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.

Apple deliberately played up the existence of the operating system in the early years of the Macintosh 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. Apple wanted Macintosh to be portrayed as a system “for the rest of us”.

Microsoft Windows

Microsoft Windows is a range of operating environments for personal computers and servers. The range was first introduced by Microsoft in 1985 to counter Apple’s new system; the Apple Macintosh, which used a graphical user interface (GUI). Microsoft Windows eventually came to dominate the world personal computer market with a market share estimated to be around 95% for desktop personal computers. All recent versions of Windows are fully-fledged operating systems. Windows is proprietary closed source software: Microsoft Corporation owns the software’s copyright and controls its distribution.

Windows was developed for IBM PC-compatible computers (these were based on Intel x86 architecture), and today, almost all versions of Windows are made for this hardware-platform (although Windows NT was written as a cross-platform system for Intel and MIPS processors, and later appeared on the PowerPC and DEC Alpha architectures). The popularity of Windows made Intel CPUs more popular and vice versa. In fact, the term Wintel became used to describe PC-compatible computers running a version of Windows.

FreeBSD is developed together as an entire operating system. The kernel, all of the expected userland utilities such as the shell and the device drivers are held in the same source code revision tracking tree (CVS). This is in contrast to Linux, a similar and more well known free Unix-clone, which is developed as a kernel by one group, userland utilities by others such as the GNU project, and put together with applications into distributions that package all the parts together by others. As an operating system, FreeBSD is generally regarded as being quite reliable and robust, and of the operating systems that accurately report uptime remotely
FreeBSD is the only free operating system listed in Netcraft’s list of the 50 web servers with longest uptime. However long uptime also indicates that no kernel security fixes are installed, as installing a new kernel requires a reboot and resets the uptime counter of the system.

License

FreeBSD is released under the BSD License, which allows everyone to use and redistribute FreeBSD as they wish, as long as they do not remove the copyright notice and the BSD license itself — which does not prohibit re-distribution under another license. There are also some parts under the GPL or the LGPL, such as gcc and gzip.

Linux

Linux is one of the most prominent examples of free software and of open-source development: unlike other major ‘closed-source’ operating systems

Initially, Linux was primarily developed and used by individual enthusiasts. Since then, Linux has gained the support of major corporations such as IBM, Hewlett-Packard and Novell for use in servers and is beginning to make inroads into the desktop market. Proponents and analysts attribute this success to its vendor independence, low cost, security, and reliability.

Linux was originally developed for Intel 386 microprocessors and now supports all popular computer architectures (and several obscure ones). It is deployed in applications ranging from personal computers to supercomputers and embedded systems such as mobile phones and personal video recorders.

History
The Linux kernel was initially written as a hobby by Finnish university student Linus Torvalds while attending the University of Helsinki. Torvalds originally used Minix on his computer, a simplified kernel written by Andrew Tanenbaum for teaching operating system design. However, Tanenbaum did not support extensions to his operating system, leading Torvalds to write a replacement for Minix. Linux started out as a terminal emulator written in IA-32 assembler and C which was compiled into binary form and booted from a floppy disk so that it would run outside of any operating system. The terminal emulator was running two threads: one for sending and one for receiving characters from the serial port. When Linus needed to write and read files to disk, this task-switching terminal emulator was extended with an entire filesystem handler, and after that gradually evolved into an entire operating system targeted at POSIX-compliance. Linus implemented enough POSIX system calls to make Linux run the Bash shell and after this bootstrapping procedure the development rapidly sped up. Although a running Minix system was originally necessary in order to configure, compile, install and run Linux, the Linux system quickly surpassed Minix in functionality and was soon able to boot on its own and compile its own source code.

Linus Torvalds, creator of the Linux kernelThe first version of the Linux kernel was released to the Internet in September 1991, with the second version following shortly thereafter in October [1]. Since then, thousands of developers around the world have participated in the project. Eric S. Raymond’s essay The Cathedral and the Bazaar discusses the development model of the Linux kernel and similar software.

The history of the Linux kernel is closely tied to that of GNU, a prominent free-software project led by Richard Stallman. The GNU project was announced in 1983 for the purpose of developing a complete Unix-like operating system, including software development tools and user application programs, composed entirely of free software. By the release of the first version of the Linux kernel, the GNU project had produced all the necessary components of this system except the kernel. Torvalds and other early Linux-kernel developers adapted their kernel to work with the GNU components and user space programs to create a fully functional operating system. The Linux kernel and operating system are licensed under the GNU General Public License (GPL) which requires that all source code modifications and derived works also be licensed under the GPL, which is generally referred to as a “share and share-alike” license. In 1997 Linus Torvalds stated, “Making Linux GPL’d was definitely the best thing I ever did.”

Tux the penguin is the logo and mascot of Linux (though there are other less common representations; see OS-tan). The name “Linux” was coined, not by Torvalds, but by Ari Lemmke, administrator at ftp.funet.fi, who named the FTP directory from which it was first available [3]. The Linux trademark (SN: 1916230) is owned by Linus Torvalds, registered for “Computer operating system software to facilitate computer use and operation.” The licensing of the trademark is now handled by the Linux Mark Institute.