08-21-2001
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Unix is arguably the most important operating system today, and one which we shall frequently refer to below. It comes in many forms, developed by different manufacturers. Originally designed at AT&T, UNIX split into two camps early on: BSD (Berkeley software distribution) and system 5 (AT&T license). The BSD version was developed as a research project at the university of Berkeley, California. Many of the networking and user-friendly features originate from these modifications. With time these two versions have been merged back together and most systems are now a mixture of both worlds. Historically BSD Unix has been most prevalent in universities, while system 5 has been dominant in business environments. The trend during the last three years by Sun Microsystems and Hewlett-Packard amongst others has been to move towards system 5, keeping only the most important features of the BSD system. A standardization committee for Unix called POSIX, formed by the major vendors, attempts to bring compatibility to the Unix world. Here are some common versions of UNIX.
Unix Manufacturer Mainly BSD / Sys 5
BSD Berkeley BSD
SunOS (solaris 1) Sun Microsystems BSD/sys 5
Solaris 2 Sun Microsystems Sys 5
Ultrix DEC/Compaq BSD
OSF 1/Digital Unix DEC/Compaq BSD/sys 5
HPUX Hewlett-Packard Sys 5
AIX IBM Sys 5 / BSD
IRIX Silicon Graphics Sys 5
GNU/Linux Public Domain Posix (Sys V/BSD)
SCO unix Novell Sys 5
Note that the original BSD source code is now in the public domain. Unix is generally regarded as the most portable and powerful operating system available today by impartial judges, but NT is improving quickly. Unix runs on everything from laptop computers to CRAY mainframes. It is particularly good at managing large database applications and can run on systems with hundreds of processors. Most Unix types support symmetric multithreaded processing and all support simultaneous logins by multiple users.
NT is a `new' operating system from Microsoft based on the old VAX/VMS kernel from the Digital Equipment Corporation (VMS's inventor moved to Microsoft) and the Windows32 API. Initially it reinvented many existing systems, but it is gradually being forced to adopt many open standards from the Unix world. It is fully multitasking, and can support multiple users (but only one at a time-- multiple logins by different users is not possible). It has virtual memory and multithreaded support for several processors. NT has a built in object model and security framework which is amongst the most modern in use.
The Be operating system, originally developed for a new multimedia computer called the BeBox, is also new and is a fully multitasking OS. It is optimized for multimedia and is now saleable software developed by Be.Com after the new computer concept failed due to lack of financial backing. BeOS has proper memory protection but allows direct access to video memory (required for fast video games). It also has virtual memory, is pre-emptive multitasking and is based on a microkernel design. Is shares little with Unix except for a Bash shell, a POSIX programming interface and about 150 Unix commands (including Perl).
hope it helps u :-)