Informatics

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CHAPTER 1
INFORMATION
AND INFORMATICS
contents
Information Management inside a computer
1.4
1.1 INFORMATION
Concept:
Information is new knowledge that is comprehended and is useful to solve a problem
Units of Information: ways of measuring a quantity of information
bit (Binary digit): basic unit, an information with 2 states: 0/1
A device with two stable positions, such as a relay or a transistor, can store one bit of information.
1 Byte = 8 bit
1 KB = 1024 (210) Byte
1 MB = 1024 (210) KB
1 GB = 1024 (210) MB,...
1.2 Informatics
Concept:
Informatics is the science of information, the practice of information processing, and the engineering of information systems
Two main fields of study in Informatics:
Hardware: All electronic and mechanical parts that make up a computer (real entities)
Software: Programs and Data (Information)
1.3 computer
Computer is an electronic device for storing and processing information automatically, by the means of instructions stored in memory.
History of computers:
1642: Mechanical Calculator (Pascal)
1946-1955: 1st generation
1946: ENIAC - John Mauchley and J. Presper Eckert
1955-1965: 2nd generation (with transistors)
1965-1980: 3rd generation (with Integrated Circuit - IC)
1980 up to now: 4th generation ( with Very Large Scale Integration - VLSI)
Types of computers:
Supercomputer, Mainframe: used for Servers
Personal Computer, Microcomputer:
- Desktop computer
- Laptop, Notebook
- Palmtop, Pocket PC
Microcontroller:
- Mobile Phones, RFID chips, some electrical home appliances (washing machines, air conditioners,.)
Computer hardware diagram:





Input devices: for entering data into a computer
Output devices: for retrieving data from a computer

1. SYSTEM UNIT
Chip (CPU – Central Processing Unit)
For data processing and system controlling
Arithmetic-Logic Unit
(ALU)
Control Unit
(CU)
Registers
Internal Memory (RAM & ROM)
· Internal Memory:
- RAM (Random Access Memory):
+ Holds the instructions and data which are currently being processed by CPU.
+ All information stored in RAM will be lost when the power is down (temporary storage)
+ Capacity: MB, GB
- ROM (Read Only Memory):
+ Stores essential instructions/programs (for booting the computer)
+ Information is recorded by ROM manufacturer and can NOT be changed
· External Memory: storage disks
- Floppy disks:
+ Disk drive names: A, B
+ Capacity: 1,44 MB
+ Very slow and unreliable (mostly disappeared from storage devices market)
- Hard disks:
+ Disk drive names: C (D, E, F, ...)
+ Capacity: hundreds of GBs
+ Most important storage devices, very fast and reliable
- Optical disks: CD, DVD (-ROM, -R, -RW, -RAM)
+ Disk drive names: D (E, F, G, ...)
+ Capacity: CD 700 MB, DVD 4.7 GB
+ Durability: 100 years (in theory)
- USB Flash disks:
+ Disk drive names: E (F, G, H, ...)
+ Capacity: hundreds of MB to several GB
+ Most useful storage devices, also the most popular virus transmitter
Power supply
CPU socket
ROM
Expansion Slots
RAM Slots
Connection to Hard disks (IDE cable)
MAIN BOARD: connecting all devices inside system Unit
2. Keyboard.
Bảng phím chữ
3. Monitor
Displaying data in the forms of pictures and text
Specifications:
- Resolution: number of pixels (horizontally and vertically)
- Color depth: number of colors
- Refresh rate: number of frames per second
4. Printer
- Printing data onto paper surface
- Specifications: resolution (dots per inch - DPI)
speed (pages per minute - PPM)
- Types of printers:
Dot-matrix printers
Inkjet printers
Laser printers: 600 DPI, 1200 DPI.
1.4 Information Management inside a computer
1.4.1- File
Concept: A collection of data on a digital recording medium treated as a unit for the purpose of recording, reading, storage, and accessible by computer programs by the use of a filename.
- Filenames: no more than 250 characters, including alpha-numeric characters and other symbols (except: / : ? " < > | )

- Filename extensions: .doc, .xls, .exe, .com
.doc: Documents (Microsoft Word)
.xls: Workbook (Microsoft Excel)
.exe, .com: Executable files (programs)

- Full name: filename.extension
Examples: Report.DOC, Payroll.XLS

1.4.2- Directory, Folder.
For storing files and sub-directories (subfolders)
- Folder names: similar to filenames, but have no extensions
- Structure of Folder system: each folder could have subfolder(s), forming a folder-tree
A typical folder tree
1.4.3- Path
For showing where files and folders are stored inside a folder tree.
Example:
C:Program FilesMicrosoft OfficeOffice 11Winword.exe
1.5 Computer network
1.5.1 Concept
A collection of computers connected to others for data communication and for resources sharing.
A computer network may includes:
Workstations, Clients
Servers: providing services for Clients (Web server, File server, Mail server, ...)
Network devices: connecting computers and other network devices: cable, hub, switch, modem, router, firewall, ...
1.5.2 Computer Network Architecture
Topology: ways to connect computers





Protocol: set of rules and regulation for data communication through network
1.5.3 Computer Networks Classification:
LAN (Local Area Network): inside an office, a building
Intranet: inside an organization
MAN (Metropolitan Area Network): inside a city
WAN (Wide Area Network): inside a region or a country
GAN (Global Area Network): world-wide scope
Internet: a GAN, connecting most of computer networks around the world
1.5.4 Internet:
History: developed from a project of Department of Defense (ARPANET - Advanced Research Projects Agency Network, June 1968).
Starting with 4 computers (placed at Stanford Institute, California University in Los Angeles, California University in Santa Barbara and Uhta University)
Network Architecture:
- Topology: mesh (mixture of different types)
- Protocol: TCP/IP
(Transmission Control Protocol / Internet Protocol)
Internet services distribution diagram

Highest regulating organization: Internet Society (ISOC)
Regional and National regulating organization: NIC (Network Information Center)
- Asia-Pacific region: APNIC
- Vietnam: VNNIC
IAP (Internet Access Provider)
ISP (Internet Service Provider)
Internet connecting media:
- For Internet subscribers:
Based on existing connections: Dial-up, ADSL, WAP, TV- Cable, Power line
Separate connections: ISDN, Leased line (T1 .. T4)

- For IAP`s, ISP`s: Cable-optic, Satellite