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147-410: 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 ) 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

294-458: 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

441-428: 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

588-617: 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

735-448: 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

882-515: 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

1029-469: A Tandy 2000. It was standard practice and Microsoft's expectation at the time that a customized version of MS-DOS would be prepared for each different machine, with I/O drivers designed for the hardware of that model. The highest version of DOS that Tandy Corporation released for the Tandy 2000 was 2.11.03, with a few minor third-party patches after the fact. A modified version of Windows 1.0 was able to run on

1176-492: A better computer. The new machine would be aimed at the mid-price market between high-end consumers and low-end businesses. This was deemed prudent in order not to seriously cannibalize their current product lines serving both market segments. Most other big-name computer manufacturers made the same leap into the PC/MS-DOS market: Shortly after IBM's introduction of its 286-based PC/AT , one reviewer remarked, "The bottom line

1323-461: A bootable 3.5-inch system disk using an ordinary 720 KB 3.5-inch PC drive; this will boot a Tandy 2000 if its 5.25" boot drive has been replaced with a double-density 720 KB 3.5 inch PC drive. The keyboard was a new design made for the Tandy 2000. It would later be the same keyboard shipped with the Tandy 1000 and its successors. The arrangement of the function keys was changed from that of

1470-645: 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

1617-754: 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,

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1764-585: 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

1911-483: A dual-drive floppy-only model for $ 2,750 and the 2000HD with a single floppy drive and a half-height 10 MB hard drive for $ 4,250 . The dual-floppy model had 128 KB RAM and the hard-drive-equipped 2000HD had 256 KB. For comparison, at this time the low-end TRS-80 Model 4 with two floppy drives cost $ 1,999 and the high-end Model 16 with two floppy drives cost $ 4,699 . Tandy executive Ed Juge said that within six months Tandy realized that it had erred with

2058-541: 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

2205-456: A functional installation, none of the T2000's special features would be operative (except for increased speed and storage). The only version of Lotus 1-2-3 offered for the Tandy 2000 was Release 1A. This was customized to take advantage of the unique hardware of the computer, including its full 768K of RAM, high resolution color graphics, and two extra function keys. Release 1A's executable code

2352-566: A high-performance PC was the origin of the Tandy 2000's technical specifications. Some of the rival computers improved the PC hardware and matched the Tandy 2000 in one or two dimensions, but none offered across-the-board enhancement. Except as noted, they ran MS-DOS but were incompatible with the IBM PC at the hardware level. The copycat computers competed primarily on lower pricing and, like Tandy, exploiting their installed customer bases. Tandy described

2499-448: 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

2646-484: 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,

2793-458: 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

2940-442: 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

3087-528: A little more than a year later (October 1984), the Microsoft BASIC interpreter would not support its greater color and resolution capabilities until 1988. Tandy/Radio Shack produced print advertising featuring Bill Gates of Microsoft extolling the superior performance of the Tandy 2000 and how it was advantageous in Microsoft's development of Windows 1.0. Software packages that were released for

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3234-447: 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,

3381-472: A palette of sixteen available colors were displayable on the Tandy CM-1 monitor (~$ 799). This was a particularly high-resolution and colorful display for its day. The CM-1 accepted, as input from the color graphics board, digital RGBI signals (indicating separate Red, Green, and Blue signals with an Intensity bit). CGA compatibility was hit-or-miss. There were only three non-Tandy monitors that worked with

3528-455: 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

3675-407: 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

3822-503: 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

3969-408: 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

4116-440: 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

4263-470: 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

4410-402: 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

4557-462: 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

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4704-590: A standard-setter for small computers, and most other established manufacturers shifted focus to it as well. By this date Tandy/Radio Shack had been in the small-computer market for four years, since its August 1977 introduction of the TRS-80 Model I . The new computer division followed in October 1979 with the TRS-80 Model II —a high-end business-oriented system. In 1983 the TRS-80 Model 4 succeeded

4851-417: 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

4998-453: 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

5145-549: 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

5292-450: 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

5439-456: 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

5586-418: 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

5733-562: 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

5880-484: 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

6027-500: 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 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,

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6174-407: Is also why so many of the other PC-style computers by other manufacturers were not hardware-compatible with the IBM PC. Though the company supported the machine with hardware add-ons and software tailored specially for it (including bestsellers like Lotus 1-2-3 Release 1A and AutoCAD ), the computer failed to gain popular acceptance and was never developed further. It would not be until late 1986, with

6321-422: 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

6468-896: 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

6615-411: 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

6762-518: 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

6909-443: 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

7056-439: 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,

7203-499: 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,

7350-468: Is that the Tandy 2000 is still one of the hottest single-user machines on the market, and a full year after its introduction, its superiority remains unchallenged." Applications software compatible with the MS-DOS operating system would run properly on the Tandy 2000. This means that the software had to access the computer's hardware (particularly the video display) strictly through calls to the operating system's BIOS . However, programs written to run under

7497-473: 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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7644-435: 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 ,

7791-542: 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

7938-504: 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

8085-591: 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

8232-577: 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

8379-420: 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

8526-693: 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

8673-451: 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

8820-431: The 2000 as having a "'next generation' true 16-bit CPU", and with "More speed. More disk storage. More expansion" than the IBM PC or "other MS-DOS computers". While admitting in 1984 that many MS-DOS programs did not support the computer, the company stated that "the most popular, sophisticated software on the market" was available, either immediately or "over the next six months". Two models of Tandy 2000 were introduced:

8967-499: The 2000. By early 1985 InfoWorld reported that Tandy introduced the Tandy 1000 because it "found that the market prefers true PC compatibility" to the 2000's incomplete compatibility. The Tandy 2000 received a lukewarm welcome by the market and the computer press because of its inability to run most popular MS-DOS applications. This was not anticipated by Tandy because, at the time, it was accepted practice for new software to be created for each new computer that came to market. This

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9114-688: The 640 KB limit imposed by the IBM architecture. It used 80-track double-sided quad-density floppy drives of 720 KB capacity; the IBM standard at the time of the introduction of the Tandy 2000 was only 360 KB. The Tandy 2000 had both "Tandy" and "TRS-80" logos on its case, marking the start of the phaseout of the "TRS-80" brand. The introduction of IBM 's Model 5150 Personal Computer in August 1981 created an entirely new market for microcomputers. Many hardware and software companies were founded specifically to exploit IBM's and Microsoft 's new presence as

9261-569: 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

9408-410: 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

9555-474: 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

9702-560: 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

9849-473: 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

9996-599: The IBM PC was introduced, the nearest thing to an industry standard in small computers was CP/M-80; no single manufacturer dominated. By 1983 the IBM PC, and Tandy's discouraging of third-party products, had halved the company's market share and stopped profit growth. Tandy's motive for moving into the new MS-DOS domain was twofold: to capitalize on the new market, and to leverage sales opportunities afforded by their solid position in small computers. Marketing management believed that many Tandy customers would prefer to stay with Tandy products when (inevitably, it seemed) they made

10143-613: The IBM PC/XT, which had ten on the left side of the keyboard in two columns of five. Tandy was among the first PC manufacturers to change this to the modern arrangement of twelve function keys arranged horizontally across the top. IBM gave a nod to the new standard by using this arrangement for the Model M keyboard . The serial port hardware was completely different from the PC/XT's. PC-compatible terminal emulation software had to either access

10290-470: 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

10437-434: 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

10584-647: The Model III (which itself had replaced the Model I) in the consumer and educational markets. In the business segment the TRS-80 Model 12 and Model 16 succeeded the Model II, adding higher-end features. Thus far Tandy/Radio Shack's computer lines occupied their own niches in the market because of their proprietary system software and applications. Tandy attempted to monopolize software and peripheral sales by not offering third-party products in company stores. Until

10731-405: 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

10878-549: 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

11025-536: The PC-compatible text-mode memory to the Tandy 2000's text space at a rate of 5–10 times per second. This sometimes caused some choppiness in the display. It produced a fast text display rate—often too fast to read—but the 'HOLD' key on the keyboard could be used to pause text output. The bit pattern for each text character's raster image was maintained in RAM and could be modified by the user. With clever programming

11172-452: The Tandy 2000 Orphans, with software reviews, software and hardware hacks, and a shareware/freeware repository. It was discovered by amateur programmers that many commercial MS-DOS applications needed only minor modifications to function on the Tandy 2000's unique hardware. There was also a BBS based in Texas that had an extensive library of compatible software available for download; neither

11319-487: The Tandy 2000 and the PC was used to write BBS software for the Tandy 2000 and later ported to the IBM PC. Radio Shack's DeskMate was also used with the Tandy 2000 and the Tandy 1000. MicroPro's Wordstar (versions 3.3 and 4.0 only) would run on the Tandy 2000 provided the user ran the WINSTALL installation utility and, when prompted for the type of video display to be used, selected "ROM BIOS". While this would result in

11466-597: The Tandy 2000 graphics card, all of which are long out of production. These were the original (1986–88) Mitsubishi Diamond Scan, and the NEC Multisync and Multisync GS (grayscale). The required horizontal scan frequency for the Tandy 2000 is 26.4 kHz. Modern flat-panel multisync computer monitors cannot sync at frequencies below 30 kHz. The CM-1 monitor is also digital RGB; all modern CRT monitors are analog-only. The Tandy 2000 used quad-density 5.25" floppy disks formatted at 720k. This format (80-track disks at

11613-435: The Tandy 2000 included WordPerfect 4.2 (WP5.1 could work with software patches), Lotus 1-2-3 , Ashton-Tate's Framework , DBase , MultiMate , Pfs:Write , AutoCAD , Lumena (from Time Arts) shareware office programs, and the complete line of Microsoft language products. Microsoft released a version of Xenix for the Tandy 2000 (used with Western Digital's ViaNet network card, distributed by Tandy). Better BASIC for both

11760-432: The Tandy 2000 is compatible with 3.5" double-density 720 KB floppy drives. As of May 2019, there is an abandonware site (winworldpc.com) that has available for download a disk image for the latest version of MS-DOS for the Tandy 2000. It includes instructions for using the IBM 1.2 MB 5.25" disk drive (80-track) to create a system disk bootable in the Tandy 2000 5.25" drive. This procedure can also be used to create

11907-475: The Tandy 2000 that had hardware that differed in its details from an IBM PC would not execute programs the same way, which most often manifested incorrect results by those programs. Tandy engineers tested one hundred of the most popular PC programs and half were found to be incompatible with the 2000's hardware. Tandy's marketing department failed to appreciate that similar non-compatible computers from DEC, TI and Eagle were not successful. Its strategy of offering

12054-544: The Tandy 2000 was the top performer for processing large models in Lotus 1-2-3. The Tandy 2000's 720 KB floppy drives were a distinct advantage for running Lotus, because they were large enough to store even the largest worksheets on a single diskette. This is in stark contrast to the IBM PC and XT with 360 KB floppy disks. In order to store the largest worksheets, a PC user would have to split them and save them on two disks—and then recombine them in memory later. Although

12201-485: The Tandy 2000's disks. Much like 1.2 MB drives, the Tandy 2000 had problems reliably writing 360k PC disks due to the smaller heads not completely erasing the tracks and causing 40-track drives to become confused by residual magnetic signals on the outer edge of the track. Tandy distributed the computer with a utility called PC-Maker that would read and format 40-track disks in the 2000s 80-track drives, and were readable in drives on ordinary PCs. The floppy controller on

12348-717: The Tandy 2000. MS-DOS for the Tandy 2000 resided entirely in RAM, unlike on IBM PCs where the BIOS portion of the OS resided in ROM. The complete MS-DOS system (BIOS and BDOS) occupied about 53 KB of RAM. This means that the RAM required to run applications on the Tandy 2000 was a little greater. However, the Tandy 2000 fared better in comparison to the later IBM PC-AT in that the AT was required to run MS-DOS version 3.x in order to operate its 1.2 MB floppy drives and hard drive. Version 3 of MS-DOS

12495-520: 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

12642-470: The XT had a hard drive that could store large Lotus worksheets in a single file, a user could not rely on a single storage device for permanent storage of important data files; again they would be forced to segment worksheets for storage on separate disks. The Tandy 2000's large-capacity floppy disks made backup maintenance relatively effortless. After Tandy dropped support of the Tandy 2000, a group of users formed

12789-538: 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

12936-422: 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

13083-495: 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

13230-655: 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

13377-453: 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

13524-453: 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

13671-471: 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

13818-416: The display's ability to present fine lines provided by the 640x400 screen resolution could be accessed in text mode even without the optional graphics board. The display was upgradable to support pixel-addressable graphics via the Tandy 2000 Graphics Adapter, a circuit board that fit into an expansion slot. It had its own connector for the monochrome VM-1 monitor; the video connector in the rear-panel cabinet

13965-624: The double-density bitrate) was not used by PC-compatibles, although some CP/M machines and the Commodore 8050 /8250 drives had them. Normal PCs of the time had 40-track double-density floppy drives and could not read quad-density due to the drive heads being too wide to read the narrower tracks. 1.2 MB 5.25" drives (introduced on the IBM AT) could read quad-density disks because they were 80-track and had thinner heads. Various utility programs for DOS existed that could read nonstandard formats such as

14112-422: 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

14259-483: The hardware (especially video and external ports) to achieve higher performance. This rendered such software incompatible with the Tandy 2000. The base-model Tandy 2000 supported only a text-mode display in monochrome. The Tandy VM-1 monitor used the 8-pin DIN video port on the computer's rear panel. The text-mode address space was in a different location but third-party memory-resident software hacks remedied this by copying

14406-410: 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

14553-493: 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

14700-511: 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

14847-418: 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

14994-404: 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

15141-643: 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

15288-399: The introduction of the Tandy 3000 , that Tandy offered a PC-style computer with performance comparable with the Tandy 2000. The Tandy 2000 was marketed through early 1988 with continual price cuts. Eventually they were closed out for $ 999 and the remaining unsold computers were converted into Radio Shack store operations terminals (which, coincidentally, had been one of the backup plans for

15435-449: The jump onto the burgeoning IBM/Microsoft bandwagon; it was figured that the company was well-positioned in this regard because of its large base of customers in both the consumer and business markets (with its Z80-based TRS-80 Models I/III/4 and 68000-based Models 12 and 16, respectively). Tandy's large presence as a computer retailer, with several thousand Radio Shack stores throughout the US,

15582-431: 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

15729-685: 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

15876-402: 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

16023-400: 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

16170-408: 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

16317-408: 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

16464-560: 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

16611-460: The original TRS-80 Model I). Four card slots on the back could accept expansion boards without any need to open the case, using a rail system. Available expansion boards/cards included: The Tandy 2000 was nominally BIOS-compatible with the IBM XT, so well-behaved DOS software ran on both platforms. However, most DOS software of the time bypassed the operating system and BIOS and directly accessed

16758-600: 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

16905-519: 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

17052-421: 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

17199-455: 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

17346-492: 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

17493-490: The programmer or the user with the perception that there is a much larger amount of RAM in the computer than is really there. Tandy 2000 While touted as being compatible with the IBM XT , the Tandy 2000 was different enough that most existing PC software that was not purely text-oriented failed to work properly. The Tandy 2000 and its special version of MS-DOS supported up to 768 KB of RAM, significantly more than

17640-418: 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

17787-423: 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

17934-495: The serial hardware strictly through BIOS or use a FOSSIL driver, a software wrapper that virtualized the serial hardware (see also DEC Rainbow ), to run on a wider variety of hardware. Several terminal programs were available for the Tandy 2000, making it possible to log in on BBSes , e-mail, and other remote systems. The Tandy 2000 required a specific version of MS-DOS that would run only on this machine. Standard MS-DOS or PC DOS (for generic IBM-compatibles) would not run on

18081-520: 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

18228-400: 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

18375-464: The similar PC DOS operating system on an actual IBM PC computer often bypassed calls to the operating system because the IBM BIOS was poorly designed and implemented. To function with adequate speed of execution, and to perform operations not provided for by the IBM BIOS, applications programmers often coded their programs to directly address the hardware of the IBM PC. Therefore any computer such as

18522-400: 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

18669-442: 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

18816-566: 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, the Windows NT -derived 32-bit operating systems ( Windows NT , 2000 , XP and newer), developed alongside

18963-519: 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 ,

19110-660: 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 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

19257-474: 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

19404-478: 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,

19551-612: 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

19698-473: 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

19845-400: Was about 60 KB smaller than the later Release 2, which provided greater macro programming facilities. This extra space for data, with the additional 128 KB of RAM available to a fully expanded Tandy 2000, made it possible to construct larger worksheets than later PCs running Release 2 (until the advent of machines with Expanded memory ). For nearly two years following its introduction,

19992-508: Was deemed an advantage as well. All other PC manufacturers, especially IBM, relied mainly on sales to corporate accounts, not consumer retail as did Tandy/Radio Shack. Thus the company would become the market leader offering the hottest new trend—affordable 16-bit computers running MS-DOS—directly to the computing public. Therefore, Tandy would have to produce an IBM-style computer running the emerging industry-standard MS-DOS. The company decided to distinguish it from similar products by producing

20139-455: 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

20286-486: Was disabled when this expansion board was installed. The graphics resolution was 640x400 and supported high intensity pixels. Color capability was provided by the Color Graphics Option, which was a set of chips that were inserted into the empty sockets on the monochrome Graphics Adapter provided for this purpose. Resolution for the color board was the same 640x400, non-interlaced, and eight colors out of

20433-512: 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

20580-657: 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

20727-505: Was rather larger than Version 2.x running on the Tandy 2000. It also proved advantageous that the Tandy 2000's OS resided entirely in RAM and therefore could be updated and hacked with rather less effort. The Microsoft BASIC interpreter was supplied with the computer. It was highly customized for the Tandy 2000 hardware, particularly its high-resolution color graphics. Although IBM produced the Enhanced Graphics Adapter

20874-1211: 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

21021-507: 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

21168-406: 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

21315-460: 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

21462-506: 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

21609-591: 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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