Operating systems


The operating system, designed by Bell Laboratories in the USA for microcomputers, has been widely adopted by many corporate installations. From the very first, it was designed to be a multitasking system. It is written in C language.

It has become an operating environment for software development, available for any type of machine, from IBM PS/2s to Macs to Cray supercomputers. UNIX is the most commonly used system for advanced CAD programs.



Most of the Mac OS code is in ROM chips. These contain hundreds of routines (sequences of instructions) which perform such tasks as starting up the computer, transferring data from disk to peripherals and controlling the RAM space.

Large parts of the Mac OS are also inside the system file and the finder, kept in the system folder. The content of the system file is loaded automatically at start-up, and contains information which modifies the routines of the OS in the ROM chips. The finder displays the Macintosh's desktop and enables the user to work with disks, programs and files.

Mac OS X provides a luscious, liquid interface, called Aqua, across every application and the utilities you need to control and customize your Mac. Plus, you can easily connect your Mac to any network - whether wired or wireless, Mac-, UNIX- or Windows-based. And it all just works.


OS/2 Warp

This is the world's most technically sophisticated operating system. It provides true multitasking, allowing a program to be divided into "threads", many of which can be run at the same time. Thus, not only can numerous programs run simultaneously, but one program can perform numerous tasks at the same time. The IBM OS/2 Warp includes easy access to networks via modem, support for Java applications and voice recognition technology.



Protected under the GNU general public license, Linux is the open source, cooperatively-developed multitasking operating system. Linux is used as a high value, fully functional UNIX workstation for applications ranging from internet servers to reliable work group computing.



Spreadsheet programs

Spreadsheet programs are another type of applications software. They are similar to word processors - you can even use a spreadsheet program to write texts - but their main purpose is to calculate and present numbers and data in a table format. When you open a spreadsheet program you will notice that the screen is divided into rows and columns. In each of the boxes created by these horizontal and vertical lines you can put in either letters, words, sentences or numbers, even complete mathematical formulas.

Thus the user can tell the program to do all possible mathematical calculations with the numbers, in the boxes above or to the left or anywhere within one or more spreadsheets. For example, you can add up figures, divide them, or work out a certain percentage. You can also transform the numbers into graphs that can be presented to the reader, perhaps to illustrate the development of a company's turnover. As with a word processor, you can format your printout, e.g. by choosing different fonts.


Wordprocessing programs



Programs and applications

  graphics program wordprocessing program spreadsheet program database program electronic mail
add colour to objects          
number chapters automatically          
calculate figures          
change the value of cells          
control all sorts of data          
create rectangles or other shapes          
display information in the form of a table          
draw and manipulate objects          
exchange information with other computer users          
invert a picture          
make an object larger or smaller          
produce pie charts or line graphs          
proofread documents using a spell checker          
rotate an image          
search and replae particular words          
write faxes          



Hacker Vladimir Levin in St. Petersburg, Russia, used his laptop computer to transfer illegally at least $3.7-million from New York's Citibank to accounts around the world


A Boston group of hackers known as L0pht said, they could cut the entire nation off from the Internet in less than 30 minutes.

In 1989, an Indiana hacker altered phone switches so that calls to a Florida county probation department rang instead at a New York phone-sex line answered by "Tina."


Hackers mangled the Central Intelligence Agency site to read "Central Stupidity Agency."

A Web site featuring information about Florida's Supreme Court was hacked and adorned with porno­graphic pictures in late 1996.

In Citrus County, hackers operated a Web site that accused a local teacher of having a homosexual affair.

The airline AirTran whose passenger jet crashed in the Everglades in 1996, had its Web site mangled last year. Hackers inserted an image of a burning plane and the line "Fly us because crashing is fun."


Teenage hackers "Makaveli" in California and "Analyzer" in Israel cracked the Pentagon's computer system and took software used to track military satellites.


Tips against hacking (given by Kevin Mitnick, hacker)


Steps of Programming