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1 For UNESCO-ODINAFRICA-MIM
Computer technology Vrije Universiteit Brussel Informatie- en Bibliotheekwetenschap, Universitaire Instelling Antwerpen België For UNESCO-ODINAFRICA-MIM June 2001

2 Computer technology: overview
**** Computer technology: overview Automation Computers hardware Character encoding Output in general; Output to a printer Scanners Computer-peripheral interfaces Computer ergonomics

3 **-- Computer technology Automation

4 Information processing: an introduction
**-- Information processing: an introduction For an introduction to the broad subject of information processing and computer-supported information processing in particular, see encyclopedia articles like the one on “information processing” in Encyclopedia Britannica, available online and free of charge from

5 Computer technology: product segments
**-- Computer technology: product segments Large-scale systems Midrange systems Workstations Personal computers Peripherals Software Services Maintenance Data communications

6 Computer technology: phases of automation
**-- Computer technology: phases of automation Planning / aims / purpose / goals Software Hardware Hardware Planning / aims / purpose / goals Software

7 Components and costs of automation: initial costs
**-- Components and costs of automation: initial costs System planning and acquisition Personnel + consulting + visits of other users + participation to conferences + ... Personnel costs during initial training + teacher(s) + ... Software Hardware Installation; cables

8 Components and costs of automation: recurring costs
**-- Components and costs of automation: recurring costs Continuous training of personnel concerning automation Support and services Maintenance of hardware Software updates Insurance ...

9 General evaluation criteria for computer products
**-- General evaluation criteria for computer products 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?

10 Computer technology: some information sources
**-- Computer technology: some information sources Journals (on microcomputers) PC Magazine (USA, ...) PC World (USA, UK, ...) Usenet newsgroups comp.* World-Wide Web, for instance with dictionaries: ...

11 ***- Computer technology Microcomputers

12 Hardware components: the computer
***- Hardware components: the computer Main computer system: CPU, power supply, ports, ... Video/graphics card/board Additional RAM Disk drives and controllers Video display monitor ...

13 Hardware components: peripherals
***- Hardware components: peripherals Local area network hardware Printer Modem Power supply in the computer room + backup Floppy disks Cables Mouse Suitable furniture ...

14 The microcomputer market shares
***- The microcomputer market shares

15 Intel microprocessors: evolution
**-- Intel microprocessors: evolution 80286 80386DX SX SL 80486DX SX SL Pentium; Pentium + MMX Pentium II = PII Pentium III = PIII; Celeron Pentium 4 ...

16 Intel microprocessors: growing number of transistors
**--Example Intel microprocessors: growing number of transistors Pentium

17 Intel microprocessors: increasing power (in MIPS)
**--Example Intel microprocessors: increasing power (in MIPS) Pentium

18 Computer memory chips: ROM versus RAM
**-- Computer memory chips: ROM versus RAM Types 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 ROM is slower than RAM

19 Computer memory chips: types of RAM
**-- Computer memory chips: types of RAM 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) ...

20 List and discuss criteria for the evaluation of a microcomputer.
**-- !? Question !? Task !? Problem !? List and discuss criteria for the evaluation of a microcomputer.

21 How to buy/choose/evaluate/select a computer?
**-- How to buy/choose/evaluate/select a computer? See for instance: For reviews/evaluations/opinions on all kinds of products:

22 !? Question !? Task !? Problem !? **--
Read Chapter 1 about “Computer hardware “ in Part one: Fundamental aspects of computing and related technologies, in William Saffady, Introduction to automation for librarians, Chicago : ALA, 1999.

23 Character encoding schemes
***- Computer technology Character encoding schemes

24 Character encoding schemes: some important standards
***- Character encoding schemes: some important standards 01 ð? EBCDIC ( 8-bit) ASCII bit 2**7 = ISO bit 2**8 = 2**7 * 2 = Unicode 16-bit 2**16 = 256*256 =

25 Character encoding schemes: ASCII and extensions
***- Character encoding schemes: ASCII and extensions 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 2*128 = 256 characters. However, there is no standard for the upper 128 codes; the upper 128 characters vary from system to system.

26 Character encoding schemes: Unicode
**-- Character encoding schemes: Unicode 16 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 Unique: with minimal duplication of character codes (important for Chinese characters)

27 **-- Computer technology Output

28 Computer graphics boards and displays: scheme
**-- Computer graphics boards and displays: scheme Program Program for Windows Windows Driver software Driver for Windows Computer graphics board Computer display

29 Which types of computer display do you know?
**-- !? Question !? Task !? Problem !? Which types of computer display do you know?

30 Computer displays: various types
**-- Computer displays: various types 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

31 Which evaluation criteria do you know for displays?
**-- !? Question !? Task !? Problem !? Which evaluation criteria do you know for displays?

32 Computer displays: some desirable properties
**-- Computer displays: some desirable properties J High contrast J High brightness J Sharp display; small dot size J Large size of the display screen J Small physical size J Low heat generation J Low power consumption J Low distortion of images J Lack of “ghosting” in the case of LCD displays J Low emission of radiation that may harm the user J Low price

33 Computer displays: comparison of various types
**-- Computer displays: comparison of various types Display type CRT LCD More than 1 resolution setting yes no Response time + from - to + Heat generation High Low

34 Computer displays: ergonomics
**-- Computer displays: ergonomics

35 Computer graphics boards and displays: resolution
**-- Computer graphics boards and displays: resolution 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

36 Computer graphics boards and displays: desirable properties
**-- Computer graphics boards and displays: desirable properties J High spatial resolution J High number of colours displayable at the same time J High refresh rate = no flicker J High speed of display

37 Computer graphics boards: factors determining their quality
**-- Computer graphics boards: factors determining their quality Amount of video RAM Speed of the video microprocessor Software (“drivers”) for the communication between programs and the display ...

38 Computer graphics boards for microcomputers with Intel processors
**--Example Computer graphics boards for microcomputers with Intel processors 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 AT&T consortium ... Year 1981 1987 1991 ...

39 Computer graphics boards and displays: evolution
**-- Computer graphics boards and displays: evolution Many variations ð L confusing subject L compatibility problems Fast evolution to higher quality

40 How to buy/choose/evaluate/select a computer display?
**-- How to buy/choose/evaluate/select a computer display? See for instance: For reviews/evaluations/opinions on all kinds of products:

41 Printer types **-- Type price noise quality speed
Dot matrix low high Inkjet low low Inkjet (+PostScript) high low Laser / LED high low Laser (+PostScript) highest low Solid ink ...

42 Dot matrix printers **--
Produce characters by striking pins against an ink ribbon to print closely spaced dots. Disadvantages: noise no high quality output

43 Solid ink printers **--
Developed in the beginning of the 1990s by Tektronix. Marketed almost exclusively by Tektronix. They use solid wax ink sticks instead of toner.

44 !? Question !? Task !? Problem !? **--
Which advantages offer page description languages (such as PostScript)?

45 Page description language interpreter in printers: advantages
**-- Page description language interpreter in printers: advantages 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

46 Page description language interpreter in printers: disadvantages
**-- Page description language interpreter in printers: disadvantages 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.

47 !? Question !? Task !? Problem !? **--
Compare the spatial resolution of common displays and printers (for black characters only).

48 **-- Resolution of displays and printers for documents with black characters only 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

49 Colour ranges supported by video displays and printers
**-- Colour ranges supported by video displays and printers Range of colours supported by various processes = “gamut” Visible colour gamut Video display gamut Colour printer gamut

50 ***- Computer technology Output of characters

51 !? Question !? Task !? Problem !? **--
Where in the system that you use are the characters (fonts) stored that will be printed: on the computer or on the printer?

52 Printing characters: overview of various methods (1)
**-- Printing characters: overview of various methods (1) 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

53 Output of characters using bitmap fonts in the printer
**-- Output of characters using bitmap fonts in the printer User Microcomputer Application software Display fonts Display driver Printer driver Fonts / Typefaces Print-out Display

54 Printing characters: overview of various methods (2)
**-- Printing characters: overview of various methods (2) 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

55 Output of characters using bitmap fonts in the computer
**-- Output of characters using bitmap fonts in the computer User Microcomputer Application software Display fonts Printer fonts Display driver Printer driver Display Print-out

56 Printing characters: overview of various methods (3)
**-- Printing characters: overview of various methods (3) 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

57 Output of characters using scaleable fonts in the printer
**-- Output of characters using scaleable fonts in the printer User Microcomputer Application software Display fonts Display driver Printer driver scaleable fonts / typefaces Processing of characters to bitmaps Print-out Display

58 Printing characters: overview of various methods (4)
**-- Printing characters: overview of various methods (4) 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

59 Output of characters using TrueType processed on the computer only
**-- Output of characters using TrueType processed on the computer only User Microcomputer Microsoft Windows application software Microsoft Windows TrueType display and printer fonts Display driver Printer driver Processing of characters to bitmaps Display Print-out

60 Printing characters: overview of various methods (5)
**-- Printing characters: overview of various methods (5) 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

61 Output of characters using TrueType processed on computer + printer
***- Output of characters using TrueType processed on computer + printer User Microcomputer 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 Display

62 List and discuss criteria for the evaluation of a printer.
**-- !? Question !? Task !? Problem !? List and discuss criteria for the evaluation of a printer.

63 How to buy/choose/evaluate/select a printer?
**-- How to buy/choose/evaluate/select a printer? See for instance: For reviews/evaluations/opinions on all kinds of products:

64 Which method do YOU use to print from your computer?
**-- !? Question !? Task !? Problem !? Which method do YOU use to print from your computer?

65 **-- Computer technology Scanners

66 Which applications do you know of scanners?
**-- !? Question !? Task !? Problem !? Which applications do you know of scanners?

67 Scanners: applications
**-- Scanners: applications DTP = desk-top publishing (pictures) OCR = optical character recognition FAX document imaging, for archives and for document transmission using computer networks bar code scanning scanning of signatures for on-line comparison with images stored in the central computer ...

68 Which types of scanners do you know?
**-- !? Question !? Task !? Problem !? Which types of scanners do you know?

69 Scanners: various types
**-- Scanners: various types Flatbed scanners Hand-held scanners Sheet feeding scanners Drum scanners Film scanners Photo CD system Digital cameras Barcode scanners

70 !? Question !? Task !? Problem !? **--
How can a fax system be built from a computer + a scanner + ...? Which hardware and software is required?

71 Scanners: number of bits per pixel
**-- Scanners: number of bits per pixel bits per pixel 1 4 8 24 = 3*8 30 = 3*10 36 = 3*12 ... Result line art = black or white 16 levels of gray 256 levels of gray 256 levels for each of the 3 primary colours 1 024 levels for each of the 3 primary colours 4 096 levels for each of the 3 primary colours ...

72 How can this size be reduced?
**-- !? Question !? Task !? Problem !? When a printed page is scanned at 300 dpi and 256 gray levels, then how large is the resulting file? How can this size be reduced? 21x29 cm = 7x11 inch = 80 square inch 300dpi*300dpi = dots per square inch dus 80* dots = dots 1 dot bits byte conclusie: 700 Kbytes Compression

73 !? Question !? Task !? Problem !? **--
256**3 are many colours in comparison with the limited number of colours available to a painter for instance. Nevertheless, it can be difficult to achieve an acceptable quality by scanning a work of art for instance. Explain this paradox. Painter can mix colours to achieve more than 256**3 possibilities The 256**3 colours from a scanner are in most cases spread over the whole spectrum, whereas in some cases also many subtle variations of one or a few colour must be scanned in the same picture.

74 !? Question !? Task !? Problem !? **--
How much bigger is the resulting file, when the spatial resolution is increased from 150 to 300 dots per inch, without compression? Not 2 but 4

75 !? Question !? Task !? Problem !? **--
If the number of gray levels in scanning is increased from 2 (black or white) to 256, then how much bigger becomes the resulting computer file? Instead of 1 bit 8 bits /pixel; so 8 x bigger

76 Scanners: how to handle gray levels
**-- Scanners: how to handle gray levels 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

77 Scanners: the TWAIN standard
**-- Scanners: the TWAIN standard 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.

78 Scanners: the TWAIN standard scheme
**-- Scanners: the TWAIN standard scheme

79 !? Question !? Task !? Problem !? **--
Make a scan at the highest possible resolution 1) in black and white, 2) in 256 gray levels, of your passport, student card, or another personal document that shows text as well as a photograph. Save the data to disk. Prepare a sheet of paper with A) the chosen file format, B) the resulting size of the files, C) print-outs 2 times larger than the original size.

80 How to buy/choose/evaluate/select a scanner?
**-- How to buy/choose/evaluate/select a scanner? See for instance: For reviews/evaluations/opinions on all kinds of products:

81 Computer-peripheral interfaces
**-- Computer technology Computer-peripheral interfaces

82 Computer-peripheral interfaces: general
**-- Computer-peripheral interfaces: general 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

83 Which types of computer - peripheral interfaces do you know?
**-- !? Question !? Task !? Problem !? Which types of computer - peripheral interfaces do you know?

84 Computer-peripheral interfaces: internal I/O buses
**-- Computer-peripheral interfaces: internal I/O buses 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)

85 Computer-peripheral interfaces: external I/O buses
**-- Computer-peripheral interfaces: external I/O buses Parallel = Centronics Serial IDE = Integrated Drive Electronics; IDE - ATAPI EIDE = Enhanced IDE SCSI = Small Computer Systems Interface USB = Universal Serial Bus (since 1996) proprietary interfaces

86 Computer-peripheral interfaces: parallel
**-- Computer-peripheral interfaces: parallel Mainly used to connect a printer. Also to connect other peripherals, including SCSI devices, by using a “shuttle”, but performance is poor. Enhanced version allows higher transfer speed.

87 Computer-peripheral interfaces: IDE and EIDE
**-- Computer-peripheral interfaces: IDE and EIDE Proposed in 1983. 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.

88 Computer-peripheral interfaces: SCSI
**-- Computer-peripheral interfaces: SCSI Supports up to 7 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.

89 Computer-peripheral interfaces: USB
**-- 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, but is lower than with SCSI.

90 **-- Computer technology Computer ergonomics

91 Computer ergonomics: factors determined by the system
**-- Computer ergonomics: factors determined by the system 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,...)

92 Computer ergonomics: factors determined by the user
**-- Computer ergonomics: factors determined by the user Lightning level and direction avoid reflections Position of components relative to each other desk, chair, computer, display, mouse, light sources,... ...


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