What's DOS

DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.

Related systems include MS-DOS, PC-DOS, DR-DOS, FreeDOS, PTS-DOS, ROM-DOS, Caldera DOS, Novell DOS and several others.

In spite of the common usage, none of these systems were simply named "DOS" (a name given only to an unrelated IBM mainframe operating system in the 1960s). A number of unrelated, non-x86 microcomputer disk operating systems had "DOS" in their name, and are often referred to simply as "DOS" when discussing machines that use them (e.g. AmigaDOS, AMSDOS, ANDOS, Apple DOS, Atari DOS, Commodore DOS, CSI-DOS, ProDOS, and TRS-DOS). While providing many of the same operating system functions for their respective computer systems, programs running under any one of these operating systems would not run under others.

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All MS-DOS-type operating systems run on machines with the Intel x86 or compatible CPUs, mainly the IBM PC and compatibles. Machine-dependent versions of MS-DOS were produced for many non-IBM-compatible x86-based machines, with variations from relabelling of the Microsoft distribution under the manufacturer's name, to versions specifically designed to work with non-IBM-PC-compatible hardware. DOS-C's predecessor DOS/NT ran on Motorola 68000 CPU's.

DOS is a single-user, single-task operating system with basic kernel functions that are non-reentrant: only one program at a time can use them. There is an exception with Terminate and Stay Resident (TSR) programs, and some TSRs can allow multitasking. However, there is still a problem with the non-reentrant kernel: once a process calls a service inside of operating system kernel (system call), it must not be interrupted with another process calling system call, until the first call is finished.

The DOS kernel provides various functions for programs (an application program interface), like displaying characters on-screen, reading a character from the keyboard, accessing disk files and more.

DOS by default provides a primitive ability for shell scripting, via batch files (with the filename extension .BAT). These are text files that can be created in any text editor. They are executed in the same fashion as compiled programs, and run each line of the batch file as a command. Batch files can also make use of several internal commands, such as goto and conditional statements. gosub and simple arithmetic is supported in some third-party shells but can also be faked via strange workarounds; however, no real form of programming is usually enabled.

The operating system offers a hardware abstraction layer that allows development of character-based applications, but not for accessing most of the hardware, such as graphics cards, printers, or mice. This required programmers to access the hardware directly, usually resulting in each application having its own set of device drivers for each hardware peripheral. Hardware manufacturers would release specifications to ensure device drivers for popular applications were available.

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Origins:

IBM PC-DOS (and the separately sold MS-DOS, which was licensed therefrom) and its predecessor, 86-DOS, were loosely inspired by Digital Research's CP/M (Control Program / [for] Microcomputers), which was the dominant disk operating system for 8-bit Intel 8080 and Zilog Z80 based microcomputers. PC-DOS ran on 8088 (16-bit) and above.

When IBM introduced their first microcomputer in 1980, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates (possibly believing that Microsoft owned CP/M due to the Microsoft Z-80 SoftCard, which allowed CP/M to run on an Apple II). IBM was sent to Digital Research, and a meeting was set up. However, the initial negotiations for the use of CP/M broke down—Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license, and to change the name to "PC DOS". DR founder Gary Kildall refused, and IBM withdrew.

IBM again approached Bill Gates. Gates in turn approached Seattle Computer Products. There, programmer Tim Paterson had developed a variant of CP/M-80, intended as an internal product for testing SCP's new 16-bit Intel 8086 CPU card for the S-100 bus. The system was initially named "QDOS" (Quick and Dirty Operating System), before being made commercially available as 86-DOS. Microsoft purchased 86-DOS, allegedly for $50,000. This became Microsoft Disk Operating System, MS-DOS, introduced in 1981.

Microsoft also licensed their system to multiple computer companies, who supplied MS-DOS for their own hardware, sometimes under their own names. Microsoft later required the use of the MS-DOS name, with the exception of the IBM variant. IBM continued to develop their version, PC DOS, for the IBM PC. Digital Research became aware that an operating system similar to CP/M was being sold by IBM (under the same name that IBM insisted upon for CP/M), and threatened legal action. IBM responded by offering an agreement: they would give PC consumers a choice of PC DOS or CP/M-86, Kildall's 8086 version. Side-by-side, CP/M cost almost $200 more than PC DOS, and sales were low. CP/M faded, with MS-DOS and PC DOS becoming the marketed operating system for PCs and PC compatibles.

Digital Research attempted to regain the market lost from CP/M-86; initially with DOS Plus, and later with DR-DOS (both compatible with both MS-DOS and CP/M-86 software). Digital Research was bought by Novell, and DR DOS became Novell DOS 7; later, it was part of Caldera Systems (under the names OpenDOS and DR DOS 7), Lineo, and DeviceLogics.

Microsoft and IBM later had a series of disagreements over two successor operating systems to DOS - Microsoft's Windows and IBM's OS/2.[18] They split development of their DOS systems as a result. MS-DOS was partially transformed into Windows; the last version of PC DOS was PC DOS 2000, released in 1998.

The FreeDOS project began June 26, 1994, when Microsoft announced it would no longer sell or support MS-DOS. Jim Hall then posted a manifesto proposing the development of an open-source replacement. Within a few weeks, other programmers including Pat Villani and Tim Norman joined the project. A kernel, the command.com command line interpreter (shell) and core utilities were created by pooling code they had written or found available. There were several official pre-release distributions of FreeDOS before the FreeDOS 1.0 distribution was released on September 3, 2006. Made available under the GNU General Public License (GPL), FreeDOS does not require license fees or royalties.

After DOS M$ moved to Windows 1

ersion 1.02, released in May 1986, was international and had editions in several European languages. Version 1.03, released in August 1986, was for the US- and international market, with enhancements making it consistent with the international release. It included drivers for European keyboards and additional screen and printer drivers. Version 1.04, released in April 1987, added support for the VGA graphics adapters of the new IBM PS/2 computers.[citation needed] At the same time, Microsoft and IBM announced the introduction of OS/2 and its graphical OS/2 Presentation Manager, which were supposed to ultimately replace both MS-DOS and Windows.

Windows 1.0 was superseded by Windows 2.0 in November 1987, but supported by Microsoft for sixteen years, until 31 December 2001.
[edit] Competition

The history of Windows dates back to September 1981, when the project named "Interface Manager" was started. It was first presented to the public on 10 November 1983, renamed to "Microsoft Windows"; the two years of delay before release led to charges that it was "vaporware". The initially announced version of Windows had features so much resembling the Macintosh interface that Microsoft had to change many of them: overlapping windows, although supported by the GUI engine, weren't allowed for exactly this reason. The announcement of Windows' imminent arrival in 1985 probably did not help the sales of VisiCorp's VisiOn environment which debuted at the same time. However, even when finally released, Windows 1.0 aroused little interest.

Another GUI for the PC platform at the time was GEM. It used more aspects from the Macintosh GUI, for example the trash can concept (which Microsoft would later employ in future Windows releases) and more generally the desktop interaction. GEM was eventually used as the standard GUI for the Atari's ST range of 68k-based computers, which were sometimes referred to as Jackintoshes (the company being run by Jack Tramiel). GEM was also included in the Amstrad PC1512, probably the first 8086 based PC targeted at the home consumer and sold alongside TV's and washing machines at appliance stores. GEM's resemblance to the Mac OS later caused legal trouble for the manufacturer, Digital Research, who was obliged to seriously cripple the desktop's appearance and functionality (applications were not affected).

GEM was relying on multitasking of the OS under it (non-existing in DOS on that time), so users had to close one program in order to run another one. Collections of related programs, like GEM Draw, had confusing File menu items like Close (to Edit) to facilitate switching.

An alternative multitasker released shortly before was DESQview, a successor of IBM's failed TopView from 1984. It did not have graphical capabilities initially, but is able to multitask DOS applications in windows as long as they are well-behaved or have a specially written "loader" to fix them on the fly.

Windows 1.0 market share grew very slowly. Early Windows versions of Microsoft Excel and other Windows applications were bundled with a runtime version of Windows, presumably to both increase sales of the applications and allow users to "test drive" Windows at no additional cost.

The Macintosh remained the platform of choice especially for high-end graphics and desktop publishing (DTP). Although Aldus PageMaker shipped in January 1987 with a Windows executable, it remained a curiosity due to poor support relative to the Mac version, and a steep $795 price tag.

Other shell programs for MS-DOS include Norton Commander, PC Tools, XTree. DOS Shell, and DOS Menu (in MS-DOS version 4.0). These applications attempted to be organizational and menu-driven tools, and did not try at all to be a 'desktop' shell.
[edit] Features

Windows 1.0 offers limited multitasking of existing MS-DOS programs and concentrates on creating an interaction paradigm (cf. message loop), an execution model and a stable API for native programs for the future. Due to Microsoft's extensive support for backward compatibility, it is not only possible to execute Windows 1.0 binary programs on current versions of Windows to a large extent, but also to recompile their source code into an equally functional "modern" application with just limited modifications[2].

Windows 1.0 is often regarded as a "front-end to the MS-DOS operating system", a description which has also been applied to subsequent versions of Windows. Windows 1.0 is an MS-DOS program. Windows 1.0 programs can call MS-DOS functions, and GUI programs are run from .exe files just like MS-DOS programs. However, Windows .exe files had their own "new executable" (NE) file format, which only Windows could process and which, for example, allowed demand-loading of code and data. Applications were supposed to handle memory only through Windows' own memory management system, which implemented a software-based virtual memory scheme allowing for applications larger than available RAM.

Because graphics support in MS-DOS is extremely limited, MS-DOS applications have to go to the bare hardware (or sometimes just to the BIOS) to get work done. Therefore, Windows 1.0 included original device drivers for video cards, a mouse, keyboards, printers and serial communications, and applications were supposed to only invoke APIs built upon these drivers. However, this extended to other APIs such as file system management functions. In this sense, Windows 1.0 was designed to be extended into a full-fledged operating system, rather than being just a graphics environment used by applications. Indeed, Windows 1.0 is a "DOS front-end" and cannot operate without a DOS environment (it uses, for example, the file-handling functions provided by DOS.) The level of replacement increases in subsequent versions.

The system requirements for Windows 1.01 constituted CGA/Hercules/EGA (listed as "Monochrome or color monitor"), MS-DOS 2.0, 256 kB of memory or greater, and two double-sided disk drives or a hard drive[3].

Windows 1.0 runs a shell program known as MS-DOS Executive. Other supplied programs are Calculator, Calendar, Cardfile, Clipboard viewer, Clock, Control Panel, Notepad, Paint, Reversi, Terminal, and Write.

Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only dialog boxes can appear over other windows.

Windows 1.0 executables, while having the same .exe extension and initial file header as MS-DOS programs, do not contain the so-called MS-DOS stub which prints the "This program requires Microsoft Windows" message and exits when the program is run outside of Windows. Instead, the file header was formatted in such a way as to make DOS reject the executable with a "program too large to fit in memory" error message.

From the beginning, Windows was intended to multitask programs (although this originally only applied to native applications and for many versions the multitasking was co-operative, rather than preemptive).

Pre-release versions had menus at the bottom of windows, as it was used in Microsoft applications, such as Word and Multiplan of that era; however, this was changed before the first release.

Windows 2 had few:

The first Windows versions of Microsoft Word and Microsoft Excel ran on Windows 2.0. Third-party developer support for Windows increased substantially with this version (some shipped the Windows Runtime software with their applications, for customers who had not purchased the full version of Windows). However, most developers still maintained DOS versions of their applications, as Windows users were still a distinct minority of their market.

Applications shipping with Windows 2.0:

* CALC.EXE
* CALENDAR.EXE
* CARDFILE.EXE
* CLIPBRD.EXE
* CLOCK.EXE
* CONTROL.EXE
* CVTPAINT.EXE
* MSDOS.EXE
* MSDOSD.EXE
* NOTEPAD.EXE
* PAINT.EXE
* REVERSI.EXE
* TERMINAL.EXE
* WRITE.EXE

The most notable Windows GUI was Windows 3.11

Windows 3.0 succeeded Windows 2.1x and included a significantly revamped user interface as well as technical improvements to make better use of the memory management capabilities of Intel's 80286 and 80386 processors. Text-mode programs written for MS-DOS could be run within a window (a feature previously available in a more limited form with Windows/386 2.1), making the system usable as a crude multitasking base for legacy programs. However, this was of limited use for the home market, where most games and entertainment programs continued to require raw DOS access.

The MS-DOS Executive file manager/program launcher was replaced with the icon-based Program Manager and the list-based File Manager, thereby simplifying the launching of applications. The MS-DOS Executive is also included as an alternative to these. The Control Panel, previously available as a standard-looking applet, was re-modeled after the one in Mac OS. It centralized system settings, including limited control over the color scheme of the interface.

A number of simple applications were included, such as the text editor Notepad and the word processor Write (both inherited from earlier versions of Windows), a macro recorder (new; later dropped), the paint program Paintbrush (inherited but substantially improved), and a calculator (also inherited). Also, the earlier Reversi game was complemented with the card game Solitaire.

The Windows icons and graphics were redesigned to take advantage of VGA's 16-color mode. Earlier versions only supported eight colors though could run on monochrome video adapters. Windows 3.0 also allowed the user to use a 256 color video adapter, whereas previous versions only supported 16 colors.

Windows 3.0 includes a Protected/Enhanced mode which allows Windows applications to use more memory in a more painless manner than their DOS counterparts could. It can run in any of Real, Standard, or 386 Enhanced modes, and is compatible with any Intel processor from the 8086/8088 up to 80286 and 80386. Windows 3.0 tries to auto detect which mode to run in, although it can be forced to run in a specific mode using the switches: /r (real mode), /s ("standard" 286 protected mode) and /3 (386 enhanced protected mode) respectively. Due to this backward compatibility of the whole system, Windows 3.0 applications also must be compiled for 16-bit mode, without ever using the full 32-bit capabilities of the 386 CPU.

This was the first version to run Windows programs in protected mode, although the 386 enhanced mode kernel was an enhanced version of the protected mode kernel for Windows/286.

A "multimedia" version, Windows 3.0 with Multimedia Extensions 1.0, was released later in 1991. This was bundled with "multimedia upgrade kits", comprising a CD-ROM drive and a sound card, such as the Creative Labs Sound Blaster Pro. This version was the precursor to the multimedia features available in Windows 3.1 and later, and was part of Microsoft's specification for the Multimedia PC.

Windows 3.0 was the last version of Windows to advertise 100% compatibility with older Windows applications.[1] This only applies to real mode.
A boxed copy of Windows 3.0 in the original shrinkwrap. This boxed copy includes 3.5" floppies (720K version) for DOS systems.
[edit] System requirements

The official system requirements for Windows 3.0:

* 8086/8088 processor or better
* 384K of free conventional memory (real mode, protected modes require more)[2]
* Hard disk with 6-7MB of free space
* CGA/EGA/VGA/Hercules/8514/A graphics and an appropriate and compatible monitor
* MS-DOS version 3.1 or higher[3]

Also, a Microsoft-compatible mouse is recommended.
[edit] Memory modes

Windows 3.0 was the only version of Windows that could be run in three different memory modes:

* Real mode, intended for older computers with a CPU below Intel 80286, and corresponding to its real mode;
* Standard mode, intended for computers with an 80286 processor, and corresponding to its protected mode;
* 386 Enhanced mode, intended for newer computers with an Intel 80386 processor or above, and corresponding to its protected mode and virtual 8086 mode.

Real mode primarily existed as a way to run Windows 2.x applications. It was removed in Windows 3.1x. Almost all applications designed for Windows 3.0 had to be run in Standard or 386 Enhanced modes. However, it was necessary to load Windows 3.0 in Real mode to run SWAPFILE.EXE, which allowed users to change virtual memory settings.

Standard mode was used most often as its requirements were more in-line with an average PC of that era – a 286 processor with at least 1 MB of memory. Incidentally, not all 286 and 386 computers remapped memory between 640 KB (the upper limit of Conventional memory) and 1 MB as extended memory — some did not show memory between 640 KB and 1 MB at all — so on some systems with 1 MB of RAM, there is no extended memory and memory was limited to 640 KB. On such a system, Windows was limited to real mode. Many 386 computers ran Windows 3.0 in Standard mode due to a lack of memory.

386 Enhanced mode implemented all the benefits of Standard mode, plus 32-bit addressing and paging for faster memory access, and virtual 8086 mode for safer execution of MS-DOS programs: each of them now ran in a virtual machine. In the previous modes, multiple MS-DOS programs could only be run in full-screen, and only the program currently active was executing; but in 386 enhanced mode, they could be run simultaneously in separate windows. This mode required a 386 processor and 1 MB of extended memory (in addition to the base 640KB) – beyond the specifications of most PCs sold in 1990.
[edit] Multimedia Extensions

The Multimedia Extensions were released in autumn 1991 to support sound cards, as well as CD-ROM drives, which were then becoming increasingly available. The Multimedia Extensions were released to Original Equipment Manufacturers (OEMs), mainly CD-ROM drive and sound card manufacturers, and added basic multimedia support for audio input and output and a CD audio player application to Windows 3.0. The Multimedia Extensions' new features were not available in Windows 3.0 real mode. Windows 3.1x would later incorporate many of its features. Microsoft developed the Windows Sound System sound card specification to complement these extensions.

The MME API was the first universal and standardized Windows audio API. Wave sound events played in Windows (up to Windows XP) and MIDI I/O use MME. The devices listed in the Multimedia/Sounds and Audio control panel applet represent the MME API of the sound card driver.

MME lacks channel mixing, so only one audio stream can be rendered at a time. MME supports sharing the audio device for playback between multiple applications starting with Windows 2000, up to two channels of recording, 16-bit audio bit depth and sampling rates of up to 44.1 kHz with all the audio being mixed and sampled to 44.1 kHz.

Windows 95 is a consumer-oriented graphical user interface-based operating system. It was released on August 24, 1995 by Microsoft,[2] and was a significant progression from the company's previous Windows products. During development it was referred to as Windows 4.0 or by the internal codename Chicago.

Windows 95 integrated Microsoft's formerly separate MS-DOS and Windows products. It featured significant improvements over its predecessor, Windows 3.1, most notably in the graphical user interface (GUI) and in its relatively simplified "plug-n-play" features. There were also major changes made at lower levels of the operating system, such as moving from a mainly 16-bit architecture to a pre-emptively multitasked 32-bit architecture.

In the marketplace, Windows 95 was a major success, and within a year or two of its release had become the most successful operating system ever produced. It also had the effect of driving other major players in the DOS-compatible operating system market out of business, something which would later be used in court against Microsoft. Some three years after its introduction, Windows 95 was succeeded by Windows 98.

* Windows 98 was the first operating system to use the Windows Driver Model (WDM). This fact was not well publicised when Windows 98 was released, and most hardware producers continued to develop drivers for the older VxD driver standard, which Windows 98 also supported. The WDM standard only achieved widespread adoption years later, mostly through Windows 2000 and Windows XP, as they are not compatible with the older VxD standard[4]. Windows Driver Model was introduced largely so that developers would write source compatible drivers for all future versions of Windows. Device driver access in WDM is actually implemented through a VxD device driver, NTKERN.VXD which implements several Windows NT-specific kernel support functions. NTKERN creates IRPs and sends them to WDM drivers.
* WDM Audio: Support for WDM audio enables digital mixing, routing and processing of simultaneous audio streams and kernel streaming with high quality sample rate conversion on Windows 98. WDM Audio allows for software emulation of legacy hardware to support MS-DOS games, DirectSound support and MIDI wavetable sythesis. A Microsoft GS Wavetable Synthesizer licensed from Roland shipped with Windows 98 for WDM audio drivers. Windows 98 supports digital playback of audio CDs. Windows 98 Second Edition improves WDM audio support by adding DirectSound hardware mixing and DirectSound 3D hardware abstraction, DirectMusic kernel support, KMixer sample-rate conversion (SRC) for capture streams and multichannel audio support. All audio is sampled by the Kernel Mixer to a fixed sampling rate which may result in some audio getting upsampled or downsampled and having a high latency, except when using Kernel Streaming or third party audio paths like ASIO which allow unmixed audio streams and lower latency.
* Windows 98, in general, provides improved—and a broader range of—support for IDE and SCSI drives and drive controllers, floppy drive controllers and all other classes of hardware than Windows 95.[5]
* Windows 98 had more robust USB support (e.g. support for USB composite devices) than Windows 95 which only had support in OEM versions (OSR2.1 or later).[6] Windows 98 supports USB hubs, USB scanners and imaging class devices. Windows 98 also introduces built-in support for some USB Human Interface Device class (USB HID) and PID class devices such as USB mice, keyboards, force feedback joysticks etc. including additional keyboard functions through a certain number of Consumer Page HID controls.[7] It includes a WDM streaming class driver to address real time multimedia data stream processing requirements and a WDM kernel-mode video transport for enhanced video playback and capture. USB audio device class support is present from Windows 98 SE onwards. Windows 98 Second Edition also introduced support for WDM for modems (and therefore USB modems and virtual COM ports). Microsoft driver support for both USB printers, and for USB mass-storage device class is not available for Windows 98; support for both was introduced in Windows 2000; however generic third party free drivers are available today for USB MSC devices.
* Basic FireWire (IEEE 1394) support
* Integrated Accelerated Graphics Port (AGP) support compared to the Windows 95 original release. (Note: USB Supplement to Windows 95 OSR2 and later releases of Windows 95 include AGP support).
* DVD support and UDF 1.02 read support
* ACPI 1.0 support which enabled Standby (ACPI S3) and Hibernate (ACPI S4) states. However, hibernation support was extremely limited, and vendor-specific. Hibernation was only available if compatible (PnP) hardware and BIOS are present, and the hardware manufacturer or OEM supplied compatible WDM drivers (non-VxD) drivers. There are also hibernation issues with the FAT32 file system[5], making hibernation problematic and unreliable.
* Still imaging architecture (STI) for scanners and cameras, Image Color Management 2.0 which supports more color spaces and TWAIN support
* Broadcast Driver Architecture
* Multiple monitor support allows using up to 8 multiple monitors and/or multiple graphics adapters on a single PC.
* Windows 98 shipped with DirectX 5.2 which notably included DirectShow. Windows 98 Second Edition shipped with DirectX 6.1.

[edit] Networking enhancements
Main article: Winsock

* TCP/IP: Windows 98 networking enhancements to TCP/IP include built-in support for Winsock 2, SMB signing,[8] a new IP Helper API, Automatic Private IP Addressing (APIPA) (also known as link-local addressing), IP multicasting (including IGMPv2 support and ICMP Router Discovery - RFC 1256), and performance enhancements for high-speed high bandwidth networks (TCP large windows and time stamps - RFC 1323, Selective Acknowledgement (SACK) - RFC 2018, TCP Fast Retransmit and Fast Recovery). Multihoming support with TCP/IP is improved and includes RIP listener support.
* The DHCP client has been enhanced to include address assignment conflict detection and longer timeout intervals. NetBT configuration in the WINS client has been improved to continue persistently querying multiple WINS servers if it failed to establish the initial session until all of the WINS servers specified have been queried or a connection is established.
* NDIS 5.0 support means Windows 98 can support a wide range of network media, including Ethernet, Fiber Distributed Data Interface (FDDI), token ring, Asynchronous Transfer Mode (ATM), wide area networks (WANs), ISDN, X.25, and Frame Relay. Additional features include NDIS power management, support for QoS, WMI and support for a single INF file format across all Windows versions.
* Dial-Up Networking: Windows 98 Dial-Up Networking supports PPTP tunneling, support for ISDN adapters, multilink support, and connection-time scripting to automate non-standard login connections. Multilink channel aggregation enables users to combine all available dial-up lines to achieve higher transfer speeds. PPP connection logs can show actual packets being passed and Windows 98 allows PPP logging per connection. The Dial-Up Networking improvements are also available in Windows 95 OSR2 and downloadable for earlier Windows 95 releases.
* For networked computers that have user profiles enabled, Windows 98 introduces Microsoft Family Logon which lists all users that have been configured for that computer, enabling users to simply select their names from a list rather than having to type it in. The same feature can be added to Windows 95 if Internet Explorer 4.0 is installed.
* Windows 98 has built-in support for browsing DFS trees on SMB shares.
* IrDA support: Windows 98 supports IrDA 3.0 that specifies both Serial Infrared Devices (SIR) and Fast Infrared (FIR) devices, which are capable of sending and receiving data at 4 Mbit/s. Infrared Recipient, a new application for transferring files through an infrared connection is included. The IrDA stack in Windows 98 supports networking profiles over the IrCOMM kernel-mode driver.
* Windows 98 Second Edition added Internet Connection Sharing (IP forwarding and NAT capabilities). Windows Me later supported NAT traversal by means of UPnP. UPnP and NAT traversal APIs can also be installed on Windows 98 by installing the Windows XP Network Setup Wizard.[9]
* L2TP/IPsec VPN support as a downloadable client.
* Ability to take advantage of several Windows 2000 Active Directory features by installing Active Directory Client Extensions.

[edit] Improvements to the system and tools

* Microsoft Backup supports differential backup and SCSI tape devices in Windows 98.
* Disk Cleanup - This tool enables users to clear their disks of unnecessary files. Cleanup locations are extensible through Disk Cleanup handlers. Disk Cleanup can be automated for regular silent cleanups.
* Disk Defragmenter - Disk Defragmenter has been improved to rearrange program files that are frequently used to a hard disk region optimized for program start.[10]
* Scanreg (DOS) and ScanRegW — Registry Checker tool used to backup, restore or optimize the Windows registry. It tests the registry's integrity and saves a backup copy each time Windows successfully boots. The maximum amount of copies could be customized by the user through "scanreg.ini" file. The restoration of a registry that causes Windows to fail to boot can only be done from DOS mode.
* Msconfig — A system utility used to disable programs and services that are not required to run the computer.
* Maintenance Wizard - Tool that schedules and automates ScanDisk, Disk Defragmenter and Disk Cleanup.
* System File Checker - Tool to check installed versions of system files to ensure they were the same version as the one installed with Windows 98 or newer. Corrupt or older versions are replaced by the correct versions. This tool was introduced to resolve the DLL hell issue and was replaced in Windows Me by System File Protection.
* Fast Shutdown feature that initiates shutdown without uninitializing device drivers.[11]
* Write-behind caching for removable disk drives.
* FAT32 converter utility for converting FAT16 drives to FAT32 without formatting the partition.
* The Windows 98 Startup Disk contains generic, real-mode ATAPI and SCSI CD-ROM drivers and has been preconfigured to automatically start MS-DOS mode with CD-ROM support enabled. For computers without an operating system and that do not support booting from optical drives, the Startup disk can be used to boot into MS-DOS and automatically start Windows 98 setup from the CD.
* Dr. Watson: Windows 98 includes an improved version of the Dr. Watson utility that collects and lists comprehensive information such as running tasks, startup programs with their command line switches, system patches, kernel driver, user drivers, DOS drivers and 16-bit modules. With Dr. Watson loaded in the system tray, whenever a software fault occurs (general protection fault, hang, etc.), Dr. Watson will intercept it and indicate what software crashed and its cause. All of the collected information is logged to the \Windows\DrWatson folder.
* WinAlign: WinAlign (Walign.exe and Winalign.exe) is a tool designed to optimize the performance of executable code (binaries). It aligns binary sections along 4 KB boundaries, aligning the executable sections with the memory pages. This allows the Windows 98 MapCache feature to map directly to sections in cache, resulting in a significant increase in performance through more available memory.[12] Walign.exe is included in Windows 98 for optimizing Microsoft Office programs. Winalign.exe is included in the Windows 98 Resource Kit to optimize other programs.
* Windows Report Tool: Windows Report Tool takes a snapshot of system configuration and lets users submit a manual problem report along with system information to technicians. It has e-mail confirmation for submitted reports.

A Critical Update Notification in Windows 98
[edit] Miscellaneous improvements

* Title bars of windows and dialog boxes support two-color gradients. Windows 98 menus and tooltips support slide animation.
* Windows Explorer in Windows 98, like Windows 95, converts all uppercase filenames to Sentence case for readability purposes,[13] however, it also provides an option Allow all uppercase names to display them in their original case.
* Microsoft Magnifier, Accessibility Wizard and Microsoft Active Accessibility 1.1 API upgradeable to MSAA 2.0.
* The system could be updated using Windows Update. A utility to automatically notify of critical updates was later released.
* HTML Help and 15 Troubleshooting Wizards
* Windows Script Host upgradeable to version 5.6
* Telephony API (TAPI) 2.1
* DCOM version 1.2
* WebTV for Windows which allows viewing television on the computer if a compatible TV Tuner is installed. TV listings could updated from the Internet and WaveTop Data Broadcasting allowed extra data about broadcasts to be received via regular television signals using an antenna or cable, by embedding data streams into the vertical blanking interval (VBI) portion of existing broadcast television signals.
* Windows 98 integrates shell enhancements, themes and other features from Microsoft Plus! for Windows 95 such as DriveSpace 3, Compression Agent, Dial-Up Networking Server, Dial-Up Scripting Tool and Task Scheduler. 3D Pinball is included on the CD-ROM but not installed by default. Windows 98 had its own separately purchasable Plus! pack called Plus! 98.
* Ability to list fonts by similarity determined using PANOSE information.
* Improved accessories: Users can configure the font in Notepad. Microsoft Paint supports GIF transparency. HyperTerminal supports a TCP/IP connection method allowing it to be used as a Telnet client. Imaging for Windows is updated. System Monitor supports logging.
* Support for compressed CAB files
* Tools to automate setup such as Batch 98 and INFInst.exe support error-checking, gathering information automatically to create an INF file directly from the registry of the machine, customizing IE4, shell and desktop settings and adding custom drivers.
* Several other Resource Kit tools are included on the Windows 98 CD.[14]
* Besides Internet Explorer, many other internet tools were included such as Outlook Express, Windows Address Book, FrontPage Express, Microsoft Chat, Personal Web Server and a Web Publishing Wizard, NetMeeting and NetShow Player (in the original release of Windows 98) which was replaced by Windows Media Player 6.2 in Windows 98 Second Edition.
* Windows 98 has new system event sounds for low battery alarm and critical battery alarm. The Windows 98 startup sound was composed by Ken Kato.
* Windows 98 shipped with Flash Player and Shockwave Player preinstalled.[15]

[edit] Editions
Windows 98 Upgrade cover.
[edit] Windows 98 Second Edition

Windows 98 Second Edition (often shortened to SE) is an updated release of Windows 98, released on 5 May 1999. It includes fixes for many minor issues, improved WDM audio and modem support, improved USB support and FireWire DV camcorder support, the replacement of Internet Explorer 4.0 with Internet Explorer 5.0 and related shell updates. Also included is Wake-On-LAN support (if ACPI compatible NDIS drivers are present) and Internet Connection Sharing, which allows multiple computers on a LAN to share a single Internet connection through Network Address Translation. Other features in the update include DirectX 6.1 which introduced DirectMusic, improvements to Asynchronous Transfer Mode support (IP/ATM, PPP/ATM and WinSock 2/ATM support), Windows Media Player 6.2 replacing the older Media Player, Microsoft NetMeeting 3.0, MDAC 2.1 and WMI. A memory overflow issue was resolved which in the older version of Windows 98 would crash most systems if left running for 49.7 days (equal to 2³² milliseconds)[16]. Windows 98 SE could be obtained as retail upgrade and full version packages, as well as OEM and a Second Edition Updates Disc for existing Windows 98 users. Windows 98 Second Edition did not ship with the WinG API or RealPlayer 4.0 unlike the original release of Windows 98, both of these being superseded by DirectX and Windows Media Player.