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Virtual 8086 Mode
In the 80386 microprocessor and later, virtual 8086 mode (also called virtual real mode, V86-mode, or VM86) allows the execution of real mode applications that are incapable of running directly in protected mode while the processor is running a protected mode operating system. It is a hardware virtualization technique that allowed multiple 8086 processors to be emulated by the 386 chip. It emerged from the painful experiences with the 80286 protected mode, which by itself was not suitable to run concurrent real-mode applications well. John Crawford developed the Virtual Mode bit at the register set, paving the way to this environment. VM86 mode uses a segmentation scheme identical to that of real mode (for compatibility reasons), which creates 20-bit linear addresses in the same manner as 20-bit physical addresses are created in real mode, but are subject to protected mode's memory paging mechanism. Overview The virtual 8086 mode is a mode for a protected-mode task. Conseq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intel 80386
The Intel 386, originally released as the 80386 and later renamed i386, is the third-generation x86 architecture microprocessor from Intel. It was the first 32-bit computing, 32-bit processor in the line, making it a significant evolution in the x86 architecture. Pre-production samples of the 386 were released to select developers in 1985, while mass production commenced in 1986. The 386 was the central processing unit, central processing unit (CPU) of many workstations and high-end personal computers of the time. The 386 began to fall out of public use starting with the release of the i486 processor in 1989, while in embedded systems the 386 remained in widespread use until Intel finally discontinued it in 2007. Compared to its predecessor the Intel 80286 ("286"), the 80386 added a three-stage instruction pipelining, instruction pipeline which it brings up to total of 6-stage instruction pipeline, extended the architecture from 16-bits to 32-bits, and added an on-chip memory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiuser DOS
Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers. An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by Digital Research and acquired and further developed by Novell in 1991. Its ancestry lies in the earlier Digital Research 8-bit operating systems CP/M and MP/M, and the 16-bit single-tasking CP/M-86 which evolved from CP/M. When Novell abandoned Multiuser DOS in 1992, the three master value-added resellers (VARs) DataPac Australasia, Concurrent Controls and Intelligent Micro Software were allowed to take over and continued independent development into Datapac Multiuser DOS and System Manager, CCI Multiuser DOS, and IMS Multiuser DOS and REAL/32. The FlexOS line, which evolved from Concurrent DOS 286 and Concurrent DOS 68K, was sold off to Integrated Systems, Inc. (ISI) in July 1994. Concurrent CP/M-86 The initial version of C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual DOS Machine
Virtual DOS machines (VDM) refer to a technology that allows running 16-bit/32-bit DOS and 16-bit Windows programs when there is already another operating system running and controlling the hardware. Overview Virtual DOS machines can operate either exclusively through typical software emulation methods (e.g. dynamic recompilation) or can rely on the virtual 8086 mode of the Intel 80386 processor, which allows real mode 8086 software to run in a controlled environment by catching all operations which involve accessing protected hardware and forwarding them to the normal operating system (as exceptions). The operating system can then perform an emulation and resume the execution of the DOS software. VDMs generally also implement support for running 16-bit and 32-bit protected mode software (DOS extenders), which has to conform to the DOS Protected Mode Interface (DPMI). When a DOS program running inside a VDM needs to access a peripheral, Windows will either allow this direc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOSEMU
DOSEMU, stylized as dosemu, is a compatibility layer software package that enables DOS operating systems (e.g., MS-DOS, DR-DOS, FreeDOS) and application software to run atop Linux on x86-based PCs (IBM PC compatible computers). Features It uses a combination of hardware-assisted virtualization features and high-level emulation. It can thus achieve nearly native speed for 8086-compatible DOS operating systems and applications on x86 compatible processors, and for DOS Protected Mode Interface (DPMI) applications on x86 compatible processors as well as on x86-64 processors. DOSEMU includes an 8086 processor emulator for use with real-mode applications in x86-64 long mode. DOSEMU is only available for x86 and x86-64 Linux systems (Linux 3.15 x86-64 systems cannot enter DPMI by default. This is fixed in 3.16). 140715 bugs.debian.org DOSEMU is an option for people who need or want to continue to use legacy DOS software; in some cases virtualisation is good enough to drive exter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, packaged as a Linux distribution (distro), which includes the kernel and supporting system software and library (computing), libraries—most of which are provided by third parties—to create a complete operating system, designed as a clone of Unix and released under the copyleft GPL license. List of Linux distributions, Thousands of Linux distributions exist, many based directly or indirectly on other distributions; popular Linux distributions include Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu, while commercial distributions include Red Hat Enterprise Linux, SUSE Linux Enterprise, and ChromeOS. Linux distributions are frequently used in server platforms. Many Linux distributions use the word "Linux" in their name, but the Free ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merge (software)
Merge is a software system which allows a user to run DOS/ Windows 3.1 on SCO UNIX, in an 8086 virtual machine. History Merge was originally developed to run DOS under UNIX System V Release 2 on an AT&T 6300 Plus personal computer. Development of the virtual machine began in late 1984, and AT&T announced the availability of the machine on 9 October 1985, referring to the bundled Merge software as Simultask. (The PC 6300 Plus shipped with MS-DOS in 1985 though, because its Unix System V distribution was not ready until the end of March 1986.) Merge was developed by engineers at Locus Computing Corporation, with collaboration from AT&T hardware and software engineers, particularly on aspects of the system that were specific to the 6300 Plus (in contrast to a standard IBM PC/AT). The AT&T 6300 Plus contained an Intel 80286 processor, which did not include the support for 8086 virtual machines ( virtual 8086 mode) found in the 80386 and later processors in the x86 fami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SCO UNIX
Xinuos OpenServer, previously SCO UNIX and SCO Open Desktop (SCO ODT), is a closed source computer operating system developed by Santa Cruz Operation (SCO), later acquired by SCO Group, and now owned by Xinuos. Early versions of OpenServer were based on UNIX System V, while the later OpenServer 10 is based on FreeBSD 10. However, OpenServer 10 has not received any updates since 2018 and is no longer marketed on Xinuos's website, while OpenServer 5 Definitive and 6 Definitive are still supported. History SCO UNIX/SCO Open Desktop In 1987 AT&T Corporation, Microsoft, and Sun Microsystems agreed to combine their versions of the Unix operating system. Santa Cruz Operation (SCO) sublicensed Microsoft's Xenix and wanted to retain the Xenix name, but AT&T said "If they want to call it Unix, they've got to use it the way it is. We don't want another set of variants". SCO UNIX was the successor to Xenix, derived from UNIX System V Release 3.2 with an infusion of Xenix device drivers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual DOS Machine
Virtual DOS machines (VDM) refer to a technology that allows running 16-bit/32-bit DOS and 16-bit Windows programs when there is already another operating system running and controlling the hardware. Overview Virtual DOS machines can operate either exclusively through typical software emulation methods (e.g. dynamic recompilation) or can rely on the virtual 8086 mode of the Intel 80386 processor, which allows real mode 8086 software to run in a controlled environment by catching all operations which involve accessing protected hardware and forwarding them to the normal operating system (as exceptions). The operating system can then perform an emulation and resume the execution of the DOS software. VDMs generally also implement support for running 16-bit and 32-bit protected mode software (DOS extenders), which has to conform to the DOS Protected Mode Interface (DPMI). When a DOS program running inside a VDM needs to access a peripheral, Windows will either allow this direc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windows ME
Windows Me (Millennium Edition) is an operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It was the successor to Windows 98, and was released to manufacturing on June 19, 2000, and then to retail on September 14, 2000. It was Microsoft's main operating system for home users until the introduction of its successor Windows XP on October 25, 2001. Windows Me was targeted specifically at home PC users, and included Internet Explorer 5.5 (which could later be upgraded to Internet Explorer 6), Windows Media Player 7 (which could later be upgraded to Windows Media Player 9 Series), DirectX 7 (which could later be upgraded to DirectX 9) and the new Windows Movie Maker software, which provided basic video editing and was designed to be easy to use for consumers; it is the last MS-DOS-based Windows version as all consumer versions starting with Windows XP moved to the Windows NT kernel. Microsoft also incorporated features ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windows 98 SE
Windows 98 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It was the second operating system in the 9x line, as the successor to Windows 95. It was released to manufacturing on May 15, 1998, and generally to retail on June 25, 1998. Like its predecessor, it is a hybrid 16-bit and 32-bit monolithic product with the boot stage based on MS-DOS. Windows 98 is web-integrated and bears numerous similarities to its predecessor. Most of its improvements were cosmetic or designed to improve the user experience, but there were also a handful of features introduced to enhance system functionality and capabilities, including improved USB support and accessibility, and support for hardware advancements such as DVD players. Windows 98 was the first edition of Windows to adopt the Windows Driver Model, and introduced features that would become standard in future generations of Windows, such as Disk Cleanup, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windows 95
Windows 95 is a consumer-oriented operating system developed by Microsoft and the first of its Windows 9x family of operating systems, released to manufacturing on July 14, 1995, and generally to retail on August 24, 1995. Windows 95 merged Microsoft's formerly separate MS-DOS and Microsoft Windows products into a single product and featured significant improvements over its predecessor, most notably in the graphical user interface (GUI) and in its simplified " plug-and-play" features. There were also major changes made to the core components of the operating system, such as moving from a mainly cooperatively multitasked 16-bit architecture of its predecessor Windows 3.1 to a 32-bit preemptive multitasking architecture. Windows 95 introduced numerous functions and features that were featured in later Windows versions, and continue in modern variations to this day, such as the taskbar, the notification area, file shortcuts on the desktop, plug and play driver integration, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
