A Brief History of Computing
- Operating Systems

© Copyright 1996-2005, Stephen White

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Translated to Serbo-Croatian by Anja Skrba from Webhostinggeeks.com

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 2.0
Introduced 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 3.0
Released 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 3.1
This 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 3.3
Released 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 4.01
This 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 be
big 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 1996-2004, Stephen White My homepage - email:swhite@ox.compsoc.net