Transcript Free Software

5 V ٥
9
8
7
6
5
4
3
2
1
0
10
new position
?
0
1
2
3
4
5
:
8
9
10
11
:
99
100
101
102
:
10^1
10^2
10^3
0
1
10
11
100
101
:
1000
1001
1010
1011
:
1100011
1100100
1100101
1100111
:
2^1
2^2
2^3
2^4
:
2^7
bit
...1011001011001001000100011111100000101110001...
byte
1 byte = 8 bits = 2^8 = 256
(from 0 to 255)
1 Kilobyte = 1024 bytes
1 Megabyte = 1024 Kilobytes
1 Gigabyte = 1024 Megabytes
1 Terabyte = 1024 Gigabytes
1,048,576 bytes
decimal
1
64
127
128
255
decimal
hexadecimal
binary
0
0
0000
1
1
0001
2
2
0010
3
3
0011
4
4
0100
5
5
0101
6
6
0110
7
binary
8
0111
7
hexadecimal
8
1000
9
1001
9
00000001
A
1001
1140
127F
01000000
B
01111111
C
1011
1380
14FF
10000000
D
11111111
E
1101
15
F
1010
1100
1110
1111
•
# bytes
name
range
1
BYTE
0 to 255
(short unsigned)
•
1
SHORT SIGNED
-128 to +127
(short integer)
•
1
LOGICAL
True or False (1 or 0)
(boolean)
•
2
INTEGER
-32,768 to +32,767
(integer x 2, integer signed)
•
2
INTEGER UNSIGNED
0 to 65,535
•
4
LONG INTEGER
-2,147,483,648 to +2,147,483,647
(integer x 4)
•
4
REAL
-1 x 1038 to +1 x 1038 (7 decimals)
(real x 4, single precision)
•
8
REAL x 2
16 decimals
(real x 8, double precision)
•
any
STRING
(character)
any combination of characters
ASCII table (top)
Non-Printable
Characters
Printable Characters
Decimal:
0
16
32
48
64
80
96
112
Hex:
00
10
20
30
40
50
60
70
Character:
NUL
DLE
SP
0
@
P
\
p
Decimal:
1
17
33
49
65
81
97
113
Hex:
01
11
21
31
41
51
61
71
Character:
SOH
DC1
!
1
A
Q
a
q
Decimal:
2
18
34
50
66
82
98
114
Hex:
02
12
22
32
42
52
62
72
Character:
STX
DC2
"
2
B
R
b
r
Decimal:
3
19
35
51
67
83
99
115
Hex:
03
13
23
33
43
53
63
73
ETX
DC3
#
3
C
S
c
s
Character:
:
:
ASCII vs. binary
01101100011101010110001101100001
real
2.62242E+20
long integer
1,819,632,481
integer
27,765
25,441
byte
?
?
?
string
?
?
The operating system
personal
1979
DOS (to 6.22)
1985
Win 1.0
1992
Win 3.1
1993
workstation
server
NT 3.1
Win 95
1995
ws
NT 3.51
server
1996
NT 4.0
server
pro
2000
server
pro
XP
server
1998
Win 98
ws
2000
Win ME
2001
home
2007
Vista
2009
Win 7
2012
Win 8
The operating system
Free Software
Linus Torvalds
Richard Stallman
Free Software
• The Free Software Foundation
– Four fredooms
• 0: freedom to run the program, for any purpose
• 1: freedom to study how the program works, and change it so it
does your computing as you wish
• 2: freedom to redistribute copies so you can help your neighbor
• 3: freedom to distribute copies of your modified versions to others;
by doing this you can give the whole community a chance to
benefit from your changes
– Access to the source code is a precondition for #1 and #3
Free Software
• The GNU Project was launched
in 1984 to develop the GNU
system. The name “GNU” is a
recursive acronym for “GNU's Not
Unix!”
• A Unix-like operating system is
– a software collection of applications,
libraries, and developer tools,
– plus a program to allocate resources
and talk to the hardware, known as a
kernel
• GNU is typically used today with
a kernel called Linux. This
combination is the GNU/Linux
operating system
Free Software
Free Software
• The GNU General Public License (GNU GPL or GPL)
is the most widely used free software license, which
guarantees end users (individuals, organizations,
companies) the freedoms to use, study, share (copy),
and modify the software
• The GPL is a copyleft license, which means that derived
works can only be distributed under the same license
terms
• In 2001, Microsoft CEO Steve Ballmer referred to GPL
as "a cancer that attaches itself in an intellectual property
sense to everything it touches“
• The term “Open source” was introduced at the end of
90s to avoid the idea of something that is not suitable for
corporate use, due to its being available at no monetary
cost
Free Software
• http://www.netmarketshare.com/?source=NASite
• There are not only laptops and mobiles around the world...
Web servers market share (active sites) – september 2015
Free Software
Free Software
Example of business models
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dual-licensing
selling of support, training, consulting and other services
selling software as a service
partnership with funding organizations
voluntary donations
bounties
pre-order/crowdfunding model
advertising-supported software
selling of optional proprietary extensions
selling of required proprietary parts of a software product
re-licensing under a proprietary license
obfuscation of source code
delayed open-sourcing
etc.
Free Software
Where we find it
• the Internet backbone: routing, DNS, web
servers, mail servers, firewalls
• operating systems: Linux (and Android)
• office suites: OpenOffice, LibreOffice
• web clients: Firefox and Thunderbird
• graphics: Gimp
• databases e.g. MySQL, PostgreSQL
• geomatics, e.g. QGIS, Grass, gvSIG,
Mapserver, GDAL etc.
• have a look to http://www.osgeo.org/