Microsoft Timeline

Date and LaunchSoftware featuresHardware required
May 1964


Professors John Kemeny and Thomas Kurtz at Dartmouth College in New Hampshire write a high level "compile and run" language called Basic and place that listing (written in assembly language) in the public domain. It initially ran on Dartmouth's General Electric 225 mainframe computer.

GE-225 mainframe computer — running an interactive time-sharing operating system that Dartmouth College wrote for its students, the DTSS Dartmouth Time Sharing System.
Mar 1975

Microsoft Basic
program language

8-bit Microsoft Basic was the first Basic interpreter, written by Bill Gates & Paul Allen using a cross assembler program and an Intel 8080 emulator on a Digital PDP-10 minicomputer at Harvard. Runs in just 4kb ROM as Altair Basic.
Click here for an annotated disassembly.
The MITS Altair 8800 — an 8-bit micro-computer kit with Intel 8080   processor
Aug 1980

Microsoft Unix
its background
using source written in C.

16-bit Xenix, a multi-user, multi‑tasking PLATFORM, developed on Digital VAX and Digital PDP-11 computers. Licensed to OEMs by issuing assembly code relevant to the CPU. Also used for in-house development.Licenses for Intel, Tandy, Altos and SCO.
SCO release it for the IBM PC in Sep.1983.
Aug 1981

Microsoft DOS
operating system

16-bit MS-DOS PC-DOS as rebranded for IBM — a single-user, single-tasking personal operating system. Written as 86-DOS by Tim Paterson in assembly code using a Z80 microcomputer running CP/M. Requires just 64kb of RAM

Three programs load into memory:

  1. later known as IO.sys — runs DOS BIOS commands
  2. later known as MSDOS.sys — runs commands that read and write from the disk
  3. — its shell program with internal commands such as Dir, Copy, Del, Ren, Type and Cls.
Click here for its bootup sequence.

Click here for Assembly Code IBMBIO.COM version 1.0 and comments.

Click here for Assembly code and executables of versions 1.1 and 2.0
See the v11source folder for IO.asm, MSDOS.asm and COMMAND.asm.

16-bit IBM PC with 8-bit data bus on Intel 8088, up to 256kb RAM, an MDA video card with 4kb RAM, and 160kb 5¼" floppy disk(s). Great keyboard "feel", but awkward layout. Approx $AU3,500

Click here for background to its MBR Master Boot Record and here for its ROM BIOS its startup Firmware Interface

Click here for the original ROM BIOS Assembly Code Listings published between 1981 and 1985. The first listing includes its original font character set, each with an 8x8 (64 bit) pattern.

AMD — Applied Micro Designs became "second-source" manufacturer for Intel's patented x86 chip. With this guarantee, the IBM PC was launched with VisiCalc for spreadsheets for businesses, Microsoft Adventure for games, EDLIN for a built-in line editor, Easywriter for Word Processing (but fairly unpopular), Peachtree Accounting for businesses and dBASE II for database developers. For extra help built in, it came with a "Prt Scn" key that printed the screen image from the display buffer, three versions of Microsoft Basic: BASIC and BASICA (Advanced) on diskette, and Cassette BASIC in the ROM BIOS if no diskette loaded. In April 1982 Wordstar was ported to the PC and rapidly replaced Easywriter.

AT&T broken up, to go into computers.

In May, PC-DOS 1.1, then MS-DOS 1.25 added support for 360kb disks.
In July, Microsoft's in-house LAN runs Xenix for email.
IBM Compatibles — Compaq, Columbia on 8086 with 16-bit data bus & 320kb disks.

AT&T markets Unix, competes with Xenix, but owns the standard.

In January 1983, Lotus 123 was launched as a "killer" spreadsheet application with more functions and commands. Accountants everywhere encouraged businesses to learn its features.

In March, PC-DOS 2.0 and MS-DOS 2.0, supporting a 10mb hard drive, sub-directories (folders), pipes, redirection & other Unix-like features. Novell & Laplink launch using TSRs.

In May 1983, the Microsoft Mouse and Notepad were launched, followed by Microsoft Word in October 1983.
Note also, Microsoft's modern mouse with its scroll wheel did not appear until the Intellimouse in 1996.

16-bit IBM XT still 8-bit data bus but up to 640kb RAM, 10mb Hard Drive & 360kb 5¼" disks. Approx $AU8,000-$10,000

Click here for the PC's Master Boot Record for IBM PC DOS 2.00


Apple Mac's Debut
Microsoft talks to IBM regarding a new GUI, multi‑tasking platform

In Aug84, PC-DOS 3.0 and MS-DOS 3.0, supporting a 32mb hard drive. In Nov84, file-and-record locking controls added in MS-DOS 3.1. IBM authors NetBIOS using SMBs on IBM's Token Ring network. MS-Net launches on a dedicated server. Tries to compete with Novell. But not very well.

In January 1985 Word, with its graphical user interface, ported to the Apple Macintosh. In September 1985, a spreadsheet, Microsoft Excel, is written for the Mac. Not ported to Windows until late 1987.

16-bit IBM AT with 80286 processor, 1.2mb 5¼" disks, a 20mb Hard Drive, and an "enhanced" keyboard layout now in use everywhere. Approx $AU5,000-$8,500. Compatibles cheaper but compatibility issues arise.

The AT motherboard also included a battery backed Motorola real-time clock (RTC). The PC had required the user to set the clock manually. In addition to keeping the time, the RTC included 50 bytes of CMOS memory, for storing software-adjustable BIOS parameters.

Aug 1985

New OS Platform
Windows 32-bit Consumer GUI on a stable platform will take 16 years to arrive as Windows XP

The old 8088 / 8086 processors operated in Real Mode, able to address a maximum 1mb of memory, and ran just a single process. But Protected Mode, especially in the upcoming 32-bit 80386 enabled memory paging and safe multi‑tasking in up to 4gb RAM.So, Microsoft and IBM announce the Joint Development Agreement. IBM to build a proprietary Personal System/2 (PS/2). Microsoft to write its protected mode & networked Operating System/2 (OS/2) in C
Nov 1985

Microsoft Windows
Click here for extra history

16-bit Windows 1.0, mostly written in C, runs on MS-DOS 2 & 3 using 256kb - 512kb RAM. Offers multi‑tasking. But the memory maximum is still 1mb, and tasks need explicit programming to share processing time & memory. 
Mar 1986PC-DOS 3.2 with 3½" 720kb disk support 
Apr 1987PC-DOS 3.3, a major release with 3½" 1.44mb disk support and extended partitionsIBM's 16-bit computer is released in April 1987, the IBM Personal System/2 (PS/2) with 1.44mb 3½" disk, VGA screen & PS/2 mouse. Runs PC-DOS & Windows.
Nov 1987

Windows 2.0

16-bit Windows 2.0 runs on MS-DOS 3, still with 1mb limit, but now DDE (Dynamic Data Exchange). Lantastic P2P launch.
MS-DOS 3.31 for Compaq now supported Hard disk partitions over 32 MB
IBM's new operating system OS/2 v1.0.
Stays 16-bit for the PS/2 286. Text mode display.
3Com (Ethernet cards) write LAN Manager.
May 1988

Windows 2.1

16-bit Windows/286 & /386 with HMA access, V86-mode & NDIS 
Jul 1988MS-DOS 4.0 with DOS Shell File Manager and 32mb EMS 4.0 (Expanded Memory option)OS/2 v1.1 on PS/2 in Oct 88. Now GUI.
May 1990

Windows 3.0

16-bit Windows 3.0 runs on MS-DOS 3.1 also 4.0, 5.0, 6.0
Program Manager and now Protected memory support.
3Com bows out. System unravels when IBM insists Windows be dropped. Instead, Microsoft recasts OS/2 3.0 as Windows NT.
Oct 1990Microsoft Office (Word, Excel, Powerpoint) launched 
May 1991MS-DOS 5.0 was a major retail upgrade, DOS Editor, QBasic, Dir Sorting options and more 
Oct 1991Windows 3.00a multimedia extensions added 
Mar 1992

Windows 3.1

16-bit Windows 3.1, a major release with Apple TrueType fonts, OLE. In Oct92, 16-bit Windows for Workgroups (32-bit in Aug93). Samba launch.32-bit OS/2 2.0 in April 1992 by IBM solo.
Supports multitasking of DOS / Windows.
Mar 1993MS-DOS 6.0 included Double Space compression and further utilities. 
Apr 1993

Lots of New Names
COM Framework:
OLE Developers SDK,
Visual C++ and the MFC Wrapper Library

COM: Model for interprocess communication. Clients to access Components (as Objects) via a binary interface's unique GUID.
In 1994, introduced visual OLE controls. Then, in between VB4 & Visual Foxpro in 1995, and Visual J++ in Oct96, technology renamed ActiveX.
After the disagreements over the previous 8 years, the clean break with IBM offered Microsoft a new start, culminating in Windows XP, 8 years later. Click here for a humorous 1993 email, possibly from IBM.
Jul 1993

Microsoft Windows NT

Meanwhile, OS/2 3.0 is now 32-bit Windows NT
1993 NT 3.1,   1994 NT 3.5,   1995 NT 3.51
32-bit Server and Desktop.
NT stable but limited in hardware/ games.
Jun 1994MS-DOS 6.22 becomes last MS-DOS release with DriveSpace disk compression, following a legal injunction against DoubleSpace. 
Aug 1995

Windows 4.0

16 & 32-bit Windows 95, a major release running on MS-DOS 7, the first version of Windows to have a Start menu and a taskbar and support long file names, up to 255 characters.

MSDOS.sys was now merged into IO.sys as its one boot loader. It introduced PlugnPlay, which enabled users to easily install and use hardware devices without manual configuration, enforcing an industry standard interface with its DirectX standards for games and multimedia. And still included 16‑bit Win3.1 code to run popular 16-bit Windows games.

32-bit PC.
Easy to use though a little more unstable.
Says 4mb RAM but prefers 16 - 32mb

That same month Microsoft launched Internet Explorer 1.0, the first of Microsoft's large range of IE Browsers, initially part of an entertainment pack, Microsoft Plus!. It sold for $US49.99 with Microsoft paying programming royalties to Spyglass Mosaic, an offshoot of the University of Illinois, who had written the code for the browser.

On November 22 1995, Microsoft launched Internet Explorer 2.0, having numerous additional features, including Internet Mail, bundling it free with Windows 95 and Windows NT. It was subsequently ported to Apple Macintosh on April 23 1996, along with a 16-bit version that was written for Windows 3.1 users.


Jul 1996

Windows NT 4.0

32-bit Windows NT 4 with CIFS, a new name for SMB.Server and Desktop.


In October 1996, Microsoft named its object-oriented software interface ActiveX.
In January 1997, Microsoft Outlook launched as part of Office 97.
In May 1997, Microsoft launched its first server edition of ASP Active Server Pages (classic), somewhat similar to the open source software PHP.
In October 1997, Internet Mail was renamed to Outlook Express.
In December 1997, Hotmail purchased, succeeded in September 2012 by
In June 1998, Microsoft launched its first server edition of Terminal Server using PPTP, then in 2000 L2TP, enabling Internet based remote desktop access.


Jun 1998

Windows 4.1

16 & 32-bit Windows 98, a major release fixed many software errors in Winows 95. Still used MS-DOS 7 as boot loaderPC. Says 16mb RAM but prefers 64mb
Feb 2000

Windows NT 5.0

32-bit Windows 2000. Server edition now uses Active Directory.Server and Desktop.
Sep 2000

Windows 4.9

16 & 32-bit Windows Me using MS-DOS 8 as boot loader
Last of the 16-bit MS-DOS Kernels
PC. Says 32mb RAM but prefers 128mb
Oct 2001

Windows NT 5.1

32-bit Windows XP, a major release both stable and easy to use over the next decade. 64-bit edition also.
COM → .NET Framework with more secure Library
PC. Numerous hardware options
Says 64mb RAM but prefers 256mb
Apr 2003

Windows NT 5.2

32-bit Windows Server 2003. 64-bit edition also.Server
Nov 2006

Windows NT 6.0

32-bit Windows Vista with SMB2. 64-bit edition also.PC. Says 512mb RAM but prefers 1 - 2gb
Feb 2008

Windows NT 6.0

32-bit Windows Server 2008. 64-bit edition also.Server
Oct 2009

Windows NT 6.1

64-bit Windows 7, a major release. 32-bit edition also.

Microsoft Security Essentials included, Microsoft's first free anti-virus software.

PC. 1gb RAM 32-bit & 2gb RAM 64-bit
Oct 2009

Windows NT 6.1

64-bit Windows Server 2008 R2

In Feb 2010, first release of the Microsoft Azure cloud computing service through Microsoft-managed data centres.
Click here for a recent review by Datamation.

HighUsage Server


In October 2010, Office 365 announced as "an always-up-to-date cloud service" for Microsoft Office. Initially a beta version for business customers, its official launch came in April 2011. Extended to general consumers in 2013, with subscription sales passing conventional license sales in 2017. In 2020, Office 365 was rebranded as Microsoft 365.

In May 2011, Skype purchased.
Skype launched originally in 2003, a fore-runner of Zoom. It ran on a centralized login server, Kazaa-like supernodes, with localized "buddy-lists". In 2006 with 136 million users, it linked to wholesale international telephone carriers UK Cable & Wireless (Vodafone), US iBasis, and Level 3 (Lumen).
In 2013 Microsoft used the technology to replace its instant messaging service, which had launched in 1999 as MSN Messenger, and in 2005 had become Windows Live Messenger.
By 2017 the Skype service had shifted from a peer-to-peer to a central server based system.


Sep 2012

Windows NT 6.2

64-bit Windows Server 2012Server
Oct 2012

Windows NT 6.2

64-bit Windows 8. 32-bit edition also.

Windows Defender released as Microsoft's new built-in anti-virus software, achieving top ranking in comparison with other anti-virus software by time of Windows 10.

PC. 1gb RAM 32-bit & 2gb RAM 64-bit but prefers 4gb
Oct 2013

Windows NT 6.3

64-bit Windows 8.1. 32-bit edition also.PC. Memory requirements lowered to 1 GB of RAM on all devices
Jul 2015

Windows NT 10.0

64-bit Windows 10, a major release. 32-bit edition also.

Windows Store now includes an app that streams all Aussie Free-to-Air TV channels
Click here

PC. 1gb RAM 32-bit & 2gb RAM 64-bit but prefers 4gb
Oct 2016

Windows NT 10.0

64-bit Windows Server 2016Server
Oct 2018

Windows NT 10.0

64-bit Windows Server 2019Server
Oct 2021

Windows NT 10.0

64-bit Windows 11 with a free upgrade for Windows 10 users.
Click here for further details and hardware specs.
PC. 4gb RAM
Oct 2021

Windows NT 10.0

64-bit Windows Server 2022Server


Making System Repairs to Windows 10 and 11

  1. CHKDSK (Check Disk or Scan disk)
    CHKDSK scans your drive to find bad sectors and tries to fix errors in the file system. It can take anywhere between one minute to over two hours or more, depending on the type of storage or the size of the disk.
    1. Open File Explorer on your Windows machine. You can use the keyboard shortcut Windows + E for the same.
    2. Click on This PC and Right Click on the drive where you want to run CHKDSK.
    3. Click on Properties > Tools > Error Checking > Check

  2. SFC (System File Checker)
    SFC checks for missing important files of your Windows operating system and restores them from the cache.
    1. Open Command Prompt as administrator by searching for CMD in the Windows search bar, Right Click on it and choose Run as administrator option.
    2. For a full scan and automatic repair of corrupted files, type
      sfc /scannow and press the Enter key. Takes between 5 to 10 minutes.

  3. DISM (Deployment Image Servicing and Management)
    DISM is an advanced command-line tool that directly deals with faulty Windows images and repairs them by downloading actual replacement files from Windows' online servers.
    Click here for further details. Takes about 15-20 minutes.

Some old notes re Windows Vista Takeup (long long ago)

With respect to yearly sales of Windows, Apple and Linux, research by technology analyst Gartner in 2006 showed current market share and their predictions of market share through to 2010 to be as follows:

The Australian
December 5th 2006

Windows Vista Business0.0%4.2%15.3%28%39.1%
Windows Vista Home0.0%4.9%14%22%28.6%
Windows 2000 Professional14.9%9.1%4.8%2.5%1.4%
Windows XP Professional44.5%47%39.7%28.6%18%
Windows XP Home29.8%28.6%21.6%14.5%8.5%
Apple Mac OS2.5%2.4%2.4%2.4%2.4%

Windows XP looks like being around for some time to come - much to Microsoft's disappointment - given how much time - and money they've spent on Vista.

Addendum in 2014

The takeup rate for Windows Vista can be seen to have been much lower than Gartner estimated. In June 2014, Windows XP accounted for about 25% of market share, with Windows Vista on just 3%, Windows 7 on 50% and Windows 8 on 13%.

In 2013, about 315 million PCs were sold globally, with 91% running some version of Microsoft Windows, 7% running Mac OS X, and the rest on Linux and other systems.
Click here to see recent percentages also a breakdown of operating systems used in web servers, mobile devices (i.e. smartphones and tablets) and mainframes.

In May 2014, Microsoft's increasing lack of openness within Windows 8 meant that the Chinese Government banned Windows 8 from all Chinese government purchases. They had had considerable access to Windows 7's source code.

As part of efforts to "re-engage" with users in China, Microsoft announced that it would partner with Qihoo and Tencent to help promote and distribute Windows 10 in China, and that Chinese PC maker Lenovo would provide assistance at its service centers and retail outlets for helping users upgrade to Windows 10.


On December 2, 2014 8:05 AM "Stephen Williamson" wrote:

Subject: Microsoft and those numbers

Hi Jackie

Found this Wiki page

As it says, Windows 9x is the generic term referring to the series of Microsoft Windows computer operating systems produced from 1995 to 2000 i.e.
Windows 95, Windows 98, Windows ME (with their internal release versions known as 4.0, 4.1 and 4.9)
Windows 2000 and Windows XP were NT 5.0 and NT 5.1, and Windows Vista became NT 6.0

And according to this page Microsoft have been referring to their next version since Windows 8 as "Threshold".

It was only speculated that it would be branded Windows 9 on its release, but I guess that might have been a bit ambiguous when referring to those earlier versions. On September 30, 2014 it was announced that "Threshold" would be called "Windows 10". I guess it saves that ambiguity, but, like happened with yourself, it's still only going to cause more questions about "What happened to Windows 9?"

love Steve


Some personal reflections

Apple (click for key dates) retain proprietary rights by always writing their own software and building their own machines. They cater to a niche (and loyal) market worldwide, historically in desktop publishing, graphics, sound, and research i.e. cutting edge development.

Linux, on the other hand, is an open source operating system, based on Unix-like commands, and originally written in 1991 by Linus Torvalds. Accordingly, companies can only claim ownership rights to their version of the operating system, as each one carves out its own niche.

For all its difficulties, the biggest strength of Microsoft through the years, I believe, has been continuity of data service: i.e. numerous software packages with accompanying file structures written with earlier versions of MS Windows have been regularly supported in later versions of Windows - at times for years into the future. It is this continuity that provides assurance to the vast majority of business companies and individuals who rely on Microsoft, and is doubtless a lesson Microsoft learned from the original computer companies: IBM, NCR, etc.

This continuity of service, incidentally, many times does not apply to old hardware. This was the source of a major difficulty between Microsoft and IBM during that period 1985-1990, given the enormous investment that businesses had made, and were still making, in 16-bit IBM 80286 and older XT computers, expecting ongoing support. Not so much an issue to Microsoft of course, who don't sell business computers. But coming back to today, for this reason it has been recommended that users only ever upgrade their version of MS Windows when purchasing a new computer — or when the computer they own is less than 12 months old.

Windows 11 Upgrade launched in 2021

According to Microsoft, there were 1.3 billion Windows users in 2021.
Windows 11 was announced on Thursday June 24, and launched on Tuesday October 5 2021. New PCs will get the upgrade first, and all compatible devices are expected to receive it by mid-2022, depending on device age and hardware.

Some early reviews
One big change is that Windows 11 will allow the operator to launch Video Chat Teams from the taskbar.
Click the Teams icon to launch a Chat tool. It will let you choose if you want to message, text, voice or video call one of your contacts.
Virtual desktops will now run "more seamlessly".
Android Apps will also be installable (more seamlessly).
A free upgrade will be available for Windows 10 users click here for a link to see if your device is compatible.

Basic Windows 11 Requirements
Processor1GHz or faster with 2 or more cores on a compatible 64-bit processor or system on a chip
Storage64GB or larger storage device
System firmwareUEFI, Secure Boot capable
TPMTrusted Platform Module (TPM) version 2.0
Graphics cardCompatible with DirectX 12 or later with WDDM 2.0 driver
DisplayHD (720p) display greater than 9 inches diagonally, 8 bits per color channel

** End of article