Chapter 5, Input

Discovering Computers 2004

Topics

	Storage devices will be categorized separately from input and output devices.
	Input: Any data or instructions entered into the computer via an input device or read from a storage device. Data: Anything entered into a computer that is not a program, command, or user response. Even programs, commands, and user responses are considered data to some pieces of system software. The boundary becomes fuzzy. program: Sequence of instructions for the computer to follow automatically. command: Direction to the operating system to take specific actions, or parameters governing how the operating system works. user response: Can be data or commands.
	Input Devices History: Joseph-Marie Jacquard's punched cards, developed for controlling silk weaving machines http://www.maxmon.com/1800ad.htm , was the forerunner of the IBM 80 column punched card. Here is an 80-column punched card. Keyboard:  Keyboard arrangement Qwerty Problem: Keys of a mechanical typewriter would jam if more than one key is pushed almost at the same time. Urban Legend: Designed to slow a typist.  A fast typist would spend a significant amount of time clearing jams.  By slowing the typist, the number of jams reduced, increasing the effective speed of the typist. Truth: The QWERTY keyboard was an improvement upon an earlier arrangement, and it was designed to increase speed by reducing jams. For a fascinating historical review, see http://home.earthlink.net/~dcrehr/whyqwert.html  Dvorak (Start | Settings | Control Panel | Keyboard | Language | Properties | United States - Dvorak)  See also Marcus Brooks "Introducing the Dvorak Keyboard",  http://www.mwbrooks.com/dvorak/ (08 Jul 2000), viewed on 20 Feb 2002. Designed to allow a typist of American English to be faster. Output to an electronic device rather than mechanical device means mechanical jams are no longer an issue. Keys 110 Typing keyboard Numeric keypad Special keys: Control, Escape, Alternate, Windows Function keys: F1= Help Toggle keys: Insert/ overlay, Caps Lock, Num Lock Arrow keys Interrupt keys: Print Scrn/ SysRq, Pause/ Break Internet keys: connect, email, search, volume, mute, many for selecting Keyboard connections Wired, remote Keyboard shape: Ergonomics designed to sell natural, wave, ball or melon shaped split keyboard wrist rest Language selection: Keyboard has switches; assignment of characters to switches is arbitrary and under software control. Windows system disk has a library of fonts and key assignments. Can download a visual keyboard from Microsoft for free from http://officeupdate.microsoft.com/2000/downloadDetails/viskeyboard.htm   Pointing device: A device that is used to identify objects by pointing. Pointer: A small symbol used to identify an object of intention. mouse:  5 button with scroll wheel motion sensing mechanical: rolling ball rotates pair of counting wheels, @ $10.  OK for home use. optical: @ $35 - $50,  Much easier to clean.  Elementary school classrooms should use this rather than the mechanical mouse.  Cleaning time is reduced to 2 seconds per day per mouse rather than 2 minutes per day per mouse. People doing high quality image editing prefer the precision of control by the optical mouse over the mechanical mouse. gyroscopic: gyroscope stabilized accelerometers, drifts, gyro too small. transmission: wired, radio link, IR link touchpad: Use the top side of the fingernail for better precision control. Track ball; marble mouse. @ $35 - $50.  Good for lack of room to roll a mouse around people who cannot easily hold a mouse still while pressing a button long fingers lack of fine motor control pointing stick simulation and game controls: joy stick, wheel touch screen: accommodating fat fingers in GUI design reduces the possible resolution. Avoiding carpal tunnel syndrome:  Get out of the well-lit, heated, air conditioned office.  Milk cows by hand, bale hay, plow field, clean the barn. Pen: pressure: graphics tablet electrical contact: stylus light sensing: light pen Electronic signatures: Used in retail stores for credit card authorization.  This is not the same as digital signatures (an encrypted ID) that are legal for contracting under the law passed by Congress and signed by Clinton.
	Public Policy and Ergonomics Ergonomics  Science and Engineering of the human interface of equipment for the purpose of functionality, safety, productivity, occupational health Prominent prior to World War II in design of military equipment Prominent issue today in Workman's Compensation law suits Tax-based Workman's Compensation for Repetitive Stress Syndrome is out of control.  People want a free, risk-free life at someone else's expense. Good engineering for convenience and comfort is OK.  Just because something is OK does not mean it warrants being supported by public taxes or mandated by law. Why should farmers, who have much more physically stressful and dangerous jobs without regular working hours, having a hard time making ends meet, and get no workman's compensation benefits, be taxed to compensate office workers who have a comparatively safe, comfortable environment, and do not have to do arduous physical labor? Private or company-sponsored insurance is a reasonable alternative.
	Audio Speech recognition:  speaker-dependent, speaker-adaptive, speaker-independent Speaker-dependent software requires several hours of training. Speaker-adaptive software is trained during use.  The user must identify mistakes made by the software. Speaker-independent is very computationally intense.  It assumes no accent (so it is pre-trained). continuous, word-spotting, and discrete speech Continuous speech: determining word boundaries is computationally difficult. Word-spotting software allows the speaker to use continuous speech, but the software only listens for and recognizes specific words or phrases. Discrete speech requires pauses of about 1/4-second between words. mathematically difficult problem What combination is most effective? Voice Response System: reservation systems, phone agent help or information system Many voices (must be speaker-independent) Limited vocabulary requirement Dictation One voice: (can be speaker-dependent) can "train" the system Can train the user Unlimited vocabulary requirement: phonemes Good if you must produce written text, but you cannot type or you type very slowly. Still a requirement for correcting the produced text.  Do not expect perfection! Dictation to a stenographer is still much faster and more reliable, but requires 2 people instead of one. Audio input devices and file formats microphone, MIDI, audio CD player, other devices File formats: There are many formats. Babeland. They vary according to sampling and compression schemes used, and header and trailer data that give parameters for the signal portion of the file. sampled A/D (.wav), compressed (.au, .mp3)
	Handheld and Mobile Computers As an input device to a desktop computer IR port USB cable Input devices to a handheld and mobile computer, PDAs: This is the limiting factor desktop computer download stylus or pen handwriting recognition software or on-screen keyboard image selection (slow) attach full size keyboard digital camera
	Digital Cameras Issues: data capture, resolution, sensitivity, spectrum, storage capacity, temporary/ reusable storage, data transfer, data format. Nice layman's information for NOV 1999: Kelvin Goh, "Comdex: Cameras offer higher resolution, capacity"  (November 19, 1999) http://europe.cnn.com/TECH/computing/9911/19/comdex.cameras.idg/index.html  Traditional cameras store an analog signal using chemical means (film). Image capture: 3 megapixel CCD (Charged Coupled Device). Store digital signal rather than analog.   Technology not mature yet, still changing.  Even the physical method for digital storage is still being developed.  There is not an industry-wide standard for doing this yet, nor should there be.  We are still at the innovation stage. The goals are: high density storage; reliable and inexpensive manufacturing; ease of customer use; quality comparable to film, cost per image less than film.  High hardware cost is an acceptable one-time expense. Twice in the last 2 years, IBM has made remarkable progress in increasing magnetic storage density, which will benefit the digital camera market.  128 MB flash memory cards also are producing high capacity storage that record images satisfactory for consumer use equal to 35 mm film (requiring 2 MB per image). Issue: obsolescence, lack of support.  Common problem with any rapidly developing technology.  Buy all your accessories, software, and extra storage media when you first buy your camera. Types of camera: Point and shoot, field camera, studio camera Resolution: Some sample data below from a brief web search. To get good reviews, consult IEEE articles before a purchase of a quality camera. Pixel: picture element. This is a single point in an electronic image. dpi: dots per inch. This is the number of pixels per linear inch on a display. You need to know the display size before this can be interpreted as a measure of image quality. Optical resolution: the true standard for capture and recording quality. Number of points per unit area digitized Angular resolution and distortion of optics Enhanced or Interpolated resolution: uses mathematical methods to guess at pixel values that occur at locations between recorded values.  This refers to resolution of the displayed image presented to the viewer, not the resolution of the recorded image.  This cannot produce detail that was not present in the original image. 1152 x 864 ($ 119, Kodak, 14 SEP 01), 1280 x 960 ($ 148, PhotoSmart, 14 SEP 01), 1600 x 1200, 1792 x 1200 (considered normal resolution for a good digital camera), 2272 x 1704 ($ 635, Sony, 14 SEP 01), 24-bit encoding.  14 SEP 2001 prices from http://www.dcresource.com/reviews/cameraList.php3 On the high end, the resolution is an order of magnitude higher.  Science and Industry digital camera: QImaging http://www.qimaging.com/product_info.html A single picture is worth 1000 words, but takes as much room as 1000 pages of text. Choose carefully.  Download time consideration.
	Video Video input:   video capture card, huge storage demand Format standards: Moving Picture Experts Group (MPEG) digital video camera: records video as a digital signal, connect to parallel or USB port, does not require a video capture card. huge storage requirements.  3 minute video raw data can require 1GB of storage. compression: Wavelet transform video codec (coder, decoder): hardware compression, much faster than with software video digitizer: to digitize a frame of video from an analog video recording PC Video Cameras capture still and moving images good for video teleconferencing used for security monitoring When used with the Web, some call it a Web cam [buzz...] When used to transmit moving images continuously, it is called a streaming cam [buzz...] Digital watermark: the text is wrong.  A digital watermark is an image superimposed onto another image to provide evidence that the image is authentic.  This usually involves encryption of the watermark image to prevent it from being altered.  It does not prevent copying the rendered image from multiple documents by a criminal, and then extracting the watermark portion of an image and re-encrypting it using a new key to fool people via redirection to the criminal's web site. Issue: How do you provide self-authentication, perhaps through encryption, while preserving the methods and data used to do the authentication? Videoconferencing: A visual and audio meeting between people using computers, usually separated geographically, over a network. Whiteboard, PC cameras, microphone, speakers, computer, communications
	Scanners and readers Optical scanner Reflection or projection: light source Sensor: charge coupled device Produces bitmap Each dot: color, shade of gray Resolution measured in dots per inch (column, row)  150 dpi for text 300 dpi for draft math 600-800 dpi for good math and images 1200 dpi for professional publishing in 1994 resolution, file size tradeoff image processing: capture, store, analyze, display, print, manipulate image holder: flatbed, pen, sheet-fed, drum Optical Character Recognition: software that analyzes a bitmap image to extract text that can be edited with a word processor. No longer requires special OCR fonts, like OCR-A Routinely now capture and encode a wide variety of fonts. Still need to correct 5+ error groups per page of scanned text.  It is not a reliable automatic process. For already typed documents, reduces standard document entry from 30 minutes per page proofread down to 15-20 minutes per page after corrections are made. Does not convert math and use of other special symbols well, if at all. Satisfactory for standard alphabet and business correspondence. Adobe Capture, used with Adobe Acrobat.  There are others. Optical readers:  optical mark recognition: ScanTron, for testing bar code scanner Bar code pattern of parallel lines and spaces of different widths Variety of codes. See pictures on page 5.29. UPC - Universal Product Code, labels in the grocery store: The Cat (Radio Shack) POSTNET - for zip codes Codabar - library, blood bank Magnetic Ink Character Recognition, MICR: banking industry Predates modern OCR International standard Huge economic investment by banking industry in this technology ID Card Scanners: Encoded/ Encrypted data: See military ID card. handwriting recognition
	Data collection devices Inventory input: barcode scanner with keyboard. wireless transmission to store computer, or store data for later download. Sensor, transducer, signal conditioning, processing, parameter extraction, storage device
	Helping the disabled help themselves to be re-enabled Keyguard, head-mounted pointer, foot key-pad, voice synthesizer On-screen keyboard Gesture recognition: sign language, lip reading, facial movements, eye movement Brain implant to generate signals.