The UNIX*operating system was designed to let a number of programmers access the computer at the same time and share its resources.
The operating system coordinates the use of the computer's resources, allowing one person, for example, to run a spell check program while another creates a document, lets another edit a document while another creates graphics, and lets another user format a document -- all at the same time, with each user oblivious to the activities of the others.
The operating system controls all of the commands from all of the keyboards and all of the data being generated, and permits each user to believe he or she is the only person working on the computer.
This real-time sharing of resources make UNIX one of the most powerful operating systems ever.
Although UNIX was developed by programmers for programmers, it provides an environment so powerful and flexible that it is found in businesses, sciences, academia, and industry. Many telecommunications switches and transmission systems also are controlled by administration and maintenance systems based on UNIX.
While initially designed for medium-sized minicomputers, the operating system was soon moved to larger, more powerful mainframe computers. As personal computers grew in popularity, versions of UNIX found their way into these boxes, and a number of companies produce UNIX-based machines for the scientific and programming communities.
The uniqueness of UNIX
The features that made UNIX a hit from the start are:
- Multitasking capability
- Multiuser capability
- Portability
- UNIX programs
- Library of application software
Multitasking
Many computers do just one thing at a time, as anyone who uses a PC or laptop can attest. Try logging onto your company's network while opening your browser while opening a word processing program. Chances are the processor will freeze for a few seconds while it sorts out the multiple instructions.
UNIX, on the other hand, lets a computer do several things at once, such as printing out one file while the user edits another file. This is a major feature for users, since users don't have to wait for one application to end before starting another one.
Multiusers
The same design that permits multitasking permits multiple users to use the computer. The computer can take the commands of a number of users -- determined by the design of the computer -- to run programs, access files, and print documents at the same time.
The computer can't tell the printer to print all the requests at once, but it does prioritize the requests to keep everything orderly. It also lets several users access the same document by compartmentalizing the document so that the changes of one user don't override the changes of another user.
System portability
A major contribution of the UNIX system was its portability, permitting it to move from one brand of computer to another with a minimum of code changes. At a time when different computer lines of the same vendor didn't talk to each other -- yet alone machines of multiple vendors -- that meant a great savings in both hardware and software upgrades.
It also meant that the operating system could be upgraded without having all the customer's data inputted again. And new versions of UNIX were backward compatible with older versions, making it easier for companies to upgrade in an orderly manner.
UNIX tools
UNIX comes with hundreds of programs that can divided into two classes:
- Integral utilities that are absolutely necessary for the operation of the computer, such as the command interpreter, and
- Tools that aren't necessary for the operation of UNIX but provide the user with additional capabilities, such as typesetting capabilities and e-mail.
