1. Introduction to computers and programming

2. Content Hardware Information storage Display File system/type Network
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 Octal Hexadecimal Decimal 0 or 1 0-7 0-9+A-F
How to count =
181 (decimal)
265 (octal)
B5 (hexadecimal)
Signed vs unsigned
0 to 255
-127 to +127

8. Operations on bits Booleans: Operators: Example tables 0 = false = no
1 = true = yes
Operators:
AND OR
XOR
NOT
Example tables
AND 1 OR 1
XOR 1

9. RAM/ROM Size reminder: Kilobyte Kb 210 ~103 Megabyte Mb 220 ~106
Memory mapping
Address Values
0000
0001
0002 ..
FFFF
Size reminder:
Kilobyte Kb 210 ~103
Megabyte Mb 220 ~106
Gigabyte Gb 230 ~109
Terabyte Tb 240 ~1012
Petabyte Pb 250 ~1015 …

10. HD/DVD
track
sector
head

11. Display Fonts Bitmap Vectors TrueType, OpenType, PostScript
Screen 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 of keys) of the keyboard sends a code to the computer.
The code is interpreted and converted to the corresponding ASCII or Unicode number.
The mouse movements
1 to 4 bytes (vertical & horizontal)
Buttons
Clicked, pressed, rolled
buttons

13. ASCII & Unicode ASCII 7/8 bits Unicode od -c od -h UTF-8/16/32 bits
ISO-8859 (Latin)
od -c od -h

14. Word, scripts, mail, web browser…
Software layers
Files
Data (.doc, .mp3)
Software
Word, scripts, mail, web browser…
User Interface
Quartz
CLI, X-Windows
Windows
Operating System
MacOSX
Linux
Windows
ROM
Firmware
BIOS
Hardware
CPU, 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 organisation
Disk 1
Disk 2
Disk 2 C: D: /
DOCS
PROGS
CONFIG
DATA
Directories
/usr
/home
Disk 1
WORD
EXCEL
Subdirectories
EXPT1
EXPT2
local
phil
john
bin
lib
emacs
X11
Windows
Unix

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.txt
suffix
filename
path

18. File types Executable Data Special cases in Unix .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
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 Wired Wireless USB 11Mb-480Mb Ethernet 10Mb-1Gb
Modem 56Kb
ADSL 600Kb-8Mb
LAN 10Mb-10Gb
Wireless
Bluetooth 1Mb-20Mb
WIFI (AirPort) 11Mb-54Mb

21. Network (ethernet or wireless)
Computer talk to each other via network protocols
ip, tcp, http, ftp, …
TCP/IP
transmission control protocol/internet protocol
Handshaking
Transmission
Ackowledgement
DNS
Domain Name Server
URL
Universal Resource Locator
IP addess

22. DNS reminder Primary DNS Root DNS Local DNS Client query Target server1 2 3 4 5 6
*.org
dns.anywhere.net
client.anywhere.net ??

23. Packets
The data travels within units called packets

24. Packet breakout
Usual 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 Data structures Statement, blocks Affectation
Operators
Loops
Tests
Subroutines
Comments
Data structures
Variable
List
Array
Hash
Pointers
Objects

33. Source code (2) Statement, blocks Affectation Operator Variable
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 Tests Subroutines Comments Pointers Objects
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… Do you see any problem?? Try with this:
c=26
d=35
f=23
g=32
h=44
i=90
j=1
k=5
l=33
m=17
n=91
o=104
p=15
q=1
r=43
s=59
t=77
u=52
v=4
w=31
x=2
y=13
z=2
Do 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, $filename) || die "Cannot open file ‘$filename’\n\n";
@text = <FILE>; # add each line of the file to an array
close FILE;
foreach $line { # 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 { # 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 Tuesday Wednesday Thursday Friday
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 presentation…
Vassilios alias
UnixMan!!!