as special ink. Various types of `computer crimes' involve altering magnetic ink numbers.

Terminals

A terminal is a keyboard and screen device for connecting to a computer.

As microcomputer prices keep dropping, terminals have been getting smarter and smarter, so they can be used for some of the processing as well. Terminals are commonly called smart and dumb to define how much processing they are cable of.

When you are using a modem to connect your computer to the Internet, your computer is functioning as a terminal.

Special purpose terminals include ATM machines.

Sound and Voice

Microphones can be used as an input device to digitize sound.

Computers can be used to enhance and process sounds, to clarify noisy transmissions or add special effects for recordings.

Voice input systems are still under development. The problem gets harder when you seek large-vocabulary, speaker-independent, connected speech recognition systems.

The best current applications are special purpose vocabularies, like radiology.

Voice input will never completely replace the keyboard. Think about two people sharing an office!

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