2nd Lecture

Data in the computer

• bit
• byte (= 8 bits)
  • one character = one byte
• kilobyte, Kb = 1024 bytes
• megabyte, Mb = 1024 Kb
• gigabyte, Gb = 1024 Mb
  • diskette (floppy disk) = 1.44 Mb
  • harddisk = 400 Mb - 20 Gb
  • RAM = 8 - 64 Mb
  • Cd-Rom = 700 Mb

Storage devices

• temporary: RAM (computer does it for you)
• for a longer time: disk
  • harddisk
    • C: (inside the microcomputer)
    • R: (in the network)
  • CD-ROM
  • floppy disk, A:

File

• most important for the user
• file can be in RAM or on a disk (remember to save!)
• e.g. a text made in WordPerfect has to be saved as a file

Naming Files

• each file must have a unique name
• in DOS (also Windows), the filename has two parts
  • base part is 1 to 8 characters
  • extension is 0 to 3 characters
  • separated by a period
  • MYFILE.TXT
• some extensions
  • .TXT textfile
  • .EXE .COM .BAT programfiles (WPWIN.EXE)
• some programs use their "own" file extensions when saving files
  • .WPD file made in WordPerfect for Windows

some rules in DOS

• each file has a unique name
  • i.e. the path has to be different --> there cannot be two files with the same name in the same directory
• characters that can be used
  • a b c d e ..... z
  • 0 1 2 3 .... 9
  • _ ^ $ ~ ! # % & - { } @ ( )
• characters that cannot be used
  • space , \ . /
  • å ä ö Å Ä Ö = scandinavian characters

Programs = software

It is impossible to use computers without any programs. One should have at least an operating system installed, before one can do anything.

There are basicly two types of software:

1. Operating systems
   • For example DOS, Windows NT, Unix, Apple MacIntosh
   • No computer starts without an operating system: the first program to start as the computer is started is the operating system
   • Operating system controls the Central Prosessing unit and takes care of the resource allocation.
   • In the Helsinki University at the moment there is wide variety of different operating systems: at this course we get used to DOS and take a little peak on Windows NT.
2. Application software
   • e.g. Word Perfect
   • Designed for specific tasks e.g. word processing, browsing the Web, and many others

About Windows 3.11.

• graphical
• is not an operating system
  • needs DOS
• programs
  • are presented as icons...
  • ... which are grouped into program groups
• when a program is running it is in a window
• commands are chosen from menus (no written commands)

• keyboard and mouse
  • move, pointer
  • click and double-click
  • select and drag

• several programs can be open at the same time
  • one of them is active, rest are passive
• program-windows can be arranged, resized, etc.
• programs all look alike
• Windows Tutorial

Windows-programs (general)

• Program Manager, controls Windows
• File Manager
• text editors: Write and Notepad
• MS-DOS Prompt
• a simple drawing program: Paintbrush

Windows-programs (in University's Novell-network)

• Netscape Navigator Browser, Messenger (e-mail), Composer (creating WWW-pages)
• WordPerfect, Ms Word (Word Processors)
• Excel, QuattroPro (Spreadsheets)
• SPSS, SAS (Statistical)
• Corel Draw, Photoshop (Graphics)
• and more and more...

What is a network?

• lots of machines ... connected with wires
• hierarchical
• microcomputer network (local area network) server (all the users files and all the programs)
• Internet
  • international
  • divided into countries and further into areas
  • standard for addresses
  • different ways to "be on the Internet" (gopher, WWW, e-mail, FTP...)

Information system used on the course: World Wide Web

• just another way to show the information on the Internet
• text and graphics (even sound and animation)
• text (and pictures) is hyperlinked
• hard to find information without "Internet search"
• Netscape Navigator is a program for browsing the WWW

Netscape Navigator

• Program group Internet
• Links are highlighted words or icons (click)
• Toolbar

Searching for information from the www

Subject Guides

Categorised lists of links.

Search Engines (using keywords)

When you can't find what you're looking for from a subject guide, its probably a good idea to try a keyword search on a search engine, e. g. Altavista.

A quick guide in Altavista queries

Altavista main search help

Altavista advanced search help

Further reading: Sink or Swim: Internet Search Tools & Techniques

Ordering IMAP (Mappi) mailbox

The IT Department offers IMAP email service through "Mappi". New users get the Mappi mailbox automatically, others can order it via https://www-db.helsinki.fi/perl-bin/mappi_tilaus. The mailbox will be available on the next week day (that is why it has to be ordered at least a day before one is going to use it). Ask the practice teacher for further instructions!

Last updated 25.11. 1999