Computer technology. Paul . Nieuwenhuysen @vub.ac.be Vrije Universiteit Brussel Informatie- en Bibliotheekwetenschap, Universitaire Instelling Antwerpen België For UNESCO-ODINAFRICA-MIM June 2001. ****. Computer technology: overview. Automation Computers hardware Character encoding
Computer technology Paul.Nieuwenhuysen@vub.ac.be • Vrije Universiteit Brussel • Informatie- en Bibliotheekwetenschap, Universitaire Instelling Antwerpen België For UNESCO-ODINAFRICA-MIM June 2001
**** Computer technology: overview • Automation • Computers hardware • Character encoding • Output in general;Output to a printer • Scanners • Computer-peripheral interfaces • Computer ergonomics
**-- Computer technology Automation
**-- 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 http://www.britannica.com/
**-- Computer technology:product segments • Large-scale systems • Midrange systems • Workstations • Personal computers • Peripherals • Software • Services • Maintenance • Data communications
Planning / aims / purpose / goals Software Hardware Hardware Planning / aims / purpose / goals Software **-- Computer technology: phases of automation
**-- 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
**-- Components and costs of automation:recurring costs • Continuous training of personnel concerning automation • Support and services • Maintenance of hardware • Software updates • Insurance • ...
**-- 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 e-mail; (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 • Journals (on microcomputers) • PC Magazine (USA, ...) • PC World (USA, UK, ...) • Usenet newsgroups • comp.* • World-Wide Web, for instance with dictionaries: http://dir.yahoo.com/Computers_and_Internet/Information_and_Documentation/Computing_Dictionaries/ http://www.foldoc.org/ • ...
***- Computer technology Microcomputers
***- Hardware components:the computer • Main computer system: CPU, power supply, ports, ... • Video/graphics card/board • Additional RAM • Disk drives and controllers • Video display monitor • ...
***- Hardware components:peripherals • Local area network hardware • Printer • Modem • Power supply in the computer room + backup • Floppy disks • Cables • Mouse • Suitable furniture • ...
***- The microcomputer market shares
**-- Intel microprocessors:evolution • 8088 8086 • 80286 • 80386DX 80386SX 80386SL • 80486DX 80486SX 80486SL • Pentium; Pentium + MMX • Pentium II = PII • Pentium III = PIII; Celeron • Pentium 4 • ...
**--Example Intel microprocessors: growing number of transistors 80286 80386 80486 Pentium
**--Example Intel microprocessors: increasing power (in MIPS) 80286 80386 80486 Pentium
**-- 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
**-- 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) • ...
**-- !? Question !? Task !? Problem !? List and discuss criteria for the evaluation of a microcomputer.
**-- How to buy/choose/evaluate/select a computer? • See for instance: • http://buy.com/ • http://cmp.shop.goto.com/ • http://computers.cnet.com/ • http://www.zdnet.com/computershopper/ • For reviews/evaluations/opinions on all kinds of products: • http://www.epinions.com/
**-- !? 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.
***- Computer technology Character encoding schemes
***- Character encoding schemes: some important standards • EBCDIC ( 8-bit) • ASCII 7-bit 2**7 = 128 • ISO 646 8-bit 2**8 = 2**7 * 2 = 256 • Unicode 16-bit 2**16 = 256*256 = 65 536 01ð?
***- 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.
**-- Character encoding schemes: Unicode • 16 bits per character. • Provides room for 2**16 = 65 536 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)
**-- Computer technology Output
**-- Computer graphics boards and displays: scheme Program Program for Windows Windows Driver software Driver for Windows Computer graphics board Computer display
**-- !? Question !? Task !? Problem !? Which types of computer display do you know?
**-- Computer displays: various types • CRT = Cathode Ray TubeTraditional displays based on the same principle as television and video monitors • Gas-Plasma displayThin 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
**-- !? Question !? Task !? Problem !? Which evaluation criteria do you know for displays?
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 **-- Computer displays: some desirable properties
**-- Computer displays: comparison of various types More than 1 resolution setting yes no Display type CRT LCD Response time + from - to + Heat generation High Low
**-- Computer displays: ergonomics
**-- 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
**-- 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
**-- 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 • ...
**--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 IBM IBM IBM IBM IBM IBM AT&T consortium IBM IBM ... Year 1981 1987 1987 1987 1991 ...
**-- Computer graphics boards and displays: evolution • Many variations ð Lconfusing subject L compatibility problems • Fast evolution to higher quality
**-- How to buy/choose/evaluate/select a computer display? • See for instance: • http://buy.com/ • http://cmp.shop.goto.com/ • http://computers.cnet.com/ • http://www.zdnet.com/computershopper/ • For reviews/evaluations/opinions on all kinds of products: • http://www.epinions.com/
**-- 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 ...
**-- Dot matrix printers • Produce characters by striking pins against an ink ribbon to print closely spaced dots. • Disadvantages: • noise • no high quality output
**-- 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.
**-- !? Question !? Task !? Problem !? Which advantages offer page description languages (such as PostScript)?
**-- 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
**-- 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.
**-- !? Question !? Task !? Problem !? Compare the spatial resolution of common displays and printers (for black characters only).
**-- 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
**-- 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
***- Computer technology Output of characters