LAST UPDATE: 11/26/06

Under  REconstruction!

This is a rewrite of my first prototype presentation of I/O.
I will improve this, with better graphics, to make it more suitable for independent learning.
Blinking text designates things that I need to work on; the material is not wrong, but can be improved.
(Don't worry, I don't like blinking text, either, so there will not be any in the finished product!)

LEARNING MODULE V
INPUT/OUTPUT HARDWARE

        The hardware interface between the human user and computer system is the input/output (usually called I/O) hardware, but (as always) hardware is "driven" by software, so when we talk about an I/O device, remember there is an associated "device driver". (This was discussed in section 3.1.A.b of Learning Module II, Software and illustrated in Figure I/O-1.) Obviously the easier it is to get data into and out of a computer, the more useful the computer is. This has resulted in the development of ergonomics, the "science" of user-friendly interfaces. (The ultimate is the radically new brain implant input chip that is being experimented with; see Figure I/O-4!)  Most "real world" data is analog, i.e. it consists of continuous signals like sounds, pictures, voltage, etc. However, computers can only process digital data (discrete signals); therefore, input usually involves analog to digital conversion (A/D hardware) and output reverses the process using D/A converters.   Both input and output can be subclassified as either direct (to/from I/O devices) or indirect (to/from secondary storage). (See Figure I/O-2.)  Output can also be divided into another two kinds: hard copy output (paper, microfilm, etc.) provides a permanent record while soft copy output (visual, audio, tactile, or action) is transient. Action output facilitates control of electromechanical devices, e.g. robotics. The sophisticated interaction of all types of inputs and outputs is spawning the exciting world of "virtual reality"! Two outstanding Web sites for comparisons of I/O devices (and all other hardware) are PRICE WATCH, www.pricewatch.com/,  and C|NET's computers.com. The text has separate chapters for Input and Output, but, because there is a synergistic overlap of these two types of devices, I find it more informative to cover them together in a complimentary presentation.

The goals of this Learning Module are to help the student:

1. learn the basic functional organization of input and output devices within a computer system.
2. utilize the similarity between input and output to better understand I/O in general.
3. understand the symbiotic relationship between input and output, especially in complex systems like VR.
4. classify input devices as either interactive or source data automation in order to more easily remember their similarities and differences.
5. classify output devices as either hardcopy, soft copy, or action in order to more easily remember their similarities and differences.

TPQ 1: Rewrite the preceding objectives in terms of personal accomplishments to be attained after finishing the study of this learning module.

The sequence of presentations in this learning module is as follows.  You can click on any link to jump directly to that section.

1. DIRECT I/O VS. INDIRECT I/O
2. DIRECT INPUT VIA HUMAN INPUT DEVICES
3. AUTOMATED INPUT VIA SDA DEVICES
4. VISUAL OUTPUT DEVICES (SOFT COPY)
5. AUDIO OUTPUT DEVICES (SOFT  COPY)
6. HARD COPY (PRINT AND FILM) DEVICES
7. ACTION OUTPUT: COMPUTER CONTROL OF ELECTRICAL DEVICES
8. SUMMARY {NEED TO WRITE THIS!}

SAQ: A device driver could be described as a "__________ interface".
 

1.  DIRECT I/O VS INDIRECT I/O (See Figure. I/O-2):

        From the most general viewpoint input to a computer has two distinct categories, that which is read directly from the input device and that which is read from secondary storage (called indirect input).  This distinction was introduced in Figure O-1 of LM I where the blue parallelogram represents direct input and the yellow store parallelogram involves indirect input.  However, some direct input (that involving humans) requires direct output, e.g. typing at a keyboard would be impossible if you couldn't see what you type on the computer monitor, which is an output device.  Thus we have three basic subdivision of input/output, human Input/Output, source data automation, and indirect input/output.

1. Direct I/Occurs two ways:
1. Human input is called transaction Processing which involves on-line, interactive input.  Because it is interactive this also involves output via a computer monitor, speakers, etc.
2. Source Data Automation (SDA) automates the original input by off-line reading of data directly from the source (document, sensor, etc.). Usually involves A/D conversion.  Because it does not require human interaction this does not, of necessity, involve output.
2. Indirect I/O is automatic loading from computer files from ___________(1), avoiding the necessity of human involvement in the I/0 process. It most common form is batch processing, automated input via a set order of "jobs" (programs or different executions of the same program). Computer jobs are not executed when they are entered; they are delayed until they system has time to run them. (This old-fashioned type of processing is obsolete, but it is still used for low priority jobs that can be run overnight or at the weekend.)

Direct Input (and Output) are discussed in this learning module, but indirect I/O rightfully belongs in LM IV on secondary storage.

2. DIRECT INPUT VIA HUMAN INPUT DEVICES:

2.1 Keyboard:

1. Types of General-purpose Terminals:
1. Dumb terminals (virtually obsolete) can only input to a separate CPU.
2. Smart terminals have their own memory and editing capability.
3. Intelligent terminals are smart terminals with their own CPU.
4. Workstations are microprocessor based __________(2) terminals. Microcomputers, when they are networked, can be used as workstations.
5. Portable micros can be used for remote input for later input into larger systems.
2. There are no standard keyboards; however typical keyboards have typewriter layouts (called "QWERTY").  The Dvorak keyboard was designed specifically to improve typing efficiency, but has yet to overcome the human's tendency to avoid "unnecessary" change!
3. Enhanced keyboards usually contain numeric keypads, special function keys, cursor control keys, et cetera; these are used in virtually all computers.

1. Cursor control devices are used to place the cursor (a highlighted screen location indicating where the next action will occur), select menu items, and control the computer by "clicking buttons" on the screen. If these are built into the computer they are called "integrated pointing devices".
1. _________(3): a standard device of GUI interfaces. New versions are optical (have no moving parts) and wireless.  An LED records a reflected light which senses motion over a flat surface.
2. trackballs: like an "upside-down mouse"; it has the advantage of being stationary.
3. joysticks: are hand-held stick that pivots about one end indicating 360 degree directions; they are most commonly used as control devices in computer games ans simulations; see below.
4. trackpoint or pointing stick: a miniature joystick that responds to the touch of a single finger.  (See Illustration  andText equivalent, Fig. 5-10.)
5. trackpads: a touch sensitive surface that translates finger motion into cursor motion.
2. Pen input devices are based on screens that sense the location of a special pen that is connected to the terminal.
1. Light pens either detect the monitor's light or emit light that can be picked up by a specially designed monitor.
2. Styluses are pens with electronic points heads which activate pixels on the monitor, usually a LCD display.  Handwriting recognition software translates alphanumerics to digitized equivalents; normally these need to be "trained" to recognize an individual's carefully printed letters, numbers, and symbols.  These have been rather primitive, but significant advances have been made recently. They are the the primary input device of hand-held PDAs (______________________(4)) and PIMs (______________________(5)) (See the Learning Module, THE CENTRAL PROCESSING UNIT AND PRIMARY MEMORY, section 1.1C.) State -of-the-art readers reportedly are very accurate.
3. Digitizing tablets are similar to light pens or styluses except one draws on a tablet rather than the screen.
3. Touchscreen allows selection of menu items displayed on a monitor by touching them.

1. Gamer's Input devices (game controlers) include joysticks, steering wheels, and other devices that simulate real world equipment.  (See examples of PC game controllers. which come in a surprising variety of innovative devices.   {UNFINISHED}
1. (See Joysticks & Gamepads at Tiger Direct)
2. A point-of-sale (POS) terminal is a computerized improvement of a cash register that can process credit/debit cards, record and track customer orders, manage inventory, communicate with other devices on a network.   Modern POS terminals typically are Web-enabled, allowing remote operation and invetory tracking.   Typically, a POS terminal has specialized software and dedicated I/O devices customized for a particular sales environment. 
3. An ATM (automatic teller machine) is an online computerized terminal where secure financial transactions can be processed without human interaction.  ATM users typically access their credit card accounts in order to make withdrawals, but some ATMs also allow bank transactions such as deposits, money transfers, bill payments, and even purchases.   (Be careful not to confuse this ATM acronym with that for  "asynchronous transfer mode", discussed in LM VI.)
4. <>Innovative input devices for physically challenged users utilize a wide range of technologies including voice recognition, gesture recognition, large key, on-screen keyboards (touchscreen), head-mounted optical pointers, etc.  (See video from ZDTV.)

3.1 Scanners :

1. Image Scanners (Gray-scale or color) digitize the pictures (which are analog data). (See  How scannders work and Text, types of scanners,  Fig. 5-30.) The resulting bitmapped images (Each pixel has a collection of bits that define its color; see section 4.1.A, below.) can be easily modified by graphics programs.  The resolution of bitmapped images is measured in dpi (dots per inch).
2. Facsimile transmission (Fax) machines convert scanned images into signals that can be transmitted over telephone lines. Fax boards may be plugged into the expansion slots of a micro computer enabling it to send and receive fax images via a modem.
3. Bar code readers decode a series of bars of different widths and spaces. These are widely used in point-of-sale (POS) systems.

Optical Mark Recognition (OMR) equipment can distinguish filled-in spaces (optical marks) on special source documents, e.g. the ____________(6) sheets on which COSC 100 preassessment and assessment answers are entered.
4. Optical Character Recognition (OCR): Software associated with image scanners allows the computer to read printed or typewritten text.
5. RFID (Radio Frequency Identification) Readers input data emitted via radio signals from electronic tags that are used to identify a tagged object, e.g. animals, store items, identification cards, etc. The tags (also called "transponders") function as electronic "labels" consisting of an RFID chip attached to an antenna. Tags may be battery-powered or derive their power from the RF waves coming from the reader. RFID are an improvement on bar codes in that they do not require line of sight in order to be read. 
   

1. MICR devices read prespecified characters printed with a special magnetic ink.
2. Used primarily on Bank Checks.

1. Sensors allow direct input of analog signals (e.g. temperature, light, sound, etc.) that are converted to ____________(7) data, via A/D converters, for computer processing.
2. Sensors are essential in Robotics, automated data acquisition, manufacture, security, etc.

1. Digitized Audio Signals:
1. Audio (____________(8)) signals can be converted to digital signals by analog to digital converters, processed by a computer and converted back with digital to analog converters. This allows computer manipulation of music (See MIDI, below), speech or any recordable sounds.
2. Synthetic audio signals can be created by the computer.
3. Musical Instrument Digital Interface (MIDI) devices allow the input and output to any musical instrument capable of electrical I/O. The music, once digitized in the computer's memory can be processed by musical software giving an incredible opportunities for creativity and innovation.  (See illustration and Text equivalent, Fig. 5-19.)
2. Voice Input and Speech recognition:
1. Microphones convert spoken words (analog signals) to digital signals that can be processed by a computer. (Words are "digitized".)
2. Digitized words are compared to "voice templates" stored in memory.
1. Customizable devices can be "trained" to recognize an individual's speech.
2. Current systems are still rather primitive and have limited vocabularies; however, rapid improvements are being reported.
3. If a word is recognized it is processed; if not then the user has to ask for recognizable input.

1. Digital cameras: Digital cameras have optics like regular photographic cameras; however, they record the single analog images electronically (rather than on photographic film) in digital form. The analog images are converted to digital images by an analog-to-digital-converter (ADC); these images are stored in the camera's RAM ((____________(9), which like that in a computer is volatile). The images can be displayed immediately or stored on a secondary storage medium and processed, later, by image processing software.  (See How Digital Cameras Work and Text equivalent, Fig 5-25.)
2. Digital Video cameras: These are digital cameras which can store sequences of digital images on magnetic tape and play them back as "movies". (See How Video Cameras Work  and Text, Figs. 5-27 and 5-28.) They are similar to camcorders, but camcorders store their images as analog data. (See the next section.)  Digital Video cameras are essential features of videoconferencing where remote computers can actually control a remote camera and remote users can share applications and collaborate on "whiteboards".  This is covered in more detail, under "teleconferencing", in LM VII, section 2.2.A.)
3. Analog image converters: Photographs taken with regular cameras and videos recorded with camcorders store their images as analog data. There are special kinds of hardware that can take these images (scanning photographs or converting camcorder tapes) and convert them to digital images which, like any other digital image, can be processed by computers.

1. Biometrics is the science and technology of measuring and statistically analyzing biological data.
   
1. In information technology, biometrics usually refers to technologies for measuring and analyzing human body characteristics such as fingerprints, eye retinas and irises, voice patterns, facial patterns, and hand measurements, especially for authenticating someone.
2. Biometric identifiers recognize physiological (physical) characteristics of a user, e.g. fingerprints, facial dimensions, voice, etc.

4.1 Cathode-Ray Tube Displays (CRTs):

1. CRTs use raster scan technology to portray images as bitmapped graphics on a phosphorescent screen.
1. Process: an electron beam sweeps horizontally across the screen sequentially stimulating phosphorescent pixels (screen picture elements).
2. Monochrome monitors: one color images on a one color background, e.g. old mainframe monitors.  These are now virtually obsolete in PCs.
3. Color monitors: a triad of red, green, and blue phosphor dots are stimulated in varying degrees to produce a wide range of colors.
1. Composite video monitors (like TVs) have one electron gun. NTSC (National Television Standards Committee) monitors are compatible with video signals in the U.S.A. Such systems can easily process video signals and superimpose digital (computer) output and video output. However, composite video has lower resolutions than . . .
2. RGB monitors use three electron beams which give a higher resolution display.  Virtually all modern monitors are RGB.
4. Imaging Types:
1. Bitmapped CRTs allow individual ____________(10) to be addressed thereby producing greater screen control; this is the origin of WYSIWYG applications that can incorporate high resolution graphics (e.g. all modern PC monitors).
2. Old fashioned character-addressable CRTs only address or manipulate groups of pixels (that form alphanumerics) and are inherently non-WYSIWYG and have crude graphics (e.g. mainframe and minicomputer monitors).
5. Resolution indicates the ability to show detail, the more pixels per inch the higher the resolution; however, in color monitors, more colors constrain the resolution. There are several standards for traditional monitors including:
1. Early Standards:
1. CGA 320x200 pixels, 4 colors
2. VGA 640x480 pixels, 4 colors (or 256 colors at 320x200)
3. XGA 1024x768 pixels, 4 colors; (max.) 256 - 64K colors
2. Current and high-end monitors, are distinguished by prefixes to "XGA"; they range from SXGA (1280x1024) to QSXGA (2560 by 2048).
3. (See Wikipedia's comparison of monitor resolutions which shows comparative display sizes.)
6. Paging is the movement of the screen image one screen at a time.
7. Scrolling is the movement of the screen image one line at a time.
8. Windowing allows different outputs to be displayed on different parts of the screen.
2. Vector Graphics screens create images by the electron gun tracing between specified points on the screen rather than scanning every row; they are limited to special types of graphics monitors.

1. They eliminate flicker and radiation and minimize size problems of CRTs.
2. The most popular type is the Liquid Crystal Display (LCD) which has a thin layer of liquid crystal molecules, divided into small squares forming pixels, that are held by two glass sheets. When power is applied to a square it turns opaque. LCDs used to be limited in size, brightness and clarity, but current technology has significantly improved.
3. In a plasma display  each screen pixel is illuminated by a tiny bit of plasma or charged gas, sandwiched between glass plates, which glows when voltage is applied.   Plasma displays typically larger and brighter than LCD displays, but have less contrast and are more expensive.
4. See the excellent comparison of CRT, LCD, and Plasma displays at Flat Panel Technology from Crutchfield.com.
   

SAQ: What does "virtual" mean?

1. VR headsets contains 3D imaging technology combined with stereo audio and motion sensing that allows one to go "inside" and move through a responsive, simulated 3D environment .
2. Currently available as part of gaming and entertainment environments, VR also has a wide range of professional applications

5.1 Voice-Output (Speech Synthesis) Devices (Soft copy):

1. Speech synthesizers transform ____________(11) computer signals into voice (____________(12)) output.
2. In the word analysis method entire digitized words from the computer's vocabulary are combined, under computer control, into digitized sentences and then converted to analog output. This requires a huge amount of memory.
3. In the constructive synthesis method the basic elements of speech, called "phonemes" (only 40 in the English language) to construct speech output governed by timing, pitch and inflection controls. This has minimal memory requirements.

6. HARDCOPY (PRINT AND FILM) DEVICES:

6.1 Printers can be classified three ways:

1. Image formation (measured in dpi (____________(13)):
1. Full character alphanumerics (no graphics) each have a separate symbol on a ball, daisy wheels, thimble, band, belt or chain mechanism.
2. Dot-matrix alphanumerics and graphics are formed by patterns of dots from a single print head .
3. Raster scan images (alphanumerics/graphics), e.g. laser printers, are like copiers.
2. Image transfer:
1. Impact printers transfer images by the print head striking a ribbon like a typewriter.
2. Nonimpact printers transfer images by heat (electrothermal and thermal-transfer printers), electrostatic charge (laser printers), or by "drawing" with ink jets.
3. Number of characters printed at one time, measured in ppm (pages per minute):
1. Serial (bidirectional) printers print one alphanumeric or graphics pixel at a time.
2. Chain printers transfer one line of alphanumerics or pixels at a time.
3. Page printers (laser printers) utilize a combination of raster scan and xerographic technologies to produce one whole page at a time.

1. Flatbed plotters have a drawing instrument (pen, ink-jet, electrostatic head, or heater element) that moves both horizontally and vertically, under the control of input voltages, over a flat piece of stationary paper.
2. Drum plotters have a drawing pen that moves vertically while the paper, on a drum, rotates under it.

1. COM outputs a microphotography copy on microfilm or microfiche.
2. This expensive medium will probably be replaced by laser disks.

1. Film recorders copy computer generated graphics directly onto film media.
2. Streaming image sequences can be used to generate ____________(14).

1. Automation:
1. Tedious, error prone, and dangerous jobs are ideal for computer automation.
2. Automated data acquisition can free laboratory workers from tedious tasks.
3. Automated buildings will have far reaching consequences for human living and working.
2. Robotics: Robots are mechanical devices, controlled by computers, that can move and/or do work. (NOTE: They rarely resemble humans except in the movies and on TV!)
1. The simplest robots only do work under program control.
2. The most complex robots have sensors that allow them to see, hear, and feel and to respond to the feedback from these sensors. Computer vision is an active field of research that is still far from the capability of the human eye.
3. Numerical control produce mechanical parts from numeric specifications.
3. Process Control is the computer control of mechanical operations that insure a specified precision an accuracy in the product being produced.
4. VR: Tactical (sense of touch) output is a form of action output. Currently this is very limited, but some applications such as chest pads that simulate punches to the body, joysticks that give servo feedback simulating the feel of flight, steering wheels which jump and vibrate to simulate the feel of a car, etc. are currently for sale.

1. Virtual Reality (VR) software create immersible, computer-generated environments that use input devices such as the data glove (a glove wired to sense hand motion and finger movement; see an example.) and output to a VR helmet (displaying 3D graphics and audio) and perhaps even or haptic (tactile) devices that allow the user to interact with a complete simulated environment.  Actually a "full body glove" would be required for the ultimate virtual reality experience (a la fanciful  movies like The Lawnmower Man (Steven King), The Matrix (and it's sequels), etc.)   In any case, virtual reality involves a sophisticated interaction of both input and output devices that involves all human activities (input) senses (output). (See section 4.3, below.)
1. The VR environment can be:
1. a simulation of the real world, for example, flight simulators, combat training, virtual tours, etc. or
   
2. a fanciful world such computer adventure games, arcade VR experiences, etc.
2. Touch, smell, and taste:  "Researchers have set their eyes on the sense of touch, smell, and taste as they attempt to usher in a world of total perceptual communications. Sensual interaction over the Internet is primarily limited to seeing and hearing, but researchers across Japan are working to allow more sensory feedback for users of communications technology. For example, a tactile mechanism would enable surgical robots to transmit tactile sensations to a remote surgeon who performs a procedure while controlling surgical instruments on a video monitor. A pair of forceps, a scissor-like device developed by researchers at Keio University, is designed to allow the surgeon to "feel" the tissue and organs she is touching. "This promises a huge jump in the safety of robotic surgery," says professor Kohei Onishi of Keio. Meanwhile, the Tsuji Academy cooking-school chain has developed a device that can produce artificial smells like beef stew and curry using a process that is similar to the way in which printer ink is released from a cartridge. And Intelligent Sensor Technology is already bringing to market a taste sensing system that uses technology developed by Kyushu University's Kiyoshi Toko."    Click Here to View Full Article.
3. Outstanding References:
1. See the interesting simulation demos at ForgeFX.
2. VR in the Critical History of Computer Graphics and Animation.
3. VR gear, including touch, from The Science Channel, Discoveries this Week, 11/3/06.
   
2. Augmented Reality, unlike VR, deals with the real world; it adds graphics, sounds, haptics, and smell to the natural world as it exists, thus "augmenting" (or adding to) reality.  Current applications include weapons aiming headsets which superimpose informative graphics on the user's field of view and allow weapon's targeting to track head movements.  See the nice description of augmented reality in How Stuff Works.   Augmented Reality video clip, from The Science Channel, "Beyond Tomorrow" (#1 on DVD).

FIGURE I/0-1: PC I/O DEVICES AND DRIVERS

 
 
 
 
 
 
 
 

FIGURE I/O-4: INPUT FROM A BRAIN IMPLANT!
(Cumberland Times ?/10/98)

See the "Brain Gate" (chips implanted in the brain) video clip from "Beyond Tomorrow", The Science Channel.