1 1 Computer technology Computer technology: Summary / Abstract / Overview 2 The following presents a general, basic overview of Automation Microcomputers Character encoding schemes Output Scanners Digital cameras Computer-peripheral interfaces Computer ergonomics
2 3 Computer technology Automation Information processing: an introduction 4 For an introduction to the broad subject of information processing and computer-supported information processing in particular, see encyclopedia articles and textbooks.
3 Information processing: acronyms 5 In this domain many acronyms are used. Their meaning is explained for instance on the Internet, available free of charge:»http://foldoc.doc.ic.ac.uk/foldoc/ in English»http://www.internetwoordenboek.kennisnet.nl/ in Dutch/Nederlands»http://www.pcwebopedia.com/ in English Information systems: the fundamental units 6 Hardware - Physical components of a system Software - Instruction sequences for a system Data - Static representations of system content Procedures Tasks and activities to be performed by people in conjunction with a system People - Stakeholders of a system
4 Computer technology: product segments 7 Large-scale systems Midrange systems Workstations Personal computers Peripherals Software Services Maintenance Data communications Computer technology: phases of automation 8 Planning / aims / purpose / goals Software Hardware Planning / aims / purpose / goals Hardware Software
5 Components and costs of automation: initial costs 9 System planning and acquisition Personnel + consulting + visits of other users + participation to conferences +... Personnel costs during initial training + teacher(s) +... Software Hardware Installation; cables Components and costs of automation: recurring costs 10 Continuous training of personnel concerning automation Support and services Maintenance of hardware Software updates Insurance...
6 General evaluation criteria for computer products 11 History and quality 1. of the producer? 2. of the dealer? Time required for delivery? Technical support, help, assistance»by phone; by fax; by ; (via a BBS); via WWW; via a user group; on site?»during installation? in the future? during the weekend? Warranty: how long? In the case of hardware:»repair work and required parts free of charge?»on-site or only carry-in? Computer technology: some information sources 12 Journals (on microcomputers)»pc Magazine (USA...)»PC World (USA, UK...) Usenet newsgroups»comp.* World-Wide Web, for instance with dictionaries: in the section on Computers and Internet, Information and Documentation, Computing Dictionaries
7 13 Computer technology Microcomputers Hardware components: the computer 14 Main computer system: CPU, power supply, ports... Video/graphics card/board Additional RAM Disk drives and controllers Video display monitor...
8 15 Hardware components: peripherals Local area network hardware Printer Modem Power supply in the computer room + backup Floppy disks Cables Mouse Suitable furniture Computers and their layer architecture The computer in layers like onion skins: Hardware BIOS Operating system & Drivers Applications
9 ?? Question?? 17 What is is the main advantage offered by by a system architecture like a layered onion skin? The microcomputer market shares 18 Intel-processor - based (HP-Compaq, Dell, Toshiba...) Apple
10 Intel microprocessors: evolution DX 80386SX 80386SL 80486DX 80486SX 80486SL Pentium; Pentium + MMX Pentium II = PII Pentium III = PIII; Celeron Pentium 4... Example Intel microprocessors: growing number of transistors Pentium
11 Example Intel microprocessors: increasing power (in MIPS) Pentium ?? Question?? 22 Summarize the evolution of of the information processing capacity of of computers. What is is the consequence for the future of of computer applications?
12 Computer memory chips: ROM versus RAM 23 Types of memory chips: ROM = Read-Only Memory (used in the BIOS, expansion cards,...) RAM = Random Access Memory Flash-ROM = Flash-Memory = upgradeable memory, is not really ROM but RAM **-- Computer memory chips: types of RAM 24 DRAM = Dynamic RAM, slow but cheap (used in main computer memory) SRAM = Static RAM, fast but expensive (used for instance in memory caches) VRAM = Video RAM (used in video cards)...
13 **--!! Task - Assignment!! 25 List and discuss criteria for the evaluation of of a microcomputer. **-- How to buy/choose/evaluate/select a computer? 26 See for instance:»http://buy.com/»http://computers.cnet.com/»http://www.zdnet.com/computershopper/ For reviews/evaluations/opinions on all kinds of products:»http://www.epinions.com/
14 **--!! Task - Assignment!! 27 Read Chapter 1 about Computer hardware in in Part Part one: one: Fundamental aspects of of computing and and related technologies, in in William Saffady, Introduction to to automation for for librarians, Chicago :: ALA, Computer technology Character encoding schemes
15 Character encoding schemes: some important standards 29 01? EBCDIC ( 8-bit) ASCII 7-bit 2**7 = 128 ISO bit 2**8 = 2**7 x 2 = 256 Unicode 16-bit 2**16 = 256*256 = Character encoding schemes: ASCII and extensions 30 ASCII = American Standard Code for Information Interchange: 128 codes, each of 7 bits, that represent the uppercase and lowercase letters of the alphabet, numbers, and some standard keyboard characters and control codes Many systems implement an 8-bit, extended ASCII code, which allows 2x128 = 256 characters. However, there is no unique standard for the upper 128 codes, so that the upper 128 characters vary from system to system.
16 Character encoding schemes: Unicode bits per character. Provides room for 2**16 = characters. Universal: designed to meet the needs of the international community Uniform: fixed-length codes for efficiency and simplicity of programming **--?? Question?? 32 How many different characters can be be supported by by unicode?
17 33 Computer technology Output Computer graphics boards and displays: scheme 34 Program Program for Windows Windows Driver software Driver for Windows Computer graphics board Computer display
18 ?? Question?? 35 Which types of of computer display do do you know? Computer displays: various types 36 CRT = Cathode Ray Tube Traditional displays based on the same principle as television and video monitors Gas-Plasma display Thin display screen used in some older portable computers, also new way to build flat video and computer monitors, thin and light enough to hang on any wall LCD = Liquid Crystal Display A translucent glass panel using a matrix of tiny liquid crystal displays, most likely technology to replace CRT!
19 **--?? Question?? 37 Which evaluation criteria do do you know for displays? Computer displays: some desirable properties 38 High contrast High brightness Sharp display; small dot size Large size of the display screen Small physical size Low heat generation Low power consumption Low distortion of images Lack of ghosting in the case of LCD displays Low emission of radiation that may harm the user High maximum refresh rate Adjustable height
20 Computer displays: comparison of various types 39 Display type More than 1 resolution setting Response time Heat generation CRT LCD yes no + from - to + High Low Computer displays: ergonomics 40
21 Computer graphics boards and displays: resolution 41 Number of picture elements ( = pixels)»horizontal»vertical Colour depth (= number of colours or gray levels on the display chosen from a palette with a larger number of colours) Example: Classical VGA: 640 horizontal x 480 vertical x 256 colours Computer graphics boards and displays: desirable properties 42 High spatial resolution High number of colours displayable at the same time High refresh rate = no flicker High speed of display
22 !! Task - Assignment - Exercise!! 43 Check the refresh rate and the resolution capacity of of your computer system: -- --spatial resolution -- --number of of simultaneous colours Check that the present optional screen settings are appropriate for your work. Computer graphics boards: factors determining their quality 44 Amount of video RAM Speed of the video microprocessor Software ( drivers ) for the communication between programs and the display...
23 Example Computer graphics boards for microcomputers with Intel processors 45 Abbreviated name MDA HGC CGA PGA EGA MCGA VGA 8514/A TARGA SVGA XGA XGA-2... Name Monochrome Display Adapter Hercules Graphics Card Color / Graphics Adapter Professional Graphics Adapter Enhanced Graphics Adapter Multicolor Graphics Array Video Graphics Array 8514/A TARGA Super VGA Extended Graphics Array Extended Graphics Array-2... Origin / Creator IBM Hercules IBM IBM IBM IBM IBM IBM AT&T consortium IBM IBM... Year Computer graphics boards and displays: evolution 46 Many variations confusing subject compatibility problems Fast evolution to higher quality
24 **-- How to buy/choose/evaluate/select a computer display? 47 See for instance:»http://buy.com/»http://reviews.cnet.com/ For reviews/evaluations/opinions on all kinds of products:»http://www.epinions.com/ Printer types 48 Type price noise text quality speed Dot matrix low high + + Laser / LED high low Inkjet low low
25 Print technologies: dot matrix 49 Produce characters by striking pins against an ink ribbon to print closely spaced dots. - Disadvantages:»- noise»- no high quality output Print technologies: laser printers: introduction Introduced by Hewlett Packard in 1984 as an alternative to dot matrix -printers (ink jet printers were not yet available).
26 **-- Print technologies: laser printers: process By means of a laser and a photoconductive drum, an electrostatic image of the page is created. Toner on the drum is attracted by a negatively charged paper. Paper and toner are heated to stabilize the image (fusing). Print technologies: laser printers: comparison with other printers + Advantages: + higher quality black text documents + higher print speed for black text documents - Disadvantage : - ozone is an inherent byproduct of printing process (though ozone filters are used).
27 Print technologies: ink jet: introduction No physical contact with page-surface: jet of ink is projected out of printhead onto surface to be printed ( non-impact printer ). More drops per character => slower printer speed. **-- Print technologies: ink jets: process The printhead consists of hair fine nozzles. In most systems, heat is used to fire ink through the nozzles onto the paper: 1. ink is heated to create a bubble 2. pressure forces it to burst and hit the paper 3. resulting vacuum draws new ink from the reservoir
28 **-- Print technologies: ink jets: process scheme Print technologies: ink jets: comparison with other printers - Disadvantages: - low capacity of cartridges as compared with laser - paper for photograph quality prints is expensive - costs per page is higher than with laser printers - ink may smudge immediately after printing + Advantages: + hardware is relatively cheap + produces high quality color photo prints
29 **--!! Task - Assignment!! 57 Read Fischetti, Mark Ink-jet printing. Scientific American, December 2002, pp **--!! Task - Assignment!! 58 Read Jendro, Oliver Inkjet technology: The magic of of inkjets. PCWorld (England), March 2005, pp
30 **-- Print technologies: solid ink printers 59 Developed in the beginning of the 1990s by Tektronix. Marketed almost exclusively by Tektronix. They use solid wax ink sticks instead of toner. **--?? Question?? 60 What is is a page description language (PDL)? Which advantages offers a page description language (such as as PostScript)?
31 **-- Page description language: introduction 61 a particular Page Description Language **-- Page description language interpreter in printers: advantages 62 + Calculates character bitmaps, thus saving space on the hard disk of the computer. + Frees the microcomputer CPU from bitmap calculations. + The interpreter adapts the output from the computer to the capabilities of the printer! + Page description languages are independent of + the type of CPU in the computer + computer operating system
32 **-- Page description language interpreter in printers: disadvantages 63 - Extra costs are due to the required CPU, extra RAM and interpreter software in the printer. - The calculations by the interpreter slow down the printer. **--?? Question?? 64 Why can we we say that a printer with a PDL is is also a computer?
33 ?? Question?? 65 Compare the spatial resolution of of common displays and printers (for black characters only). Resolution of displays and printers for documents with black characters only 66 In the simple case of only black characters on a plain background: Common displays:»1000 pixels per 30 cm = about 30 dots / cm Common printers:»600 dpi = about 600 dots per 3 cm = about 200 dots / cm (+ variations in the size of dots to increase the resolution)
34 Colour ranges supported by video displays and printers 67 Range of colours supported by various processes = gamut Visible colour gamut Video display gamut Inkjet colour photo printer gamut 68 Computer technology Output of characters
35 ?? Question?? 69 Where in in the system that you use are the characters (fonts) stored that will be be printed: on on the computer or or on on the printer? **-- Printing characters: overview of various methods (1) 70 Using the fixed (bitmap) fonts built into the printer, or downloaded to the printer or added to the printer as an additional cassette»limited number of fonts»limited variations in size and shape of characters»fast»computer is free from tasks related to printing»costs of a program interpreter in the printer are avoided
36 **-- Output of characters using bitmap fonts in the printer 71 Microcomputer User Application software Display fonts Display driver Printer driver Display Fonts / Typefaces Print-out **-- Printing characters: overview of various methods (2) 72 Using fixed=bitmap fonts on the computer system which sends these to the printer»as many fonts available as put on the computer»limited variations in size and shape of characters»fast»font bitmaps take a lot of disk space on the computer»costs of the program interpreter in the printer are avoided
37 **-- Output of characters using bitmap fonts in the computer 73 Microcomputer User Application software Display fonts Printer fonts Display driver Printer driver Display Print-out **-- Printing characters: overview of various methods (3) 74 Using the scaleable=vectorised fonts in the printer + page description language program interpreter in the printer which creates the character bitmaps (e.g. PS)»Limited number of fonts»many variations in size and shape of characters»fast»computer is free from tasks related to printing»costs of program interpreter in the printer
38 **-- Output of characters using scaleable fonts in the printer 75 Microcomputer User Application software Display fonts Display driver Printer driver Display scaleable fonts / typefaces Processing of characters to bitmaps Print-out **-- Printing characters: overview of various methods (4) 76 Using scaleable=vectorised fonts on the computer (e.g. TrueType fonts) which creates the character bitmaps and sends these to the printer»many fonts»many variations in size and shape of characters»slow»fonts take some disk space on the computer»costs of program interpreter in the printer are avoided
39 **-- Output of characters using TrueType processed on the computer only 77 Microcomputer User Microsoft Windows application software Microsoft Windows TrueType display and printer fonts Display driver Printer driver Processing of characters to bitmaps Display Print-out **-- Printing characters: overview of various methods (5) 78 Using scaleable=vectorised fonts on the computer (e.g. Adobe, TrueType) + page description language program interpreter in the printer which creates the character bitmaps (e.g. PS)»Many fonts»many variations in size and shape of characters»fonts take some disk space on the computer»fast»costs of program interpreter in the printer
40 **-- Output of characters using TrueType processed on computer + printer 79 Microcomputer User Display Microsoft Windows application software Microsoft Windows TrueType display and printer fonts Display driver Printer driver Processing of characters to bitmaps for display Interpreter Print-out?? Question?? 80 Which advantages are offered by by storing the fonts centrally on on the hard disk, available for the operating system?
41 ?? Question?? 81 What is is WYSIWYG? **--?? Question?? 82 List and discuss criteria for the evaluation of of a printer.
42 **-- How to buy/choose/evaluate/select a printer? 83 See for instance:»http://buy.com/»http://computers.cnet.com/»http://www.zdnet.com/computershopper/ For reviews/evaluations/opinions on all kinds of products:»http://www.epinions.com/ **--?? Question?? 84 Which method do do YOU use to to print from your computer?
43 85 Computer technology Scanners?? Question?? 86 Which applications do do you know of of scanners?
44 Scanners: applications 87 DTP = desk-top publishing (scanning pictures or insertion in your documents) FAX document imaging, for archives and for document transmission using computer networks OCR = optical character recognition bar code scanning scanning of signatures for on-line comparison with images stored in the central computer...?? Question?? 88 Which types of of scanners do do you know?
45 Scanners: various types 89 Flatbed scanners! Hand-held scanners Sheet feeding scanners Drum scanners Film scanners Photo CD system Digital cameras Barcode scanners **--!! Task - Assignment!! 90 To To learn the basics of of scanning you can read Day, Jerry B. B. Super Scanning techniques. The Hewlett-Packard guide to to black & white imaging. New York :: Random House, How scanning works Selecting an an image type.
46 !! Task - Assignment!! 91 Read How scanners work by by Jeff Tyson **--?? Question?? 92 How can a fax system be be built from a computer + a scanner +...? Which hardware and software is is required?
47 !! Task - Assignment - Exercise!! 93 Scan Scan a simple pure pure text text document at at low low and and higher spatial resolution (50 (50 dpi, dpi, dpi, dpi, dpi, dpi, dpi ) and and find find out out which resolution offers appropriate readability. Note Note the the file file format the the size size of of each each file, file, and and print the the files files at at double size. size.?? Question?? 94 A scan yields a set set of of descriptions of of picture elements on on a computer. In In most cases each description takes bit bit in in RAM, when a colour picture is is displayed. Why 24?
48 Scanners: number of bits per pixel 95 bits per pixel = 3*8 30 = 3*10 36 = 3*12... Result line art = black or white 16 levels of gray 256 levels of gray (or 256 different colours) 256 levels for each of the 3 primary colours levels for each of the 3 primary colours levels for each of the 3 primary colours... **--?? Question?? 96 When a printed page is is scanned at at 300 dpi and 256 gray levels, then how large is is the resulting raw computer file? (Show how you estimate this.) How can this size be be reduced?
49 **--?? Question?? **3 256**3 are are many many colours colours in in comparison with with the the limited limited number of of colours colours available to to a painter painter for for instance. Nevertheless, it it can can be be difficult to to achieve achieve an an acceptable quality quality by by scanning a work work of of art art for for instance. Explain Explain this this paradox.?? Question?? 98 Scanning: How much bigger is is the resulting file, when the spatial resolution is is increased from 150 to to 300 dots per inch, without compression?
50 ?? Question?? 99 If If the number of of gray levels in in scanning is is increased from 2 (black or or white) to to 256, then how much bigger becomes the resulting computer file? Explain.?? Question?? 100 Explain that scanning involves a trade-off = a compromise between quality of of the result and file size = required storage capacity = time needed for a transfer through Internet.
51 ?? Question?? 101 What do do you think about the following: It It is is very simple: If If you will print at at 600 dpi, then you must scan at at 600 dpi. **-- Scanners: how to handle gray levels 102 Reality: can be seen as an infinite number of gray levels scanning and dithering to half tone Scanned image: limited number of gray levels halftone image Typical monochrome 300 or 600 dpi printer: output = half tone image: black dot printed (or not) on white paper, simulating gray levels
52 **-- Scanners: the TWAIN standard 103 TWAIN = a standard in image acquisition Developed by Hewlett Packard, Kodak, Aldus, Logitech, Caere Advantages: +Producers of an image acquisition device must create and deliver only one device driver file for their device. +Developers of application software need only make their program TWAIN compliant to be able to access and control any TWAIN devices. **-- Scanners: the TWAIN standard scheme 104 User Application software 1 (TWAIN compliant) Application software 2 (TWAIN compliant) Device driver (TWAIN compliant) (provided by scanner producer) Application software 3 (TWAIN compliant) Scanner
53 !! Task - Assignment - Exercise!! 105 Make Make a scan scan at at the the highest highest possible resolution 1) 1) in in black black and and white, white, 2) 2) in in gray gray levels, levels, of of a document that that shows shows text text as as well well as as a photograph. Save Save the the data data to to disk. disk. Prepare a sheet sheet of of paper paper with with A) A) the the chosen chosen file file format, format, B) B) the the resulting size size of of the the files, files, C) C) print-outs 2 times times larger larger than than the the original original size. size. For For instance, scan scan the the page page of of your your passport that that shows shows your your portrait portrait or or your your identity identity card card or or your your student student card card **-- How to buy/choose/evaluate/select a scanner? 106 See for instance:»http://buy.com/!»http://computers.cnet.com/»http://computershopper.com/ For reviews/evaluations/opinions on all kinds of products:»http://www.epinions.com/
54 107 Computer technology Multifunctional devices Multifunctional devices: what? 108 Hybrid machines that offer in a single unit a combination of»printing,»scanning,»copying,»and often faxing Colour or black and white Inkjet- or laser-based models
55 Multifunctional devices: pros + and cons Using a multifunctional device allows you to save space, as it is smaller than separate units. + One multifunctional device is less expensive than separate units. - If the unit breaks down, you lose several functions. - The sum is often not as good as a combination of separate individual parts. 110 Computer technology Digital cameras
56 Digital cameras: definition 111 A camera that stores images digitally, instead of recording them on film. A stored image can be dowloaded to a computer, manipulated with a graphics program and printed. **-- Digital cameras: history s-1950 s: evolution of TV 1951: electric impulses are recorded onto magnetic tapes 1960 s: NASA»images processed through a computer and turned into a digital signal»cold war accelerates development of digital imaging 1990 s: first digital cameras for consumers
57 Digital cameras: important components (1) 113 Physical dimensions of the camera Sensor: number of pixels in the picture? Lens: plastic or aspherical glass? Image resolution = resolving power; determined by combination of lens, sensor and internal processing software Focusing: fixed focus or autofocus and/or manual focus? Digital cameras: important components (2) 114 Zoom capabilities: optical zoom (+ digital zoom) Optical viewfinder: separate from lens or reflex or view of the sensor LCD-display: preview and review of images? Size of the display Flash: built-in? power of the flash? external flash possible?
58 Digital cameras: important components (3) 115 Exposure:»only fully automatic or also preset aperture-shutter combinations?»white balance: only automatic or also manually? Storage: internal memory / removable storage cards / floppy disks / CD-R? File formats used: JPEG / GIF / TIFF / RAW Compression settings of files Digital cameras: important components (4) 116 Connectivity to computer: USB 1 or 2? Wireless? Connectivity to a TV: TV-video-out? Batteries: How long do they last? Rechargeable? Audio recording: interesting for identification and notes Video recording: resolution? number of frames per second?
59 Digital cameras: How do they work? Shutter release button halfway down (preparing): autofocus applied, CCD charges up, flash prepares to be used. 2. Shutter button fully depressed: shutter opens, light strikes CCD, light is measured electronically and is sent to internal memory (buffer). 3. Information reaches buffer and is compressed. 4. The completed image is transferred to the storage device. Digital cameras: advantages No film purchase and development cost. + Immediate results. + It is easy to improve images. + Duplication of photo files is easy and cheap. + It is easy and cheap to make a back-up of a collection. + Organising and storing photos requires less time and space.
60 Digital cameras: disadvantages Hardware costs more than a classical film camera. - The quality of prints depends not only on quality of camera, but also on quality of printer. - The size of photos is limited by: - maximum resolution - technology of the digital camera - printer and paper quality Information about digital cameras, that is available through the WWW 120 Many information sources about digital cameras are available through the WWW. The following sites give many details and are therefore recommended:»http://www.acme.com/digicams/»http://www.dpreview.com/»http://www.imaging-resource.com/»http://www.megapixel.net/»http://www.steves-digicams.com/
61 Information about digital cameras, that is available through the WWW 121 A database with secondary information about digital cameras provides links to primary information sources:»http://www.acme.com/digicams/ ** Computer technology Computer-peripheral interfaces
62 **-- Computer-peripheral interfaces: general 123 Terminology: interface / bus / host adapter Standards to control the flow of data (Input / Output) between the computer s processor and its peripheral devices such as printers, scanners, disks, CD-ROMs, file servers (and networks in general) Consist of hardware + software Many types and sub-types Evolution goes on; no stability **--?? Question?? 124 Which types of of computer --peripheral interfaces do do you know?
63 **-- Computer-peripheral interfaces: internal I/O buses 125 ISA = Industry Standard Adapter MCA = Micro Channel Adapter (IBM only) EISA VESA = VL = VESA Local Bus PCI = Peripheral Component Interconnect; is overtaking ISA, EISA, VESA PC Card (was named PCMCIA earlier); Cardbus in recent, fast versions **-- Computer-peripheral interfaces: external I/O buses 126 Parallel = Centronics Serial IDE = Integrated Drive Electronics; IDE ATAPI EIDE = Enhanced IDE SCSI = Small Computer Systems Interface USB = Universal Serial Bus (since 1996) Firewire proprietary interfaces
64 **-- Computer-peripheral interfaces: parallel 127 Mainly used to connect a printer. Enhanced version allows higher transfer speed. Also to connect other peripherals, including SCSI devices, by using a shuttle, but performance is poor. **-- Computer-peripheral interfaces: IDE and EIDE 128 Proposed in For hard disk drives only. Available at low cost (in comparison with PC-cards and SCSI). EIDE = Enhanced IDE, proposed in 1993, supports faster data transfer rates and larger hard disk drives. ATAPI = Attachment Packet Interface, finalised in 1994, supports devices other than hard disk drives, for instance CD-ROM drives.
65 **-- Computer-peripheral interfaces: SCSI 129 Supports 7 (or even more) peripherals in a daisy chain arrangement from a single host interface. Defines a set of software commands which allows to mix peripheral types. Is more expensive than EIDE. **-- Computer-peripheral interfaces: USB Supports peripherals in a daisy chain arrangement from a single host interface. + Defines a set of software commands which allows to mix peripheral types. + Is less expensive than SCSI. + Maximum data transfer rate is higher than with parallel or serial interface.
66 131 Computer technology Computer ergonomics Computer ergonomics: factors determined by the system 132 Radiation emitted by the display (frequency spectrum and level) Display quality (number of colours, resolution, size, refresh rate,...) Keyboard quality (size, tactile feedback, audible click or not, repeat rate,...) Mouse quality (grip, buttons,...) Audio output (volume level, usefulness,...)
67 Computer ergonomics: factors determined by the user 133 Lightning»level and direction»avoid reflections Position of components relative to each other»desk, chair, computer, display, mouse, light sources... In particular, use of the mouse on the desk! **** 134 You are free to copy, distribute, display this work under the following conditions:»attribution: You must mention the author.»noncommercial: You may not use this work for commercial purposes.»no Derivative Works: You may not change, modify, alter, transform, or build upon this work. For any reuse or distribution, you must make clear to others the license terms of this work.