What is Input? Everything we tell the computer is Input.

Transcription

1 What is Input? Everything we tell the computer is Input. Data is the raw facts given to the computer. Programs are the sets of instructions that direct the computer. Commands are special codes or key words that the user inputs to perform a task, like Input Processing Output Storage RUN "ACCOUNTS". These can be selected from a menu of commands like "Open" on the File menu. They may also be chosen by clicking on a command button. User response is the user's answer to the computer's question, such as choosing OK, YES, or NO or by typing in text, for example the name of a file. Input: Keyboard The first input device we will look at is the Keyboard. Several variations are popular and special designs are used in some companies. The keyboards shown below put the function keys in different places. The Enter and Backspace keys are different shapes and sizes. One has arrow keys while the other doesn't. It's enough to confuse a person's fingers!! The backslash key has at least 3 popular placements: at the end of the numbers row, above the Enter key, and beside the Enter key. We also have the Windows keyboards which have two extra keys. One pops up the Start Menu and the other displays the rightclick context sensitive menu. Ergonomic keyboards even have a different shape, curved to fit the natural fall of the wrists. The most often used input device is the keyboard. The layout of the keys was borrowed from the typewriter with a number of new keys added. Alphabet keys The letters of the alphabet and some punctuation marks are in these three rows. The order of the keys is called QWERTY from the order of the keys on the top row. This arrangement of the letters was inherited from the typewriter. It is not the most efficient layout. With the first typewriters, the typists had trouble with the mechanical keys jamming each other because the typists could strike the keys faster than the keys could get out of each others' way. So the letters were arranged to slow down the typists' speed. Now that electric typewriters and computer keyboards no longer have mechanical keys, a more efficient layout could be used. But so many people are familiar and skilled with the old way that it doesn't seem likely that the layout will change. Alt - The Alt key doesn't do anything by itself. But if you hold it down while pressing another key, the effect of that key may be different from usual. Exactly what will happen will depend on what program is running at the time. Arrow keys - These four keys are used to move the cursor on the screen. The up and down arrows move the cursor up or down one line. The left and right arrows move the cursor one character. Backspace - The Backspace key erases the character on the left of the cursor and moves the cursor that direction, too. Caps Lock - When the Caps Lock key is on, pressing any alphabetic key will result in an upper case (capital) letter. The number and symbol keys are not affected, however. Watch out - this is different from typewriters. Control - The Control key does nothing all by itself. It must be pressed in combination with other keys. When used in combination, the Control key changes the normal effect of a key. Exactly what will happen depends on the software in use at the time. Delete - The Delete key is used to erase the character just to the right of the cursor. Any text beyond the erased character is moved to the left. End - The End key is a navigation key. It will send the cursor to the end of the current line.

2 Enter - The Enter key is used in several ways. In word processing, it acts like the Return key on a typewriter by starting a new line. It is also used in place of a mouse click with buttons and drop-down menus. Escape - The Escape key is used to cancel actions in progress before they finish. It is also used to close certain dialog boxes. Function keys The Function keys are numbered F1, F2, F3,...F12. These are programmable keys. That is, programs can assign actions to these keys. So the same key might produce different results in different programs. Some of the function keys are becoming more standardized as to what they do. For example, F1 is most often used to access the Help file for a program. Home - The Home key is a navigation key for the cursor. It will move the cursor to the beginning of the current line. Insert - The Insert key is a toggle key. That is, repeatedly pressing it will alternate between two effects: 1. typing overtypes characters already there 2. typing inserts characters in between the characters that are already there. Some programs have an indicator on screen to show you which effect is current. But not all are as friendly. Numeric keypad When the Num Lock key is on, these keys are used to enter numbers as with an adding machine. When the Num Lock key is off, the keys act as navigation keys using the alternate markings on each key. Minus When Num Lock is on, the Minus key performs subtraction on the numbers entered. When Num Lock is off, the Minus key will type a hyphen like this -. Number/Symbol keys - On this row of keys you will see two characters, one at the top of the key and one at the bottom. The upper character is a symbol and is accessed by holding the Shift key down while pressing the key. Numbers can also be typed from the Numeric Keypad. Num Lock When Num Lock is on, the Numeric Keypad responds with numbers, as an adding machine. When Num lock is off, the Numeric Keypad responds as navigation keys using the alternate markings on the keys. Page Down - The Page Down key is a navigation key which will drop the displayed area down the page one screen's worth. It doesn't necessarily move a whole literal page at a time. That would depend on the height of a page. Page Up - The Page Up key is a navigation key which will move the cursor up the displayed area one screen's worth. It does not usually move a literal page at a time. That would depend on the height of a page. Pause - The Pause key is little used under Windows. Under DOS it is used to halt actions in progress, often so that messages on the screen can be read before they scroll off the screen. Plus - When Num Lock is on, this key performs addition. When Num Lock is off, this key prints a +. Print Screen - The Print Screen key is more useful under DOS than under Windows. Under DOS pressing the Print Screen key immediately sends the contents of the screen to the printer. Under Windows pressing the Print Screen key sends a copy of the screen to the Clipboard. You must then paste to an appropriate program and print from there. Scroll Lock - The Scroll Lock key is more useful under DOS where pressing it will stop text on the screen from scrolling off the top of the screen. This gives you time to read or print it before continuing. Shift - The Shift key is used in combination with the alphabetic keys to get upper case. With a numeric/symbol key using the Shift key will give the character at the top of the key. The Shift key can be used in combination with the Alt and Control keys to change the effects of another key.

3 Slash - When Num Lock is on, the Slash key acts as a division sign on the numbers entered. When Num lock is off, the Slash key types a /. Spacebar - The Spacebar is used to enter blank spaces in text. Sometimes it can also be used instead of a mouse click on buttons. Tab - The Tab key is used to move the cursor over to the right to a pre-set point. This is especially used in word processing to line up text vertically. Times - When Num Lock is on, the Times key acts as a multiplication sign on the numbers entered. When Num Lock is off, the Times key types a *. Input: Pointing Devices A variety of pointing devices are used to move the cursor on the screen. The most commonly used ones have two or three buttons to click for special functions. Mouse A ball underneath rolls as the mouse moves across the mouse pad. The cursor on the screen follows the motion of the mouse. Buttons on the mouse can be clicked or doubleclicked to perform tasks, like to select an icon on the screen or to open the selected document. Many recent mice have a scroll wheel as the middle button. There are new mice that don't have a ball at all. They use a laser to sense the motion of the mouse instead. High tech! Advantage: Moves cursor around the screen faster than using keystrokes. Disadvantage: Requires moving hand from keyboard to mouse and back. Repeated motion can lead to carpal tunnel syndrome Trackball Instead of moving the whole mouse around, the user rolls the trackball only, which is on the top or side. Advantage: Does not need as much desk space as a mouse. Is not as tiring since less motion is needed. Disadvantage: Requires fine control of the ball with just one finger or thumb. Repeated motions of the same muscles is tiring and can cause carpal tunnel syndrome. Glidepad Uses a touch sensitive pad for controlling cursor. The user slides finger across the pad and the cursor follows the finger movement. For clicking there are buttons, or you can tap on the pad with a finger. The glidepad is a popular alternate pointing device for laptops. Advantage: Does not need as much desk space as a mouse. Can readily be built into the keyboard. Has finer resolution. That is, to achieve the same cursor movement onscreen takes less movement of the finger on the glidepad than it does mouse movement. Can use either buttons or taps of the pad for clicking. Disadvantage: The hand tires faster than with a mouse since there is no support. Some people don't find the motion as natural as a mouse.

4 Game Devices Cursor motion controlled by vertical stick (joystick) or arrow buttons (gamepad) Advantage: A joystick gives a more natural-feeling control for motion in games, especially those where you are flying a plane or spaceship. Both have more buttons for special functions than a mouse and can combine buttons for even more actions. Disadvantage: More expensive Bulky Better ones require an additional peripheral card for best performance Touchscreen Make selection by just touching the screen. Advantage: It's natural to do - reach out and touch something. Disadvantage: It's tiring if many choices must be made. It takes a lot of screen space for each choice since fingers are bigger than cursors. Digitizers and Graphics Tablets Converts drawings, photos, etc. to digital signal. The tablets have special commands Advantage: Don't have to redraw graphics already created Disadvantage: Expensive Input: Terminals A terminal consists of a keyboard and a screen so it can be considered an input device, especially some of the specialized types. Some come as single units. Terminals are also called: Display Terminals Video Display Terminals or VDT A dumb terminal has no ability to process or store data. It is linked to minicomputer, mainframe, or super computer. The keyboard and viewing screen may be a single piece of equipment. An intelligent, smart, or programmable terminal can process or store on its own, at least to a limited extent. PCs can be used as smart terminals. A point-of-sale terminal (POS) is an example of a special purpose terminal. These have replaced the old cash registers in nearly all retail stores. They can update inventory while calculating the sale. They often have special purpose keys. For example, McDonalds has separate touchpads for each food item available. Credit card readers, fingerprint scanners, and the like are special purpose devices that send data to a computer for recognition.

5 Input: Multimedia Multimedia is a combination of sound and images with text and graphics. This would include movies, animations, music, people talking, sound effects like the roar of a crowd and smashing glass. Sound Input Recording sounds for your computer requires special equipment. Microphones can capture sounds from the air which is good for sound effects or voices. For music the best results come from using a musical instrument that is connected directly to the computer. Software can combine music recorded at different times. You could be a music group all by yourself -singing and playing all the parts! Voice Input Voice input systems are now becoming available at the local retail level. You must be careful to get the right system or you'll be very disappointed. Decide first what you want to do since a voice input program may not do all of these: Data entry - Command and control - Speaker recognition - Speech to text - Talking data into the computer when your hands and eyes are busy should certainly be more efficient. You'd have to be very careful about your pronunciation! Telling the computer what to do instead of typing commands, like saying "Save file". Be careful here, too. The dictionary of understood words does not include some of the more "forceful" ones. Security measures can require you to speak a special phrase. The computer must recognize your voice to let you in. Translating spoken words direct to type would suit some authors just fine. You'd have to watch out for those "difficult to translate" phrases like "hmmm" and "ah, well,... ummm." A number of companies are now using speech recognition in their telephone systems. For example to find out what your bank account balance is, instead of punching in your account number on the phone keypad and choosing option 3 for current balance, you could speak your account number and say "Current balance". The computer will even talk back and tell you what it thinks you said so you can make corrections. Wow! How do they change voice to data?? 1. Convert voice sound waves to digital form (digital signal processing -DSP) 2. Compare digitized voice input to stored templates 3. Check grammar rules to figure out words 4. Present unrecognized words for user to identify Types of Voice Recognition systems Speaker dependent system Speaker independent system Discrete speech recognition Continuous speech recognition Natural language The software must be trained to recognize each word by each individual user. This might take hours of talking the dictionary into the computer, to be optimistic. The software recognizes words from most speakers with no training. It uses templates. A strong accent would defeat the system, however. The speaker must pause between words for the computer to tell when a word stops. The speaker may use normal conversational flow. The speaker could say to the computer "How soon can we ship a dozen of product #25 in blue to Nashville?" - and get an answer!! Science fiction has come to life!!!

6 Video Input computer to a computer A digital camera takes still photos but records the pictures on disks or memory chips. The information contained can be uploaded for viewing. A video camera or recorder (VCR) can record data that can be uploaded to the computer with the right hardware. Though it is not digital data, you can still get good results with the right software. Both of these take huge amounts of storage. Photos make for very large files. A web cam is a tiny video camera designed especially to sit on your computer. It feeds pictures directly to the computer - no tape or film to develop. Of course you are limited by the length of the cable that connects the camera to the computer. But like any camera, it will take a picture of what you point it at! So what do people do with a web cam? They use it for video conferencing over the Internet. They show the world what's going on outside their window (weather, traffic). They take digital pictures and make movies- family, pets, snow storms, birthday parties, whatever. Input: Data Automation The first goal of data automation is to avoid mistakes in data entry by making the initial entering of the data as automatic as possible. Different situations require different methods and equipment. A second goal of data automation is to avoid having to re-enter data to perform a different task with it. For example, the old style cash register would add up your purchase and calculate the tax. The clerk entered the amounts by hand (the data entry part). Later the numbers off the store copy of the cash register tapes would have to be added up manually, or entered into a computer program (another data entry task). For an up-to-date inventory someone would have to go count all the things on the shelves (a third data entry task). With modern data automation, using bar codes on every item in the store, a computer check-out register along with a bar code scanner will calculate the sale plus transfer the information directly to the computer that does the store bookkeeping plus adjust the inventory records by subtracting the items just sold. The human errors possible at each step of data entry are now avoided. Of course, there are still ways for errors to occur, just not as many. In addition, a new feature is available with computerized cash registers - a receipt that states the name of the item bought as well as the price. General Devices Scanner- The scanner works like a copy machine. It creates a digital image of what it scanned. Scanned text cannot be edited at this point. Flat bed scanners open wide enough to allow you to lay a document or book flat on the glass surface. You can even make a scan of your hand! Bar-Code Scanner A document scanner can Hand-held or fixed devices that can read the bar codes on packages. only scan individual sheets of paper, not books or objects.

7 Credit Card Reader Swipe the credit card through the device, which reads the magnetic numbers in the magnetic strip on the card. Special types of characters read with special devices Bar Codes- Retail shops now use printed bar codes on products to track inventory and calculate the sale at the checkout counter. The US Post Office uses bar codes to sort mail, but the bars are different from those used for pricing products. Optical Marks- example - test scoring A special machine "reads" the marks. Woe to the student who takes a test with this kind of score sheet and doesn't get those bubbles colored in correctly! Magnetic Ink- Bank account # is printed in special ink with magnetic qualities which can be read by the right machine. Magnetic Strip- The back of a credit card has a metallic strip that contains magnetically encoded numbers. A credit card reader can read the numbers and transmit them to a computer to verify that the card is good. Optical Characters- There are coding systems that use letters or special characters that are especially shaped to be easy for machines to read. OCR software Optical Character Recognition: This software takes a scanned image and converts the characters in the image into computer characters. The document can now be edited with a word processor. This is a very tricky process. Documents must be carefully checked for wrong conversions. If the original print was not very crisp and clean, errors are very likely. Manually checking for proper translation is necessary. These programs are getting really good if they have a clear scan to work with.

8 Input: Data Accuracy A famous slogan in computing sums up the importance of accurate data: GIGO = Garbage In, Garbage Out Conclusions are no better than the data they are based on. Checking for Accuracy A major task for any program that accepts data is to try to guarantee the accuracy of the input. Some kinds of errors cannot be caught but many of the most common kinds of mistakes can be spotted by a well-designed program. A program should attempt to do the following: 1. test data type and format ex. 2/a/96 is not a date ex. If a phone number should have exactly 10 digits with the area code, then is not acceptable. 2. test data reasonableness ex. 231 should not be a person's age ex. A sale of $50,000 worth of chewing gum at the corner market is probably missing a decimal point somewhere! 3. test data consistency ex. A man's death date should be later than his birth date! ex. The sum of the monthly paychecks should be the same as the total pay for the year. 4. test for transcription and transposition errors ex. Typing 7754 instead of 7154 is a transcription error, typing the wrong character. ex. Typing 7754 instead of 7745 is a transposition error, interchanging two correct characters. Both are very hard to check for.

9 Name Date EMMA MS-1 Inputs Quiz 1. The most commonly used input device is the. (1 point) keyboard mouse joystick scanner 2. An advantage to a touch screen is that. (1 point) it is natural to touch things it is not as tiring as keyboard input it uses little screen space for each choice none of the above 3. GIGO stands for. (1 point) Garbage Input, Garbage Output Gigabytes In, Gigabytes out Garbage In, Garbage Out none of the above 4. The raw facts are called. (1 point) programs commands user responses data 5. VDT refers to. (1 point) vital data transfer virtual data transfer video desk terminal video display terminal 6. The keys on the keyboard which may be programmed to do special tasks are the. (1 point) arrow keys numeric keypad function keys navigation keys

10 7. A mouse, trackball, and joystick are examples of. (1 point) pointing devices pen input devices data collection devices multimedia devices 8. Which is an example of a transcription error? (1 point) 3455 instead of 3456 Simth instead of Smith 3456 instead of 3465 none of the above 9. The term multimedia refers to. (1 point) movies with sound only music only the combination of sound and images only combination of sound and images with text and graphics 10. The computer message reads "Do you really want to delete the selected file(s)?" The user clicks on the button labeled "Yes". This is an example of. (1 point) data input user response a program a command