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introduction for computers

Jul 07, 2015



want to know about computers this ppt will help you

  • 1. Introduction to computers and programing

2. Content Hardware Information storage RAM, ROM HD, DVD Display Images Characters (fonts) File system/type Encryption Compression Network Protocols Packets Programming Algorithm Pseudocode Flowchart Languages Source code Example 3. The computer 4. Internally 5. The connections 6. Information storage 1 bit 8 bits 16 bits 32 bits 64 bits bit (1 or 0) byte (octet) (28) word (216) double (232) long double (264)Encoding information on a fixed element of length n with a base b gives bn non-redundant possibilities 7. Information coding Binary 0 or 1 Octal 0-7 Hexadecimal 0-9+A-F Decimal 0-9 How to count 128 64 32 16 8 10110421101 128+32+16+4+1= 181 (decimal) 265 (octal) B5 (hexadecimal) Signed vs unsigned 0 to 255 -127 to +127 8. Operations on bits Booleans: 0 = false = no 1 = true = yes Operators: AND OR XOR NOT Example tables AN D01000101OR01001111XO R01001110 9. RAM/ROM Memory mapping Address Values 1 0 1 1 1 0 0 1 0000 0 0 0 0 1 1 1 1 0001 1 1 1 0 0 0 1 1 0002 .. .. .... FFFF0 0 1 0 0 1 0 0 Size reminder: Kilobyte Megabyte Gigabyte Terabyte Petabyte Kb Mb Gb Tb Pb210 ~103 220 ~106 230 ~109 240 ~1012 250 ~1015 10. HD/DVD track sector head 11. QuickTime et un dcompress eur TIFF (non compress) sont requis pour visionner cette image. DisplayScreen pixel or dots Color coding: 32 bits 1 pixel = 3 bytes of color (RGB)+1 byte alpha channel (transparency) 1600x1200x4bytes=7,5 Mb! Fonts Bitmap Vectors TrueType, OpenType, PostScript 12. Keyboard/Mouse Each key (or combination The mouse movements 1 to 4 bytes (vertical & of keys) of the keyboard horizontal) sends a code to the Buttons computer. Clicked, pressed, rolled The code is interpreted and converted to the buttons corresponding ASCII or Unicode number. 13. ASCII & Unicode ASCII 7/8 bits Unicode UTF-8/16/32 bits ISO-8859 (Latin) od -c od -h 14. Software layers FilesData (.doc, .mp3)SoftwareWord, scripts, mail, web browserUser InterfaceQuartzCLI, X-WindowsOperating SystemMacOSXROMFirmwareHardwareWindows WindowsLinuxBIOSCPU, RAM, HD, DVD 15. File systems Method the OS uses to store information Storage unit, directories, subdirectories (Windows, VMS) Single arborescence (Linux, MacOSX, all Unix) What exactly is a file? a piece of information (text, graphic, data, music program, script) it is identified by a name and an logical address (or path) other informations: date, size, type, creator, ownership, physical address 16. File system organisationDisk 1Disk 2C: DOCSDisk 2D: PROGSWORDEXCELCONFIG/DirectoriesDATAEXPT1EXPT2/usrDisk 1Subdirectories binlocalphil libemacsWindows/homeUnixX11john 17. Path The path is the logical address used by the system or the user to locate a file. Example: /bd_du_Palais/35/etage/4/appart/12/Dupont_ Jean.txtpathfilenamesuffix 18. File types Executable .exe .app Unix requires x Data Text (.txt) Music (.mp3) Image (.jpg, .gif) Movie (.mpg, .mov) Binary (.bin) Special cases in Unix STDIN STDOUT STDERR 19. Encryption / compression Compression Reducing the size of files E.g., .mp3, .gz, .jpg, .zip Encryption Protecting your privacy E.g., .pgp Packing Grouping the files E.g., .tar 20. Networks Direct USB 11Mb-480Mb Ethernet 10Mb-1GbWired Modem 56Kb ADSL 600Kb-8Mb LAN 10Mb-10GbWireless Bluetooth 1Mb-20Mb WIFI (AirPort) 11Mb-54Mb 21. Network (ethernet or wireless) Computer talk to each other via network protocols ip, tcp, http, ftp, Handshaking Transmission Ackowledgement TCP/IP DNS transmission control protocol/internet protocol Domain Name Server URL Universal Resource Locator IP addess 22. DNS reminder 3Root DNS2*.org45 Local DNSPrimary DNSdns.anywhere.netwww.expasy.org16Client query ??Target server 23. Packets The data travels within units called packets 24. Packet breakoutUsual TCP/IP payload per packet: 512 bytes 25. Introduction to programming 26. What is a program? How to cook? The algorithm Are you a programmer? 27. Pseudocode This is the pseudocode for a game of Monopoly 28. Flowcharts 29. Flowcharts details 30. Languages Low level (processor dependent) Machine code, assembler High level: structured, procedural Fortran, C, Pascal High level: object oriented C++, Java, C#, Perl, Objective-C Virtual machines Java, C# Scripting Perl, Python, JavaScript 31. Source code -> Object code Compiler+linker Fortran, C, Pascal, C++ Interpreter Basic, Perl Intermediate Java Compiler+linker Fast to execute, but slow to debug Interpreter Slow to execute, but fast to debug (no need to recompile) Intermediate Slow 32. Source code Instructions Statement, blocks Affectation Operators Loops Tests Subroutines Comments Data structures Variable List Array Hash Pointers Objects 33. Source code (2) Statement, blocks One or more instructions for the processor Affectation Change to a variable Operator affect one or more variable + * - / AND OR NOT Variable A region in memory that can be modified Exists in different types Scalar, char, numeric, boolean List, array Hash Combination->data structure 34. Source code (3) Loops Allow the computer to repeat blocks Tests Decide what to do Subroutines Programs frequently called (functions) Comments The most important lines of the source code Pointers Reference to region in memory (address) Objects Combination of data and code 35. Example: a text to treat Noon rings out. A wasp, making an ominous sound, a sound akin to a klaxon or a tocsin, flits about. Augustus, who has had a bad night, sits up blinking and purblind. Oh what was that word (is his thought) that ran through my brain all night, that idiotic word that, hard as I'd try to pun it down, was always just an inch or two out of my grasp - fowl or foul or Vow or Voyal? - a word in a quizz which, by association, brought into play an incongruous mass and magma of nouns, idioms, slogans and sayings, a confusing, amorphous outpouring which I sought in vain to control or turn off but which wound around my mind a whirlwind of a cord, a whiplash of a cord, a cord that would split again and again, would knit again and again, of words without communication or any possibility of combination, words without pronunciation, signification or transcription but out of which, notwithstanding, was brought forth a flux, a continuous, compact and lucid flow: an intuition, a vacillating frisson of illumination as if caught in a flash of lightning or in a mist abruptly rising to unshroud an obvious sign - but a sign, alas, that would last an instant only to vanish for good.Gilbert Adair 36. Result a=97 b=15 c=26 d=35 f=23 g=32 h=44 i=90 j=1 k=5 l=33 m=17n=91 o=104 p=15 q=1 r=43 s=59 t=77 u=52 v=4 w=31 x=2 y=13 z=2Do you see any problem?? Try with this: The quick brown fox, jumps over the lazy dog. 37. Flowchart 38. Source code example #!/usr/bin/perl -w# essential line of all perl scripts$filename = "avoid.txt"; # affect avoid.txt to the variable $filename # open the file, or exit open(FILE, $filename) || die "Cannot open file $filenamenn"; @text = ; # add each line of the file to an array close FILE; foreach $line (@text) { # read one line from the array into $line and repeat for each line @table = split(//,$line); # read each character of the line in an array while ($char=pop(@table)) { # read one character of the array 'table' and repeat for all $char =~ s/[^a-z]//; # keep only the alphabetical character a to z if ($char) { # check if the character exists and execute the block $count{$char}++; # if yes, increment by one the hash 'count' } } } # print each character and its number of occurence one per line foreach $c (keys %count) { print "$c=$count{$c}n"; } exit; # quit the program 39. Tips Think about your problem Create a flowchart Create the pseudocode Verify the memory used by your variables Write the code Test the code For all the possible functions or cases (if possible) Give it to users as a beta (if not possibe) Sell it (if you work for Microsoft ;-) Debug 40. Summary of the week Monday Intro computers & programming Intro Unix Tutorial Unix Tuesday Intro Perl Regexp & Perl In-liners Wednesday Object Oriented programming BioPerl EMBOSS Thursday Database indexing BLAST HTML & cgi-bin Friday Finish exercises Users questions 41. Unix Next presentationVassilios alias UnixMan!!!