The Data General/One ( DG-1 ) was a laptop introduced in 1984 by Data General .
115-443: The nine-pound battery-powered 1984 Data General/One ran MS-DOS and had dual 3.5" diskettes, a 79-key full-stroke keyboard, 128 KB to 512 KB of RAM, and a monochrome LCD screen capable of either the standard 80×25 characters or full CGA graphics (640×200). It was a laptop comparable in capabilities to desktops of the era. The Data General/One offered several features in comparison with contemporary portable computers. For instance,
230-458: A relocatable format using the filename extension .CMD to avoid name conflicts with CP/M-80 and MS-DOS .COM files. MS-DOS version 1.0 added a more advanced relocatable . EXE executable file format. Most of the machines in the early days of MS-DOS had differing system architectures and there was a certain degree of incompatibility, and subsequently vendor lock-in . Users who began using MS-DOS with their machines were compelled to continue using
345-428: A system call to perform a block I/O write operation, then the system call might execute the following instructions: While the writing takes place, the operating system will context switch to other processes as normal. When the device finishes writing, the device will interrupt the currently running process by asserting an interrupt request . The device will also place an integer onto the data bus. Upon accepting
460-618: A 1994 settlement agreement limiting Microsoft to per-copy licensing. Digital Research did not gain by this settlement, and years later its successor in interest, Caldera , sued Microsoft for damages in the Caldera v. Microsoft lawsuit. It was believed that the settlement ran in the order of $ 150 million , but was revealed in November 2009 with the release of the Settlement Agreement to be $ 280 million . Microsoft also used
575-448: A DOS startup disk on Windows Vista , the files on the startup disk are dated April 18, 2005, but are otherwise unchanged, including the string "MS-DOS Version 8 Copyright 1981–1999 Microsoft Corp" inside COMMAND.COM . Windows 7, 8, and 8.1 can also create a MS-DOS startup disk. Starting with Windows 10 , the ability to create a MS-DOS startup disk has been removed, and so either a virtual machine running MS-DOS or an older version (in
690-516: A Graphical User Interface (GUI) on top of MS-DOS. With Windows 95 , 98 , and Me , the role of MS-DOS was reduced to a boot loader according to Microsoft, with MS-DOS programs running in a virtual DOS machine within 32-bit Windows, with ability to boot directly into MS-DOS retained as a backward compatibility option for applications that required real mode access to the hardware, which was generally not possible within Windows. The command line accessed
805-645: A computer even if they are not compatible with the base operating system. A library operating system (libOS) is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with a single application and configuration code to construct a unikernel : a specialized (only the absolute necessary pieces of code are extracted from libraries and bound together ), single address space , machine image that can be deployed to cloud or embedded environments. The operating system code and application code are not executed in separated protection domains (there
920-755: A copy of the Windows Me boot disk, stripped down to bootstrap only. This is accessible only by formatting a floppy as an "MS-DOS startup disk". Files like the driver for the CD-ROM support were deleted from the Windows Me bootdisk and the startup files ( AUTOEXEC.BAT and CONFIG.SYS ) no longer had content. This modified disk was the base for creating the MS-DOS image for Windows XP. Some of the deleted files can be recovered with an undelete tool. When booting up an MS-DOS startup disk made with Windows XP's format tool,
1035-585: A development of MULTICS for a single user. Because UNIX's source code was available, it became the basis of other, incompatible operating systems, of which the most successful were AT&T 's System V and the University of California 's Berkeley Software Distribution (BSD). To increase compatibility, the IEEE released the POSIX standard for operating system application programming interfaces (APIs), which
1150-541: A forceful letter to PC Week (November 5, 1990), denying that Microsoft was engaged in FUD tactics ("to serve our customers better, we decided to be more forthcoming about version 5.0") and denying that Microsoft copied features from DR DOS: "The feature enhancements of MS-DOS version 5.0 were decided and development was begun long before we heard about DR DOS 5.0. There will be some similar features. With 50 million MS-DOS users, it shouldn't be surprising that DRI has heard some of
1265-448: A higher price. Executable programs for CP/M-86 and MS-DOS were not interchangeable with each other; many applications were sold in both MS-DOS and CP/M-86 versions until MS-DOS became preponderant (later Digital Research operating systems could run both MS-DOS and CP/M-86 software). MS-DOS originally supported the simple .COM , which was modeled after a similar but binary-incompatible format known from CP/M-80 . CP/M-86 instead supported
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#17327868629281380-484: A large legal settlement was paid. In the twenty-first century, Windows continues to be popular on personal computers but has less market share of servers. UNIX operating systems, especially Linux, are the most popular on enterprise systems and servers but are also used on mobile devices and many other computer systems. On mobile devices, Symbian OS was dominant at first, being usurped by BlackBerry OS (introduced 2002) and iOS for iPhones (from 2007). Later on,
1495-458: A large share of the business computer market. Microsoft and IBM together began what was intended as the follow-on to MS-DOS/PC DOS, called OS/2 . When OS/2 was released in 1987, Microsoft began an advertising campaign announcing that "DOS is Dead" and stating that version 4 was the last full release. OS/2 was designed for efficient multi-tasking and offered a number of advanced features that had been designed together with similar look and feel ; it
1610-442: A library with no protection between applications, such as eCos . A hypervisor is an operating system that runs a virtual machine . The virtual machine is unaware that it is an application and operates as if it had its own hardware. Virtual machines can be paused, saved, and resumed, making them useful for operating systems research, development, and debugging. They also enhance portability by enabling applications to be run on
1725-447: A malformed machine instruction . However, the most common error conditions are division by zero and accessing an invalid memory address . Users can send messages to the kernel to modify the behavior of a currently running process. For example, in the command-line environment , pressing the interrupt character (usually Control-C ) might terminate the currently running process. To generate software interrupts for x86 CPUs,
1840-455: A particular application's memory is stored, or even whether or not it has been allocated yet. In modern operating systems, memory which is accessed less frequently can be temporarily stored on a disk or other media to make that space available for use by other programs. This is called swapping , as an area of memory can be used by multiple programs, and what that memory area contains can be swapped or exchanged on demand. Virtual memory provides
1955-407: A particular model), or per-copy (a fee for each copy of MS-DOS installed). The largest manufacturers used the per-processor arrangement, which had the lowest fee. This arrangement made it expensive for the large manufacturers to migrate to any other operating system, such as DR DOS. In 1991, the U.S. government Federal Trade Commission began investigating Microsoft's licensing procedures, resulting in
2070-503: A program does not interfere with memory already in use by another program. Since programs time share, each program must have independent access to memory. Cooperative memory management, used by many early operating systems, assumes that all programs make voluntary use of the kernel 's memory manager, and do not exceed their allocated memory. This system of memory management is almost never seen any more, since programs often contain bugs which can cause them to exceed their allocated memory. If
2185-408: A program fails, it may cause memory used by one or more other programs to be affected or overwritten. Malicious programs or viruses may purposefully alter another program's memory, or may affect the operation of the operating system itself. With cooperative memory management, it takes only one misbehaved program to crash the system. Memory protection enables the kernel to limit a process' access to
2300-440: A program tries to access memory that is not accessible memory, but nonetheless has been allocated to it, the kernel is interrupted (see § Memory management ) . This kind of interrupt is typically a page fault . When the kernel detects a page fault it generally adjusts the virtual memory range of the program which triggered it, granting it access to the memory requested. This gives the kernel discretionary power over where
2415-470: A significant amount of CPU time. Direct memory access (DMA) is an architecture feature to allow devices to bypass the CPU and access main memory directly. (Separate from the architecture, a device may perform direct memory access to and from main memory either directly or via a bus.) When a computer user types a key on the keyboard, typically the character appears immediately on the screen. Likewise, when
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#17327868629282530-402: A specific moment in time. Hard real-time systems require exact timing and are common in manufacturing , avionics , military, and other similar uses. With soft real-time systems, the occasional missed event is acceptable; this category often includes audio or multimedia systems, as well as smartphones. In order for hard real-time systems be sufficiently exact in their timing, often they are just
2645-513: A standard Microsoft kernel, which they would typically supply on disk to end users along with the hardware. Thus, there were many different versions of "MS-DOS" for different hardware, and there is a major distinction between an IBM-compatible (or ISA) machine and an MS-DOS [compatible] machine. Some machines, like the Tandy 2000 , were MS-DOS compatible but not IBM-compatible, so they could run software written exclusively for MS-DOS without dependence on
2760-417: A user moves a mouse , the cursor immediately moves across the screen. Each keystroke and mouse movement generates an interrupt called Interrupt-driven I/O . An interrupt-driven I/O occurs when a process causes an interrupt for every character or word transmitted. Devices such as hard disk drives , solid-state drives , and magnetic tape drives can transfer data at a rate high enough that interrupting
2875-453: A variation of the classic reader/writer problem . The writer receives a pipe from the shell for its output to be sent to the reader's input stream. The command-line syntax is alpha | bravo . alpha will write to the pipe when its computation is ready and then sleep in the wait queue. bravo will then be moved to the ready queue and soon will read from its input stream. The kernel will generate software interrupts to coordinate
2990-602: A variety of other computers based on various other processors were in serious competition with the IBM PC: the Apple II , Mac , Commodore 64 and others did not use the 808x processor; many 808x machines of different architectures used custom versions of MS-DOS. At first all these machines were in competition. In time the IBM PC hardware configuration became dominant in the 808x market as software written to communicate directly with
3105-450: A variety of tactics in MS-DOS and several of their applications and development tools that, while operating perfectly when running on genuine MS-DOS (and PC DOS), would break when run on another vendor's implementation of DOS. Notable examples of this practice included: All versions of Microsoft Windows have had an MS-DOS or MS-DOS-like command-line interface called MS-DOS Prompt which redirected input to MS-DOS and output from MS-DOS to
3220-456: A virtual machine or dual boot) must be used to format a floppy disk, or an image must be obtained from an external source. Other solutions include using DOS compatible alternatives, such as FreeDOS or even copying the required files and boot sector themselves. The last remaining components related to MS-DOS was the NTVDM component, which was removed entirely in Windows starting with Windows 11 as
3335-418: Is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers . In the personal computer market, as of September 2024 , Microsoft Windows holds a dominant market share of around 73%. macOS by Apple Inc. is in second place (15%), Linux is in third place (5%), and ChromeOS
3450-617: Is on' is no joke. It happened in our offices." An updated version of the DG-1 appeared later with a much improved electroluminescent screen. However, the light-producing display could be washed out by bright sunlight. Additionally, the new screen was power hungry and consumed so much power that the battery option was removed, thereby causing the DG-1 to lose its status as a true portable. MS-DOS MS-DOS ( / ˌ ɛ m ˌ ɛ s ˈ d ɒ s / em-es- DOSS ; acronym for Microsoft Disk Operating System , also known as Microsoft DOS )
3565-562: Is remote direct memory access , which enables each CPU to access memory belonging to other CPUs. Multicomputer operating systems often support remote procedure calls where a CPU can call a procedure on another CPU, or distributed shared memory , in which the operating system uses virtualization to generate shared memory that does not physically exist. A distributed system is a group of distinct, networked computers—each of which might have their own operating system and file system. Unlike multicomputers, they may be dispersed anywhere in
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3680-484: Is a change away from the currently running process. Similarly, both hardware and software interrupts execute an interrupt service routine . Software interrupts may be normally occurring events. It is expected that a time slice will occur, so the kernel will have to perform a context switch . A computer program may set a timer to go off after a few seconds in case too much data causes an algorithm to take too long. Software interrupts may be error conditions, such as
3795-422: Is an operating system for x86 -based personal computers mostly developed by Microsoft . Collectively, MS-DOS, its rebranding as IBM PC DOS , and a few operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS" (which is also the generic acronym for disk operating system ). MS-DOS was the main operating system for IBM PC compatibles during the 1980s, from which point it
3910-422: Is difficult to define, but has been called "the layer of software that manages a computer's resources for its users and their applications ". Operating systems include the software that is always running, called a kernel —but can include other software as well. The two other types of programs that can run on a computer are system programs —which are associated with the operating system, but may not be part of
4025-896: Is in fourth place (2%). In the mobile sector (including smartphones and tablets ), as of September 2023 , Android's share is 68.92%, followed by Apple's iOS and iPadOS with 30.42%, and other operating systems with .66%. Linux distributions are dominant in the server and supercomputing sectors. Other specialized classes of operating systems (special-purpose operating systems), such as embedded and real-time systems, exist for many applications. Security-focused operating systems also exist. Some operating systems have low system requirements (e.g. light-weight Linux distribution ). Others may have higher system requirements. Some operating systems require installation or may come pre-installed with purchased computers ( OEM -installation), whereas others may run directly from media (i.e. live CD ) or flash memory (i.e. USB stick). An operating system
4140-412: Is mainly for education and experimentation with historic operating systems and for new programmers to gain an understanding of how low-level software works, both historic and current. According to program manager Rich Turner, the other versions could not be open-sourced due to third-party licensing restrictions. Due to the historical nature of the software, Microsoft will not accept any pull requests to
4255-518: Is often called the MS-DOS Prompt. In part, this was the official name for it in Windows 9x and early versions of Windows NT (NT 3.5 and earlier), and in part because the SoftPC emulation of DOS redirects output into it. Actually only COMMAND.COM and other 16-bit commands run in an NTVDM with AUTOEXEC.NT and CONFIG.NT initialization determined by _DEFAULT.PIF , optionally permitting
4370-443: Is only a single application running, at least conceptually, so there is no need to prevent interference between applications) and OS services are accessed via simple library calls (potentially inlining them based on compiler thresholds), without the usual overhead of context switches , in a way similarly to embedded and real-time OSes. Note that this overhead is not negligible: to the direct cost of mode switching it's necessary to add
4485-441: Is still used in embedded x86 systems due to its simple architecture and minimal memory and processor requirements, though some current products have switched to the still-maintained open-source alternative FreeDOS . In 2018, Microsoft released the source code for MS-DOS 1.25 and 2.0 on GitHub , with the source code for MS-DOS 4.00 being released in the same repository six years later. The purpose of this, according to Microsoft,
4600-499: Is supported by most UNIX systems. MINIX was a stripped-down version of UNIX, developed in 1987 for educational uses, that inspired the commercially available, free software Linux . Since 2008, MINIX is used in controllers of most Intel microchips , while Linux is widespread in data centers and Android smartphones. The invention of large scale integration enabled the production of personal computers (initially called microcomputers ) from around 1980. For around five years,
4715-473: Is that they do not load user-installed software. Consequently, they do not need protection between different applications, enabling simpler designs. Very small operating systems might run in less than 10 kilobytes , and the smallest are for smart cards . Examples include Embedded Linux , QNX , VxWorks , and the extra-small systems RIOT and TinyOS . A real-time operating system is an operating system that guarantees to process events or data by or at
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4830-435: Is the part of the operating system that provides protection between different applications and users. This protection is key to improving reliability by keeping errors isolated to one program, as well as security by limiting the power of malicious software and protecting private data, and ensuring that one program cannot monopolize the computer's resources. Most operating systems have two modes of operation: in user mode ,
4945-537: The ADM-3A or Data General's own Dasher terminals (the cost of the laptop would not have seemed excessive in such situations). The screen was this computer's other great flaw. Although unusually large, the LCD display had very low contrast and narrow viewing angle . InfoWorld stated that "the godawful screen made a better mirror than display", and PC Magazine reported that "The exchange 'Why don't you turn it on?' / 'It
5060-542: The CP/M (Control Program for Microcomputers) was the most popular operating system for microcomputers. Later, IBM bought the DOS (Disk Operating System) from Microsoft . After modifications requested by IBM, the resulting system was called MS-DOS (MicroSoft Disk Operating System) and was widely used on IBM microcomputers. Later versions increased their sophistication, in part by borrowing features from UNIX. Apple 's Macintosh
5175-504: The INT assembly language instruction is available. The syntax is INT X , where X is the offset number (in hexadecimal format) to the interrupt vector table . To generate software interrupts in Unix-like operating systems, the kill(pid,signum) system call will send a signal to another process. pid is the process identifier of the receiving process. signum is
5290-591: The Intel 8086 and 8088 processors, including the IBM PC and clones, the initial competition to the PC DOS/MS-DOS line came from Digital Research , whose CP/M operating system had inspired MS-DOS. In fact, there remains controversy as to whether QDOS was more or less plagiarized from early versions of CP/M code. Digital Research released CP/M-86 a few months after MS-DOS, and it was offered as an alternative to MS-DOS and Microsoft's licensing requirements, but at
5405-581: The Santa Cruz Operation (SCO). On March 25, 2014, Microsoft made the code to SCP MS-DOS 1.25 and a mixture of Altos MS-DOS 2.11 and TeleVideo PC DOS 2.11 available to the public under the Microsoft Research License Agreement , which makes the code source-available , but not open source as defined by Open Source Initiative or Free Software Foundation standards. Microsoft would later re-license
5520-739: The Windows NT -derived 32-bit operating systems ( Windows NT , 2000 , XP and newer), developed alongside the 9x series, do not contain MS-DOS compatibility as a core component of the operating system nor do they rely on it for bootstrapping, as NT was not with the level of support for legacy MS-DOS and Win16 apps that Windows 9x was, but does provide limited DOS emulation called NTVDM (NT Virtual DOS Machine) to run DOS applications and provide DOS-like command prompt windows. 64-bit versions of Windows NT prior to Windows 11 (and Windows Server 2008 R2 by extension) do not provide DOS emulation and cannot run DOS applications natively. Windows XP contains
5635-420: The transistor in the mid-1950s, mainframes began to be built. These still needed professional operators who manually do what a modern operating system would do, such as scheduling programs to run, but mainframes still had rudimentary operating systems such as Fortran Monitor System (FMS) and IBSYS . In the 1960s, IBM introduced the first series of intercompatible computers ( System/360 ). All of them ran
5750-748: The "pre-announcement" of MS-DOS 6.0 again stifled the sales of DR DOS. Microsoft had been accused of carefully orchestrating leaks about future versions of MS-DOS in an attempt to create what in the industry is called FUD ( fear, uncertainty, and doubt ) regarding DR DOS. For example, in October 1990, shortly after the release of DR DOS 5.0, and long before the eventual June 1991 release of MS-DOS 5.0, stories on feature enhancements in MS-DOS started to appear in InfoWorld and PC Week . Brad Silverberg , then Vice President of Systems Software at Microsoft and general manager of its Windows and MS-DOS Business Unit, wrote
5865-451: The 1994 release of MS-DOS 6.21, which had disk compression removed. Shortly afterwards came version 6.22, with a new version of the disk compression system, DriveSpace, which had a different compression algorithm to avoid the infringing code. Prior to 1995, Microsoft licensed MS-DOS (and Windows) to computer manufacturers under three types of agreement: per-processor (a fee for each system the company sold), per-system (a fee for each system of
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#17327868629285980-527: The CMOS (low battery consumption) serial I-O chip available at design time, a CMOS version of the Intel 8251 , was register incompatible with the 8250 serial IC standard for the IBM PC. As a result, software written for the PC serial ports would not run correctly. This required the use of software written using the relatively slower and less flexible BIOS interrupt call (014h), or software written exclusively for
6095-410: The CPU for every byte or word transferred, and having the CPU transfer the byte or word between the device and memory, would require too much CPU time. Data is, instead, transferred between the device and memory independently of the CPU by hardware such as a channel or a direct memory access controller; an interrupt is delivered only when all the data is transferred. If a computer program executes
6210-474: The CPU to re-enter supervisor mode , placing the kernel in charge. This is called a segmentation violation or Seg-V for short, and since it is both difficult to assign a meaningful result to such an operation, and because it is usually a sign of a misbehaving program, the kernel generally resorts to terminating the offending program, and reports the error. Windows versions 3.1 through ME had some level of memory protection, but programs could easily circumvent
6325-401: The DG-1. Video memory came out of that available for the operating system; for example, if 256 KB of RAM was installed, only 204 KB might be available to the operating system and user's programs. Although Creative Computing termed the price of US$ 2895 "competitive," it was a very expensive system, and usually-needed additions such as more RAM and an external 5 1 ⁄ 4 " drive drove
6440-561: The DOS command line (usually COMMAND.COM ) through a Windows module (WINOLDAP.MOD). Windows NT-based operating systems boot to a kernel whose purpose is to load Windows and run the system. One cannot run Win32 applications in the loader system in the manner that OS/2, UNIX or consumer versions of Windows can launch character-mode sessions. The command session permits running various supported command-line utilities from Win32, MS-DOS, OS/2 1.x and POSIX. The emulators for MS-DOS, OS/2 and POSIX use
6555-524: The IBM 5150 or the IBM PC . Within a year, Microsoft licensed MS-DOS to over 70 other companies. It was designed to be an OS that could run on any 8086-family computer. Each computer would have its own distinct hardware and its own version of MS-DOS, similar to the situation that existed for CP/M , and with MS-DOS emulating the same solution as CP/M to adapt for different hardware platforms. To this end, MS-DOS
6670-470: The MS-DOS Prompt, or, in later versions, Command Prompt . This could run many DOS and variously Win32, OS/2 1.x and POSIX command-line utilities in the same command-line session, allowing piping between commands. The user interface, and the icon up to Windows 2000, followed the native MS-DOS interface. The Command Prompt introduced with Windows NT is not actually MS-DOS, but shares some commands with MS-DOS. The 16-bit versions of Windows (up to 3.11) ran as
6785-434: The MS-DOS name for all versions but the IBM one, which was originally called "IBM Personal Computer DOS", later shortened to IBM PC DOS . (Competitors released compatible DOS systems such as DR-DOS and PTS-DOS that could also run MS-DOS applications.) In the former Eastern bloc , MS-DOS derivatives named DCP ( Disk Control Program [ de ] ) 3.20 and 3.30 (DCP 1700, DCP 3.3) and WDOS existed in
6900-405: The NTVDM and can therefore no longer natively run DOS or 16-bit Windows applications. There are alternatives such as virtual machine emulators such as Microsoft's own Virtual PC , as well as VMware , DOSBox etc., unofficial compatibility layers such as NTVDMx64, OTVDM (WineVDM), Win3mu and others. The introduction of Windows 3.0 in 1990, with an easy-to-use graphical user interface , marked
7015-549: The PC hardware without using standard operating system calls ran much faster, but on true PC-compatibles only. Non-PC-compatible 808x machines were too small a market to have fast software written for them alone, and the market remained open only for IBM PCs and machines that closely imitated their architecture, all running either a single version of MS-DOS compatible only with PCs, or the equivalent IBM PC DOS. Most clones cost much less than IBM-branded machines of similar performance, and became widely used by home users, while IBM PCs had
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#17327868629287130-520: The Windows GUI; this capability was retained through Windows 98 Second Edition. Windows Me removed the capability to boot its underlying MS-DOS 8.0 alone from a hard disk, but retained the ability to make a DOS boot floppy disk (called an "Emergency Boot Disk") and can be hacked to restore full access to the underlying DOS. On December 31, 2001, Microsoft declared all versions of MS-DOS 6.22 and older obsolete and stopped providing support and updates for
7245-538: The application program, which then interacts with the user and with hardware devices. However, in some systems an application can request that the operating system execute another application within the same process, either as a subroutine or in a separate thread, e.g., the LINK and ATTACH facilities of OS/360 and successors . An interrupt (also known as an abort , exception , fault , signal , or trap ) provides an efficient way for most operating systems to react to
7360-424: The background for loading Windows 9x . MS-DOS was a renamed form of 86-DOS – owned by Seattle Computer Products , written by Tim Paterson . Development of 86-DOS took only six weeks, as it was basically a clone of Digital Research 's CP/M (for 8080/Z80 processors), ported to run on 8086 processors and with two notable differences compared to CP/M: an improved disk sector buffering logic, and
7475-496: The beginning of the end for the command-line driven MS-DOS. With the release of Windows 95 (and continuing in the Windows 9x product line through to Windows Me ), an integrated version of MS-DOS was used for bootstrapping , troubleshooting, and backwards-compatibility with old DOS software, particularly games, and no longer released as a standalone product. In Windows 95, the DOS, called MS-DOS 7, can be booted separately, without
7590-666: The code under the MIT License on September 28, 2018, making these versions free software . Microsoft later released the code for MS-DOS 4.00 on April 25, 2024, under the same license. As an April Fool's Day joke in 2015, Microsoft Mobile launched a Windows Phone application called MS-DOS Mobile which was presented as a new mobile operating system and worked similar to MS-DOS. Microsoft licensed or released versions of MS-DOS under different names like Lifeboat Associates "Software Bus 86" a.k.a. SB-DOS , COMPAQ-DOS , NCR-DOS or Z-DOS before it eventually enforced
7705-455: The code. Users, however, are allowed and fully encouraged to fork the repository containing the MS-DOS source code and make their own modifications, and do whatever they like with it. Operating system An operating system ( OS ) is system software that manages computer hardware and software resources, and provides common services for computer programs . Time-sharing operating systems schedule tasks for efficient use of
7820-453: The computer's memory. Various methods of memory protection exist, including memory segmentation and paging . All methods require some level of hardware support (such as the 80286 MMU), which does not exist in all computers. In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should allow a running program to access. Attempts to access other addresses trigger an interrupt, which causes
7935-471: The details of how interrupt service routines behave vary from operating system to operating system. However, several interrupt functions are common. The architecture and operating system must: A software interrupt is a message to a process that an event has occurred. This contrasts with a hardware interrupt — which is a message to the central processing unit (CPU) that an event has occurred. Software interrupts are similar to hardware interrupts — there
8050-422: The environment. Interrupts cause the central processing unit (CPU) to have a control flow change away from the currently running program to an interrupt handler , also known as an interrupt service routine (ISR). An interrupt service routine may cause the central processing unit (CPU) to have a context switch . The details of how a computer processes an interrupt vary from architecture to architecture, and
8165-410: The hardware checks that the software is only executing legal instructions, whereas the kernel has unrestricted powers and is not subject to these checks. The kernel also manages memory for other processes and controls access to input/output devices. The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with
8280-493: The hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and execution of application programs. Executing an application program typically involves the creation of a process by the operating system kernel , which assigns memory space and other resources, establishes a priority for the process in multi-tasking systems, loads program binary code into memory, and initiates execution of
8395-511: The host's window in the same way that Win16 applications use the Win32 explorer. Using the host's window allows one to pipe output between emulations. The MS-DOS emulation takes place through the NTVDM (NT Virtual DOS Machine). This is a modified SoftPC (a former product similar to VirtualPC ), running a modified MS-DOS 5 (NTIO.SYS and NTDOS.SYS). The output is handled by the console DLLs, so that
8510-418: The indirect pollution of important processor structures (like CPU caches , the instruction pipeline , and so on) which affects both user-mode and kernel-mode performance. The first computers in the late 1940s and 1950s were directly programmed either with plugboards or with machine code inputted on media such as punch cards , without programming languages or operating systems. After the introduction of
8625-404: The interrupt request, the operating system will: When the writing process has its time slice expired, the operating system will: With the program counter now reset, the interrupted process will resume its time slice. Among other things, a multiprogramming operating system kernel must be responsible for managing all system memory which is currently in use by the programs. This ensures that
8740-701: The introduction of FAT12 instead of the CP/M filesystem . This first version was shipped in August 1980. Microsoft, which needed an operating system for the IBM Personal Computer , hired Tim Paterson in May 1981 and bought 86-DOS 1.10 for US$ 25,000 in July of the same year. Microsoft kept the version number, but renamed it MS-DOS. They also licensed MS-DOS 1.10/1.14 to IBM, which, in August 1981, offered it as PC DOS 1.0 as one of three operating systems for
8855-431: The kernel—and applications—all other software. There are three main purposes that an operating system fulfills: With multiprocessors multiple CPUs share memory. A multicomputer or cluster computer has multiple CPUs, each of which has its own memory . Multicomputers were developed because large multiprocessors are difficult to engineer and prohibitively expensive; they are universal in cloud computing because of
8970-699: The late 1980s. They were produced by the East German electronics manufacturer VEB Robotron . The following versions of MS-DOS were released to the public: Support for IBM's XT 10 MB hard disk drives, support up to 16 MB or 32 MB FAT12 -formatted hard disk drives depending on the formatting tool shipped by OEMs, user-installable device drivers, tree-structure filing system, Unix-like inheritable redirectable file handles, non-multitasking child processes an improved Terminate and Stay Resident (TSR) API, environment variables, device driver support, FOR and GOTO loops in batch files, ANSI.SYS . Microsoft DOS
9085-402: The limits of their contemporary hardware. Very soon an IBM-compatible architecture became the goal, and before long all 8086-family computers closely emulated IBM's hardware , and only a single version of MS-DOS for a fixed hardware platform was needed for the market. This version is the version of MS-DOS that is discussed here, as the dozens of other OEM versions of "MS-DOS" were only relevant to
9200-400: The memory allocated to a different one. Around the same time, teleprinters began to be used as terminals so multiple users could access the computer simultaneously. The operating system MULTICS was intended to allow hundreds of users to access a large computer. Despite its limited adoption, it can be considered the precursor to cloud computing . The UNIX operating system originated as
9315-408: The need to use it. A general protection fault would be produced, indicating a segmentation violation had occurred; however, the system would often crash anyway. The use of virtual memory addressing (such as paging or segmentation) means that the kernel can choose what memory each program may use at any given time, allowing the operating system to use the same memory locations for multiple tasks. If
9430-408: The open-source Android operating system (introduced 2008), with a Linux kernel and a C library ( Bionic ) partially based on BSD code, became most popular. The components of an operating system are designed to ensure that various parts of a computer function cohesively. With the de facto obsoletion of DOS , all user software must interact with the operating system to access hardware. The kernel
9545-561: The operating system dropped support for 32-bit processors in favor of being solely offered in 64-bit versions only. This effectively ended any association of MS-DOS within Microsoft Windows after 36 years. MS-DOS 6.22 was the last standalone version produced by Microsoft for Intel 8088 , Intel 8086 , and Intel 80286 processors, which remains available for download via their MSDN , volume license, and OEM license partner websites, for customers with valid login credentials. MS-DOS
9660-600: The period when Digital Research was competing in the operating system market some computers, like the Amstrad PC1512 , were sold with floppy disks for two operating systems (only one of which could be used at a time), MS-DOS and CP/M-86 or a derivative of it. Digital Research produced DOS Plus , which was compatible with MS-DOS 2.11, supported CP/M-86 programs, had additional features including multi-tasking, and could read and write disks in CP/M and MS-DOS format. While OS/2
9775-519: The peripheral hardware of the IBM PC architecture. This design would have worked well for compatibility, if application programs had only used MS-DOS services to perform device I/O. Indeed, the same design philosophy is embodied in Windows NT (see Hardware Abstraction Layer ). However, in MS-DOS' early days, the greater speed attainable by programs through direct control of hardware was of particular importance, especially for games, which often pushed
9890-421: The piping. Signals may be classified into 7 categories. The categories are: Input/output (I/O) devices are slower than the CPU. Therefore, it would slow down the computer if the CPU had to wait for each I/O to finish. Instead, a computer may implement interrupts for I/O completion, avoiding the need for polling or busy waiting. Some computers require an interrupt for each character or word, costing
10005-455: The platform without Microsoft and sold it as the alternative to DOS and Windows. As a response to Digital Research 's DR DOS 6.0 , which bundled SuperStor disk compression, Microsoft opened negotiations with Stac Electronics , vendor of the most popular DOS disk compression tool, Stacker. In the due diligence process, Stac engineers had shown Microsoft part of the Stacker source code. Stac
10120-428: The popular 1983 Radio Shack TRS-80 Model 100 , a non-PC-compatible machine, was comparably sized. It was a small battery-operated computer resting in one's lap, but had a 40×8 character (240×64 pixel) screen, a rudimentary ROM -based menu in lieu of a full OS , and no built-in floppy . IBM's 1984 Portable PC was comparable in capability with desktops, but was not battery operable and, being much larger and heavier,
10235-413: The price higher yet. The styling of the product, including a bag designed by Pierre Cardin , implied a more up-market buyer than many typical PC buyers of the time. The Data General/One also had a built-in dumb terminal emulator, suggesting an attempt to attract as customers those in organisations with large, expensive minicomputers or mainframes that would access corporate data via terminals such as
10350-492: The program at the prompt ( CMD.EXE , 4NT.EXE , TCC.EXE ), can see the output. 64-bit Windows has neither the DOS emulation, nor the DOS commands EDIT, DEBUG and EDLIN that come with 32-bit Windows. The DOS version returns 5.00 or 5.50, depending on which API function is used to determine it. Utilities from MS-DOS 5.00 run in this emulation without modification. The very early beta programs of NT show MS-DOS 30.00, but programs running in MS-DOS 30.00 would assume that OS/2
10465-418: The same operating system— OS/360 —which consisted of millions of lines of assembly language that had thousands of bugs . The OS/360 also was the first popular operating system to support multiprogramming , such that the CPU could be put to use on one job while another was waiting on input/output (I/O). Holding multiple jobs in memory necessitated memory partitioning and safeguards against one job accessing
10580-424: The same requests from customers that we have." – (Schulman et al. 1994). The pact between Microsoft and IBM to promote OS/2 began to fall apart in 1990 when Windows 3.0 became a marketplace success. Many of Microsoft's further contributions to OS/2 also went into creating a third GUI replacement for DOS, Windows NT . IBM, which had already been developing the next version of OS/2, carried on development of
10695-521: The shared features of its "single-user OS" and "the multi-user, multi-tasking , UNIX -derived operating system", and promising easy porting between them. After the breakup of the Bell System , however, AT&T Computer Systems started selling UNIX System V . Believing that it could not compete with AT&T in the Unix market, Microsoft abandoned Xenix, and in 1987 transferred ownership of Xenix to
10810-400: The signal number (in mnemonic format) to be sent. (The abrasive name of kill was chosen because early implementations only terminated the process.) In Unix-like operating systems, signals inform processes of the occurrence of asynchronous events. To communicate asynchronously, interrupts are required. One reason a process needs to asynchronously communicate to another process solves
10925-400: The size of the machine needed. The different CPUs often need to send and receive messages to each other; to ensure good performance, the operating systems for these machines need to minimize this copying of packets . Newer systems are often multiqueue —separating groups of users into separate queues —to reduce the need for packet copying and support more concurrent users. Another technique
11040-442: The system and may also include accounting software for cost allocation of processor time , mass storage , peripherals, and other resources. For hardware functions such as input and output and memory allocation , the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or
11155-401: The system. As MS-DOS 7.0 was a part of Windows 95, support for it also ended when Windows 95 extended support ended on December 31, 2001. As MS-DOS 7.10 and MS-DOS 8.0 were part of Windows 98 and Windows ME, respectively, support ended when Windows 98 and ME extended support ended on July 11, 2006, thus ending support and updates of MS-DOS from Microsoft. In contrast to the Windows 9x series,
11270-519: The systems they were designed for, and in any case were very similar in function and capability to some standard version for the IBM PC—often the same-numbered version, but not always, since some OEMs used their own proprietary version numbering schemes (e.g. labeling later releases of MS-DOS 1.x as 2.0 or vice versa)—with a few notable exceptions. Microsoft omitted multi-user support from MS-DOS because Microsoft's Unix -based operating system, Xenix ,
11385-474: The use of Win32 console applications and internal commands with an NTCMDPROMPT directive. Win32 console applications use CMD.EXE as their command prompt shell. This confusion does not exist under OS/2 because there are separate DOS and OS/2 prompts, and running a DOS program under OS/2 will launch a separate DOS window to run the application. All versions of Windows for Itanium (no longer sold by Microsoft) and x86-64 architectures no longer include
11500-478: The version customized for their hardware, or face trying to get all of their proprietary hardware and software to work with the new system. In the business world, the 808x-based machines that MS-DOS was tied to faced competition from the Unix operating system; the latter ran on many different hardware architectures. Microsoft itself sold a version of Unix for the PC called Xenix . In the emerging world of home users,
11615-612: The version number and the VER internal command reports as "Windows Millennium" and "5.1", respectively, and not as "MS-DOS 8.0" (which was used as the base for Windows Me but never released as a stand-alone product), though the API still says Version 8.0. The creation of the MS-DOS startup disk was then carried over to later versions of Windows, with the majority of its contents remaining unchanged from its introduction in Windows XP. When creating
11730-473: The world. Middleware , an additional software layer between the operating system and applications, is often used to improve consistency. Although it functions similarly to an operating system, it is not a true operating system. Embedded operating systems are designed to be used in embedded computer systems , whether they are internet of things objects or not connected to a network. Embedded systems include many household appliances. The distinguishing factor
11845-453: The x86 platform. Initially, MS-DOS was targeted at Intel 8086 processors running on computer hardware using floppy disks to store and access not only the operating system, but application software and user data as well. Progressive version releases delivered support for other mass storage media in ever greater sizes and formats, along with added feature support for newer processors and rapidly evolving computer architectures. Ultimately, it
11960-418: Was by no means a laptop. The DG-1 was only a modest success. One problem was its use of 3.5" diskettes. Popular software titles were thus not widely available (5.25" being still the standard), a serious issue since then-common diskette copy-protection schemes made it difficult for users to copy software into that format. The device achieved moderate success in a large OEM deal with Allen-Bradley , where it
12075-455: Was designed with a modular structure with internal device drivers (the DOS BIOS ), minimally for primary disk drives and the console, integrated with the kernel and loaded by the boot loader, and installable device drivers for other devices loaded and integrated at boot time. The OEM would use a development kit provided by Microsoft to build a version of MS-DOS with their basic I/O drivers and
12190-515: Was fully multi-user. The company planned, over time, to improve MS-DOS so it would be almost indistinguishable from single-user Xenix, or XEDOS , which would also run on the Motorola 68000 , Zilog Z8000 , and the LSI-11 ; they would be upwardly compatible with Xenix, which Byte in 1983 described as "the multi-user MS-DOS of the future". Microsoft advertised MS-DOS and Xenix together, listing
12305-552: Was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the graphical Microsoft Windows operating system. IBM licensed and re-released it in 1981 as PC DOS 1.0 for use in its PCs. Although MS-DOS and PC DOS were initially developed in parallel by Microsoft and IBM, the two products diverged after twelve years, in 1993, with recognizable differences in compatibility, syntax and capabilities. Beginning in 1988 with DR-DOS , several competing products were released for
12420-657: Was in control. The OS/2 emulation is handled through OS2SS.EXE and OS2.EXE, and DOSCALLS.DLL. OS2.EXE is a version of the OS/2 shell (CMD.EXE), which passes commands down to the OS2SS.EXE, and input-output to the Windows NT shell. Windows 2000 was the last version of NT to support OS/2. The emulation is OS/2 1.30. POSIX is emulated through the POSIX shell, but no emulated shell; the commands are handled directly in CMD.EXE. The Command Prompt
12535-474: Was private labelled as a T-45 "programming terminal" and was resold from 1987 to 1991 with thousands of units sold. The CPU was a CMOS version of the 8086, compatible with the IBM PC's 8088 except it ran slightly slower, at 4.0 MHz instead of the standard 4.77 MHz. Unlike the Portable PC, the DG-1 laptop could not take regular PC/XT expansion cards. RS-232 serial ports were built-in, but
12650-1212: Was released through the OEM channel, until Digital Research released DR-DOS 5.0 as a retail upgrade. With PC DOS 5.00.1, the IBM–Microsoft agreement started to end, and IBM entered the retail DOS market with IBM DOS 5.00.1, 5.02, 6.00 and PC DOS 6.1, 6.3, 7, 2000 and 7.1. Localized versions of MS-DOS existed for different markets. While Western issues of MS-DOS evolved around the same set of tools and drivers just with localized message languages and differing sets of supported codepages and keyboard layouts, some language versions were considerably different from Western issues and were adapted to run on localized PC hardware with additional BIOS services not available in Western PCs, support multiple hardware codepages for displays and printers, support DBCS, alternative input methods and graphics output. Affected issues include Japanese ( DOS/V ), Korean, Arabic (ADOS 3.3/5.0), Hebrew (HDOS 3.3/5.0), Russian ( RDOS 4.01 / 5.0 ) as well as some other Eastern European versions of DOS. On microcomputers based on
12765-507: Was seen as the legitimate heir to the "kludgy" DOS platform. MS-DOS had grown in spurts, with many significant features being taken or duplicated from Microsoft's other products and operating systems. MS-DOS also grew by incorporating, by direct licensing or feature duplicating, the functionality of tools and utilities developed by independent companies, such as Norton Utilities , PC Tools ( Microsoft Anti-Virus ), QEMM expanded memory manager, Stacker disk compression , and others. During
12880-406: Was the first popular computer to use a graphical user interface (GUI). The GUI proved much more user friendly than the text-only command-line interface earlier operating systems had used. Following the success of Macintosh, MS-DOS was updated with a GUI overlay called Windows . Windows later was rewritten as a stand-alone operating system, borrowing so many features from another ( VAX VMS ) that
12995-517: Was the key product in Microsoft's development from a programming language company to a diverse software development firm, providing the company with essential revenue and marketing resources. It was also the underlying basic operating system on which early versions of Windows ran as a GUI. MS-DOS went through eight versions, until development ceased in 2000; version 6.22 from 1994 was the final standalone version, with versions 7 and 8 serving mostly in
13110-506: Was under protracted development, Digital Research released the MS-DOS compatible DR-DOS 5.0, which included features only available as third-party add-ons for MS-DOS. Unwilling to lose any portion of the market, Microsoft responded by announcing the "pending" release of MS-DOS 5.0 in May 1990. This effectively killed most DR DOS sales until the actual release of MS-DOS 5.0 in June 1991. Digital Research brought out DR DOS 6.0, which sold well until
13225-592: Was unwilling to meet Microsoft's terms for licensing Stacker and withdrew from the negotiations. Microsoft chose to license Vertisoft's DoubleDisk, using it as the core for its DoubleSpace disk compression. MS-DOS 6.0 and 6.20 were released in 1993, both including the Microsoft DoubleSpace disk compression utility program. Stac successfully sued Microsoft for patent infringement regarding the compression algorithm used in DoubleSpace. This resulted in
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