Brief of Mac OS

Mac OS is Apple Computer's operating system for Apple Macintosh computers. Mac OS was the first commercially successful operating system which used a graphical user interface. The Macintosh team included Bill Atkinson and Jef Raskin. There are a variety of views on how the Macintosh was developed, and where the underlying ideas originated. While the connection between the Macintosh and the Alto project at Xerox PARC has been established in the historical record, the earlier contributions of Ivan Sutherland's Sketchpad and Doug Engelbart's On-Line System are no less significant. See History of the GUI, and Apple v. Microsoft.

The Mac OS can be divided into two families of operating systems:

An older and now unsupported "classic" Mac OS (the system that shipped with the first Mac in 1984 and its descendants, culminating with Mac OS 9).

The newer Mac OS X (pronunced oh-es-ten). Mac OS X incorporates elements of BSD Unix, OPENSTEP, and Mac OS 9. Its low-level UNIX-based foundation, Darwin, is open source.

Classic Mac OS

The "classic" Mac OS is characterized by its total lack of a command line; it is a 100% graphical operating system. Heralded for its ease of use, it is also criticized for its almost total lack of memory management, cooperative multitasking, and susceptibility to extension conflicts. "Extensions" are program modules that extend the operating system, providing additional functionality (such as a networking) or support for a particular device. Some extensions are prone not to work properly together, or only when loaded in a particular order. Troubleshooting Mac OS extensions can be a time-consuming process. The MacOS also introduced a new type of filesystem, which contained two different "forks" for a file. It was innovative at the time for separating out parameters into the resource fork, and raw data in the "data fork". However, it became quite a challenge to interoperate with other operating systems which did not recognize such a system.

The term "Mac OS" was not officially used until 1996 with the release of Mac OS 7.6 - prior to that the Macintosh operating system software was simply known as "The System", or by its version number, e.g. System 6 or System 7. Another common term was "the Toolbox". Apple deliberately played down the existence of the operating system in the early years of the Mac to help make the machine appear more user-friendly and to distance it from other systems such as MS-DOS, which were portrayed as arcane and technically challenging. With Mac, you turned it on, it just worked.

By the late 1990s, it was clear the useful life of this 1980s-era technology was coming to an end, with other more stable multitasking operating systems being developed.

Mac OS X

Mac OS X remedied this situation, bringing Unix-style memory management and preemptive multitasking. Improved memory management allowed more programs to run at once and virtually eliminated the possibility of one program crashing another. It is also the first Mac OS to include a command line, although it is never seen unless a separate "terminal" program is launched. However, since these new features put higher demands on system resources, Mac OS X is only officially supported on G3 and newer processors. (It runs poorly on many early G3 machines). Mac OS X has a compatibility layer for running older Mac applications, but compatibility is not 100%.

Mac OS Technologies

QuickDraw: the imaging model which first provided mass-market WYSIWYG.

Finder: the interface for browsing the filesystem and launching applications.

MultiFinder: the first version to support simultaneously running multiple apps.

Chooser: tool for accessing network resources (e.g., enabling AppleTalk).

ColorSync: technology for ensuring appropriate color matching.

Mac OS memory management: how the Mac managed RAM and virtual memory before the switch to UNIX.

PowerPC emulation of Motorola 68000: how the Mac handled the architectural transition from

CISC to RISC (see Mac 68K emulator).

Desk Accessories - small "helper" apps that could be run concurrently with any other app, prior to the advent of MultiFinder or System 7.

Solaris History

Solaris is the Unix-based operating system developed by Sun Microsystems, displays that company's ability to be innovative and flexible. Solaris, one could argue, is perpetually ahead of the curve in the computer world. Sun continually adapts to the changing computer environment, trying to anticipate where the computer world is going, and what will be needed next, and develops new versions of Solaris to take that into account.

Solaris was born in 1987 out of an alliance between AT&T and Sun Microsystems to combine the leading Unix versions (BSD, XENIX, and System V) into one operating system. Four years later in 1991, Sun replaced it's existing Unix operating system (SunOS 4) with one based on SVR4. This new OS, Solaris 2, contained many new advances, including use of the OpenWindows graphical user interface, NIS+, Open Network Computing (ONC) functionality, and was specially tuned for symmetric multiprocessing.

This kicked off Solaris' history of constant innovation, with new versions of Solaris being released almost annually over the next fifteen years. Sun was constantly striving to stay ahead of the curve, while at the same time adapting Solaris to the existing, constantly evolving wider computing world. The catalogue of innovations in the Solaris OS are too numerous to list here, but a few milestones are worth mentioning. Solar 2.5.1 in 1996 added CDE, the NFSv3 file system and NFS/TCP, expanded user and group IDs to 32 bits, and included support for the Macintosh PowerPC platform. Solaris 2.6 in 1997 introduced WebNFS file system, Kerberos 5 security encryption, and large file support to increase Solaris' internet performance.

Solaris 2.7 in 1998 (renamed just Solaris 7) included many new advances, such as native support for file system meta-data logging (UFS logging). It was also the first 64-bit release, which dramatically increased its performance, capacity, and scalability. Solaris 8 in 2000 took it a step further was the first OS to combine datecentre and dot-com requirements, offering support for IPv6 and IPSEC, Multipath I/O, and IPMP. Solaris 9 in 2002 saw the writing on the wall of the server market, dropped OpenWindows in favour of Linux compatibility, and added a Resource Manager, the Solaris Volume Manager, extended file attributes, and the iPlanet Directory Server.

Solaris 10, the current version, was released to the public in 2005 free of charge and with a host of new developments. The latest advances in the computing world are constantly being incorporated in new versions of Solaris 10 released every few months. To mention just a few, Solaris features more and more compatibility with Linux and IBM systems, has introduced the Java Desktop System based on GNOME, added Dynamic Tracing (Dtrace), NFSv4, and later the ZFS file system in 2006.

Also in 2006, Sun set up the OpenSolaris Project. Within the first year, the OpenSolaris community had grown to 14,000 members with 29 user groups globally, working on 31 active projects. Although displaying a deep commitment to open-source ideals, it also provides Sun with thousands of developers essentially working for free.

The development of the Solaris OS demonstrates Sun Microsystems' ability to be on the cutting edge of the computing world without losing touch with the current computing environment. Sun regularly releases new versions of Solaris incorporating the latest development in computer technology, yet also included more cross-platform compatibility and incorporating the advances of other systems. The OpenSolaris project is the ultimate display of these twin strengths-Sun has tapped into the creative energy of developers across the world and receives instant feedback about what their audience wants and needs. If all software companies took a lesson from Sun, imagine how exciting and responsive the industry could be.

Linux History

In order to know the popularity of linux, we need to travel back in time. In earlier days, computers were like a big house, even like the stadiums. So there was a big problem of size and portability. Not enough, the worst thing about computers is every computer had a different operating system. Software was always customized to serve a specific purpose, and software for one given system didn't run on another system. Being able to work with one system didn't automatically mean that you could work with another. It was difficult, both for the users and the system administrators. Also those computers were quiet expensive. Technologically the world was not quite that advanced, so they had to live with the size for another decade. In 1960, a team of developers in the Bell Labs laboratories started working on a solution or the software problem, to address these compatibility issues. They developed a new operating system, which was simple, elegant , written in C Programming language instead of Assebly language and most important is it can be able to recycle the code. The Bell Labs developers named their this project as " UNIX ".

Unix was developed with small piece of code which is named as kernel. This kernel is the only piece of code that needs to be adapted for every specific system and forms the base of the UNIX system. The operating system and all other functions were built around this kernel and written in a higher programming language, C. This language was especially developed for creating the UNIX system. Using this new technique, it was much easier to develop an operating system that could run on many different types of hardware. So this naturally affected the cost of Unix operating system, the vendors used to sell the software ten times than the original cost. The source code of Unix, once taught in universities courtesy of Bell Labs, was not published publicly. So developers tried to find out some solution to to provide an efficient solution to this problem.

A solution seemed to appear in form of MINIX. It was written from scratch by Andrew S. Tanenbaum, a US-born Dutch professor who wanted to each his students the inner workings of a real operating system. It was designed to run on the Intel 8086 microprocessors that had flooded the world market.

As an operating system, MINIX was not a superb one. But it had the advantage that the source code was available. Anyone who happened to get the book 'Operating Systems: Design and Implementation' by Tanenbaum could get hold of the 12,000 lines of code, written in C and assembly language. For the first time, an aspiring programmer or hacker could read the source codes of the operating system, which to that time the software vendors had guarded vigorously. A superb author, Tanenbaum captivated the brightest minds of computer science with the elaborate lively discussion of the art of creating a working operating system. Students of Computer Science all over the world worked hard over the book, reading through the codes to understand the very system that runs their computer.

And one of them was Linus Torvalds. Linus Torvalds was the second year student of Computer Science at the University of Helsinki and a self- taught hacker. MINIX was good, but still it was simply an operating system for the students, designed as a teaching tool rather than an industry strength one. At that time, programmers worldwide were greatly inspired by the GNU project by Richard Stallman, a software movement to provide free and quality software. In the world of Computers, Stallman started his awesome career in the famous Artificial Intelligence Laboratory at MIT, and during the mid and late seventies, created the Emacs editor.

In the early eighties, commercial software companies lured away much of the brilliant programmers of the AI lab, and negotiated stringent nondisclosure agreements to protect their secrets. But Stallman had a different vision. His idea was that unlike other products, software should be free from restrictions against copying or modification in order to make better and efficient computer programs. With his famous 1983 manifesto that declared the beginnings of the GNU project, he started a movement to create and distribute softwares that conveyed his philosophy (Incidentally, the name GNU is a recursive acronym which actually stands for 'GNU is Not Unix'). But to achieve this dream of ultimately creating a free operating system, he needed to create the tools first. So, beginning in 1984, Stallman started writing the GNU C Compiler (GCC), an amazing feat for an individual programmer. With his smart technical skills, he alone outclassed entire groups of programmers from commercial software vendors in creating GCC, considered as one of the most efficient and robust compilers ever created.

Linus himself didn't believe that his creation was going to be big enough to change computing forever. Linux version 0.01 was released by mid September 1991, and was put on the net. Enthusiasm gathered around this new kid on the block, and codes were downloaded, tested, tweaked, and returned to Linus. 0.02 came on October 5th.

Further Development

While Linux development, Linus faced some of the difficulties such as cross opinions with some people. E.g. Tanenbaum the great teacher who wrote the MINIX. He sent the letter to Linus as :-

�I still maintain the point that designing a monolithic kernel in 1991 is a fundamental error. Be thankful you are not my student. You would not get a high grade for such a design " Linus later admitted that it was the worst point of his development of Linux. Tanenbaum was certainly the famous professor, and anything he said certainly mattered. But he was wrong with Linux, for Linus was one stubborn guy who never like defeats. Although, Tanenbaum also remarked that �Linux is obsolete.� So very soon thousands of people form a community and all joined the camp. Powered by programs from the GNU project, Linux was ready for the actual showdown. It was licensed under GNU General Public License, thus ensuring that the source codes will be free for all to copy, study and to change. Students and computer programmers grabbed it.

Everyone tried and edited the source code and then it gives the start for commercial vendors to start their market. They compiled various software and distributed them with that operating system which people are familiar with. Red Hat, Debian gained more response from outside world. With the new graphical interface system like KDE, GNONE the linux becomes popular. The best thing today about Linux is it's powerful commands.

Rise of the Desktop Linux

What is the biggest complaint about Linux ??? That is it's Text mode. Many people get scared of seeing the command base interface which is not understandable. But if anyone starts learning the commands, it goes on interesting topics to learn new about the Operating System. Still now, very friendly GUI's are available for it's flexibility. Anyone can install the Linux without having the prior experience. Everything is well explanatory at the time of installation. Most distributions are also available in Live CD format, which the users can just put in their CD drives and boot without installing it to the hard drive, making Linux available to the newbies. The most important point about Linux is it's open source. So Computer users having low budget can have Linux and learn linux as it is free.

Linux's Logo - Penguin

The logo of Linux is Penguin. It's called as Tux in technological world. Rather Tux, as the penguin is lovingly called, symbolizes the carefree attitude of the total movement. This cute logo has a very interesting history. As put forward by Linus, initially no logo was selected for Linux. Once Linus went to the southern hemisphere on a vacation. There he encountered a penguin,not unlike the current logo of Linux. As he tried to pat it, the penguin bit his hand. This amusing incident led to the selection of a penguin as the logo of Linux sometime later.

Unix History

Since it began to escape from AT&T's Bell Laboratories in the early 1970's, the success of the UNIX operating system has led to many different versions: recipients of the (at that time free) UNIX system code all began developing their own different versions in their own, different, ways for use and sale. Universities, research institutes, government bodies and computer companies all began using the powerful UNIX system to develop many of the technologies which today are part of a UNIX system.

Computer aided design, manufacturing control systems, laboratory simulations, even the Internet itself, all began life with and because of UNIX systems. Today, without UNIX systems, the Internet would come to a screeching halt. Most telephone calls could not be made, electronic commerce would grind to a halt and there would have never been "Jurassic Park"!

By the late 1970's, a ripple effect had come into play. By now the under- and post-graduate students whose lab work had pioneered these new applications of technology were attaining management and decision-making positions inside the computer system suppliers and among its customers. And they wanted to continue using UNIX systems.

Soon all the large vendors, and many smaller ones, were marketing their own, diverging, versions of the UNIX system optimized for their own computer architectures and boasting many different strengths and features. Customers found that, although UNIX systems were available everywhere, they seldom were able to interwork or co-exist without significant investment of time and effort to make them work effectively. The trade mark UNIX was ubiquitous, but it was applied to a multitude of different, incompatible products.

In the early 1980's, the market for UNIX systems had grown enough to be noticed by industry analysts and researchers. Now the question was no longer "What is a UNIX system?" but "Is a UNIX system suitable for business and commerce?"

Throughout the early and mid-1980's, the debate about the strengths and weaknesses of UNIX systems raged, often fuelled by the utterances of the vendors themselves who sought to protect their profitable proprietary system sales by talking UNIX systems down. And, in an effort to further differentiate their competing UNIX system products, they kept developing and adding features of their own.

In 1984, another factor brought added attention to UNIX systems. A group of vendors concerned about the continuing encroachment into their markets and control of system interfaces by the larger companies, developed the concept of "open systems."

Open systems were those that would meet agreed specifications or standards. This resulted in the formation of X/Open Company Ltd whose remit was, and today in the guise of The Open Group remains, to define a comprehensive open systems environment. Open systems, they declared, would save on costs, attract a wider portfolio of applications and competition on equal terms. X/Open chose the UNIX system as the platform for the basis of open systems.

Although UNIX was still owned by AT&T, the company did little commercially with it until the mid-1980's. Then the spotlight of X/Open showed clearly that a single, standard version of the UNIX system would be in the wider interests of the industry and its customers. The question now was, "which version?".

In a move intended to unify the market in 1987, AT&T announced a pact with Sun Microsystems, the leading proponent of the Berkeley derived strain of UNIX. However, the rest of the industry viewed the development with considerable concern. Believing that their own markets were under threat they clubbed together to develop their own "new" open systems operating system. Their new organization was called the Open Software Foundation (OSF). In response to this, the AT&T/Sun faction formed UNIX International.

The ensuing "UNIX wars" divided the system vendors between these two camps clustered around the two dominant UNIX system technologies: AT&T's System V and the OSF system called OSF/1. In the meantime, X/Open Company held the center ground. It continued the process of standardizing the APIs necessary for an open operating system specification.

In addition, it looked at areas of the system beyond the operating system level where a standard approach would add value for supplier and customer alike, developing or adopting specifications for languages, database connectivity, networking and mainframe interworking. The results of this work were published in successive X/Open Portability Guides.

XPG 4 was released in October 1992. During this time, X/Open had put in place a brand program based on vendor guarantees and supported by testing. Since the publication of XPG4, X/Open has continued to broaden the scope of open systems specifications in line with market requirements. As the benefits of the X/Open brand became known and understood, many large organizations began using X/Open as the basis for system design and procurement. By 1993, over $7 billion had been spent on X/Open branded systems. By the start of 1997 that figure has risen to over $23 billion. To date, procurements referencing the Single UNIX Specification amount to over $5.2 billion.

In early 1993, AT&T sold it UNIX System Laboratories to Novell which was looking for a heavyweight operating system to link to its NetWare product range. At the same time, the company recognized that vesting control of the definition (specification) and trademark with a vendor-neutral organization would further facilitate the value of UNIX as a foundation of open systems. So the constituent parts of the UNIX System, previously owned by a single entity are now quite separate

In 1995 SCO bought the UNIX Systems business from Novell, and UNIX system source code and technology continues to be developed by SCO.

In 1995 X/Open introduced the UNIX 95 brand for computer systems guaranteed to meet the Single UNIX Specification. The Single UNIX Specification brand program has now achieved critical mass: vendors whose products have met the demanding criteria now account for the majority of UNIX systems by value.

For over ten years, since the inception of X/Open, UNIX had been closely linked with open systems. X/Open, now part of The Open Group, continues to develop and evolve the Single UNIX Specification and associated brand program on behalf of the IT community. The freeing of the specification of the interfaces from the technology is allowing many systems to support the UNIX philosophy of small, often simple tools , that can be combined in many ways to perform often complex tasks. The stability of the core interfaces preserves existing investment, and is allowing development of a rich set of software tools. The Open Source movement is building on this stable foundation and is creating a resurgence of enthusiasm for the UNIX philosophy. In many ways Open Source can be seen as the true delivery of Open Systems that will ensure it continues to go from strength to strength.

Operating System

What Is an Operating System?

An operating system (OS) is a core set of programs that control and supervise the hardware resources of a computer and provide services to other system software, application software, programmers, and users of a computer.

The OS gives the computer the instructions it needs to operate, telling it how to interact with hardware, other software, and the user.

The OS establishes a standard interface, or means of communication, between users and their computer systems.
When you power up a computer, you boot the system.
The booting procedure is so named because the computer "pulls itself up by its own bootstraps" (without the assistance of humans).
When booting the system,

First, a program in read-only memory (ROM) initializes the system and runs a system check to verify that the electronic components are operational and readies the computer for processing.
Next, the operating system is loaded to RAM, takes control of the system, and presents the user with a system prompt or a GUI screen full of options.

Operating System Parts

Operating systems are composed of two major parts:

control programs, and
service program.

Control programs manage computer hardware and resources.
The main program in most operating systems is the supervisor program.

A supervisor program is a control program that is known in some operating systems as the monitor, executive, or kernel.
The supervisor program is responsible for controlling all other OS programs as well as other system and application programs.
The supervisor program controls the activities of all of the hardware components of a computer.


Service programs are external OS programs that provides a service to the user or programmer of a computer.
They must be loaded separately because they are not automatically loaded when the operating system is loaded.
They perform routine but essential functions, such as formatting a disk for use and copying files from one location to another.

A Brief History of Computing - Operating Systems

1970

Development of UNIX operating system started. It was later released as C source code to aid portability, and subsequently versions are obtainable for many different computers, including the IBM PC. It and its clones (such as Linux) are still widely used on network and Internet servers. Originally developed by Ken Thomson and Dennis Ritchie.

1975

Unix marketed (see 1970).

1980 - October

Development of MS-DOS/PC-DOS began. Microsoft (known mainly for their programming languages) were commissioned to write the Operating System for the PC, Digital Research failed to get the contract (there is much legend as to the real reason for this). DR's Operating System, CP/M-86 was later shipped but it was actually easier to adapter older CP/M programs to DOS rather than CP/M-86, and CP/M-86 cost $495. As Microsoft didn't have an operating system to sell they bought Seattle Computer Product's 86-DOS which had been written by Tim Paterson earlier that year (86-DOS was also know as Q-DOS, Quick & Dirty Operating System, it was a more-or-less 16bit version of CP/M). The rights were actually bought in July 1981. It is reputed that IBM found over 300 bugs in the code when they subjected the operating system to their testing, and re-wrote much of the code.

Tim Paterson's DOS 1.0 was 4000 lines of assembler.

1981 - August 12

MS-DOS 1.0., PC-DOS 1.0.
Microsoft (known mainly for their programming languages) were commissioned by IBM to write the operating system, they bought a program called 86-DOS from Tim Paterson which was loosely based on CP/M 80. The final program from Microsoft was marketed by IBM as PC-DOS and by Microsoft as MS-DOS, collaboration on subsequent versions continued until version 5.0 in 1991.

Compared to modern versions of DOS version 1 was very basic, the most notable difference was the presence of just 1 directory, the root directory, on each disk. Subdirectories were not supported until version 2.0 (March, 1983).

MS-DOS (and PC-DOS) was the main operating system for all IBM-PC compatible computers until 1995 when Windows '95 began to take over the market, and Microsoft turned its back on MS-DOS (leaving MS-DOS 6.22 from 1993 as the last version written - although the DOS Shell in Windows '95 calls itself MS-DOS version 7.0, and has some improved features like long filename support). According to Microsoft, in 1994, MS-DOS was running on some 100 million computers world-wide.

1982 - March

MS-DOS 1.25, PC-DOS 1.1

1983 - March

MS-DOS 2.0, PC-DOS 2.0Introduced with the IBM XT this version included a UNIX style hierarchical sub-directory structure, and altered the way in which programs could load and access files on the disk.

1983 - May

MS-DOS 2.01

1983 - October

PC-DOS 2.1 (for PC Jr). Like the PC Jr this was not a great success and quickly disappeared from the market.

1983 - October

MS-DOS 2.11

1984 - August

MS-DOS 3.0, PC-DOS 3.0Released for the IBM AT, it supported larger hard disks as well as High Density (1.2 MB) 5?" floppy disks.

1985 - March

MS-DOS 3.1, PC-DOS 3.1This was the first version of DOS to provide network support, and provides some new functions to handle networking.

1985 - October

Version 2.25 included support for foreign character sets, and was marketed in the Far East.

1985 - November

Microsoft Windows Launched. Not really widely used until version 3, released in 1990, Windows required DOS to run and so was not a complete operating system (until Windows '95, released on August 21, 1995). It merely provided a G.U.I. similar to that of the Macintosh., in fact so similar that Apple tried to sue Microsoft for copying the 'look and feel' of their operating system. This court case was not dropped until August 1997.

1985 - December

MS-DOS 3.2, PC-DOS 3.2
This version was the first to support 3?" disks, although only the 720KB ones. Version 3.2 remained the standard version until 1987 when version 3.3 was released with the IBM PS/2.

1987

Microsoft Windows 2 released. It was more popular than the original version but it was nothing special mind you, Windows 3 (see 1990) was the first really useful version.

1987 - April

MS-DOS 3.3, PC-DOS 3.3Released with the IBM PS/2 this version included support for the High Density (1.44MB) 3?" disks. It also supported hard disk partitions, splitting a hard disk into 2 or more logical drives.

1987 - April

OS/2 Launched by Microsoft and IBM. A later enhancement, OS/2 Warp provided many of the 32-bit enhancements boasted by Windows '95 - but several years earlier, yet the product failed to dominate the market in the way Windows '95 did 8 year later.

1987 - October/November

Compaq DOS (CPQ-DOS) v3.31 released to cope with disk partitions >32MB. Used by some other OEMs, but not distributed by Microsoft.

1988 - July/August?

PC-DOS 4.0, MS-DOS 4.0

Version 3.4 - 4.x are confusing due to lack of correlation between IBM & Microsoft and also the USA & Europe. Several 'Internal Use only' versions were also produced.
This version reflected increases in hardware capabilities, it supported hard drives greater than 32 MB (up to 2 GB) and also EMS memory.

This version was not properly tested and was bug ridden, causing system crashes and loss of data. The original release was IBM's, but Microsoft's version 4.0 (in October) was no better and version 4.01 was released (in November) to correct this, then version 4.01a (in April 1989) as a further improvement. However many people could not trust this and reverted to version 3.3 while they waited for the complete re-write (version 5 - 3 years later). Beta's of Microsoft's version 4.0 were apparently shipped as early as '86 & '87.

1988 - November

MS-DOS 4.01, PC-DOS 4.01This corrected many of the bugs seen in version 4.0, but many users simply switched back to version 3.3 and waited for a properly re-written and fully tested version - which did not come until version 5 in June 1991. Support for disk partitions >32Mb.

1990 - May 22

Introduction of Windows 3.0 by Bill Gates & Microsoft. It is true multitasking (or pretends to be on computers less than an 80386, by operating in 'Real' mode) system. It maintained compatibility with MS-DOS, on an 80386 it even allows such programs to multitask - which they were not designed to do. This created a real threat to the Macintosh and despite a similar product, IBM's OS/2, it was very successful. Various improvements were made, versions 3.1, 3.11 - but the next major step did not come until Windows '95 in 1995 which relied much more heavily on the features of the 80386 and provided support for 32 bit applications.

1991 - June

MS-DOS 5.0, PC-DOS 5.0
In order to promote OS/2 Bill Gates took every opportunity after its release to say 'DOS is dead', however the development of DOS 5.0 lead to the permanent dropping of OS/2 development.

This version, after the mess of version 4, was properly tested through the distribution of Beta versions to over 7,500 users. This version included the ability to load device drivers and TSR programs above the 640KB boundary (into UMBs and the HMA), freeing more RAM for programs. This version marked the end of collaboration between Microsoft and IBM on DOS.

1991 - August

Linux is born with the following post to the Usenet Newsgroup comp.os.minix:

Hello everybody out there using minix-I'm doing a (free) operating system (just a hobby, won't bebig and professional like gnu) for 386(486) AT clones.

The post was by a Finnish college student, Linus Torvalds, and this hobby grew from these humble beginnings into one of the most widely used UNIX-like operating systems in the world today. It now runs on many different types of computer, including the Sun SPARC and the Compaq Alpha, as well as many ARM, MIPS, PowerPC and Motorola 68000 based computers.

In 1992, the GNU project (http://www.gnu.org/) adopted the Linux kernel for use on GNU systems while they waited for the development of their own (Hurd) kernel to be completed. The GNU project's aim is to provide a complete and free UNIX like operating system, combining the Linux or Hurd platform with the a complete suite of free software to run on it. In order to allow it to carry the GNU name, the Linux kernel copyright was changed to the GNU Public License Agreement (http://www.gnu.org/copyleft/gpl.html) on the 1st of February 1992.

1992 - April

Introduction of Windows 3.1

1993 - July 27

Windows NT 3.1, the first release of the Windows NT series, was released. Its name was chosen to match the current version of the 16 bit version of Microsoft Windows. NT contained a completely new 'kernel' at the core of the operating system, unlike Windows 3.x it was not based on top of MS-DOS. It was designed to be platform independant; original development was targetted at the Intel i860 processor but it was ported to MIPS and then to Intel's popular 80386 processor. The 'Win32' API was developed for Windows NT, providing a native 32 bit API that programmers used to the 16 bit versions of Microsoft Windows would be at home with.

1993 - December

MS-DOS 6.0. This included a Hard-Disk compression program called DoubleSpace, but a small computing company called 'Stac' claimed that DoubleSpace was partly a copy of their Compression Program, Stacker. After paying damages Microsoft withdrew DoubleSpace from MS-DOS 6.2, releasing a new program - DriveSpace - with MS-DOS version 6.22. In operation and programming interface DriveSpace remains virtually identical to DoubleSpace. MS-DOS 6.22 remains the last version of MS-DOS released, since Microsoft turned its efforts to Windows '95. Windows '95 (and later) DOS shell reports itself as DOS 7 - and includes a few enhancements, e.g. support for long filenames.

1994 - March 14

Linus Torvalds released version 1.0 of the Linux Kernel.

1994 - September

PC-DOS 6.3 Basically the same as version 5.0 this release by IBM included more bundled software, such as Stacker (the program that caused Microsoft so much embarrassment) and anti-virus software.

1994 - September 21

Microsoft released Windows NT 3.5. This included many features missing from the original 3.1 release, including support for compressed files and Netware compatibility.

1995 - March

Linus released Linux Kernel v1.2.0 (Linux'95).

1995 - May 30

The main feature of Windows NT 3.51 was a version supporting IBM's Power PC processor. Delays in the release of the processor meant delays in the release of Windows NT 3.51 (NT 3.51 only exists because the processor wasn't ready in time for NT 3.5). As the development team waited for the release of the processor they fixed bugs in the existing codebase. This made NT 3.51 reliable and therefore popular with customers.

1995 - August 21 [poss. 23]

Windows '95 was launched by Bill Gates & Microsoft. Unlike previous versions of Windows, Windows '95 is an entire operating system - it does not rely on MS-DOS (although some remnants of the old operating system still exist). Windows '95 was written specially for the 80386 and compatible computers to make 'full' use of its 32 bit processing and multitasking capabilities, and thus in some respects it is much more similar to Windows NT than Windows 3.x. Both Windows 95 and Windows NT provide the Win32 API for programmers, and when Windows NT 4 was released it had an almost identical user interface to Windows 95. Unfortunately, in order to maintain backwards compatibility, Windows 95 doesn't impose the same memory protection and security measures that NT does and so suffers from much worse stability, reliability and security. Despite being remarkable similar in function to OS/2 Warp (produced by IBM and Microsoft several years earlier, but marketed by IBM), Windows '95 has proved very popular.

1996

Windows '95 OSR2 (OEM System Release 2) was released - partly to fix bugs found in release 1 - but only to computer retailers for sale with new systems. There were actually two separated releases of Windows 95 OSR2 before the introduction of Windows '98, the second of which contained both USB and FAT32 support - the main selling points of Windows '98. FAT32 is a new filing system that provides support for disk paritions bigger than 2.1GB and is better at coping with large disks (especially in terms of wasted space).

1996 - June 9

Linux 2.0 released. 2.0 was a significant improvement over the earlier versions: it was the first to support multiple architectures (originally developed for the Intel 386 processor, it now supported the Digital Alpha and would very soon support Sun SPARC many others). It was also the first stable kernel to support SMP, kernel modules, and much more.

1996 - July 31

Windows NT 4.0 was released. The main feature was an update of the user interface to match Windows 95.

1998 - June 25

Microsoft released Windows '98. Some U.S. attorneys tried to block its release since the new O/S interfaces closely with other programs such as Microsoft Internet Explorer and so effectively closes the market of such software to other companies. Microsoft fought back with a letter to the White House suggesting that 26 of its industry allies said that a delay in the release of the new O/S could damage the U.S. economy. The main selling points of Windows '98 were its support for USB and its support for disk paritions greater than 2.1GB.

1999 - Jan 25

Linux Kernel 2.2.0 Released. The number of people running Linux is estimated at over 10million, making it an not only important operating system in the Unix world, but an increasingly important one in the PC world.

2000 - Feb 17

Offical Launch of Windows 2000 - Microsoft's replacement for Windows 95/98 and Windows NT. Claimed to be faster and more reliable than previous versions of Windows. It is actually a descendant of the NT series, and so the trade-off for increased reliability is that it won't run some old DOS-based games. To keep the home market happy Microsoft also released Windows ME, the newest member of the 95/98 series.

2001 - Jan 4

Linux kernel 2.4.0 released.

2001 - March 24

Apple released MacOS X. At its heart is `Darwin', an Open Source operaing system on FreeBSD. Using this MacOS X finally gives Mac users the stabilty benifits of a protected memory architecture along many other enhancements, such as preemptive multitasking. The BSD base also makes porting UNIX applications to MacOS easier and gives Mac users a fully featured command line interface alongside their GUI.

2001 - October 25

Microsoft released Windows XP - the latest version of their Windows operating system. Based on the NT series kernel, it was intended to bring together both the NT/2000 series and the Windows 95/98/ME series into one product. Of, course, it was originally hoped that this would happen with Windows 2000 but that failed. This failure was largely because of compatibility with some older applications, notably for home users problems with MS-DOS based games. Windows XP owes its success in part to some improvments in compability, and in part to time having passed - rendering much of the incompatible software obsolete anyway.

2003 - April 24

Windows Server 2003 is the latest incarnation of what began life as Windows NT. Windows Server 2003 is, as the name suggests, targetted at servers rather than workstations and home PCs, those are the realm of Windows XP. Security and reliability were key aims during the development and release of Windows Server 2003, critical if Windows is to replace the UNIX systems that serve many enterprises.

2003 - October 24

MacOS 10.3 continues to improve MacOS X, with major updates to 'Aqua' (the user interface) as well as performance improvements and new features.

2003 - December 17

Linux kernel 2.6.0 released. Many features from uClinux (designed for embedded microcontrollers) have been integrated, along with support for NUMA (used in large, multi-processor systems). an improved scheduler and scalability improvements help ensure Linux will maintain its reputation for running on everything from small embedded devices to large enterprise-class servers and even mainframes. As always support for new classes of hardware has been significantly improved.

� Copyright 1996-2005, Stephen White