DOSEMU
Encyclopedia
DOSEMU, alternatively rendered dosemu, is a compatibility layer
Compatibility layer
A compatibility layer is a term that refers to components that allow for non-native support of components.In software engineering, a compatibility layer allows binaries for a legacy or foreign system to run on a host system. This translates system calls for the foreign system into native system...

 software package that enables MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...

 systems, DOS clones such as FreeDOS
FreeDOS
FreeDOS is an operating system for IBM PC compatible computers. FreeDOS is made up of many different, separate programs that act as "packages" to the overall FreeDOS Project...

, and DOS software to run under Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

 on x86-based PCs (IBM PC compatible
IBM PC compatible
IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

 computers).

It uses a combination of hardware virtualization features and strategic emulation. It is thus able to achieve nearly native speed for 8086-compatible DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...

 operating systems and applications on x86 compatible processors, and for 32-bit DPMI applications on x86 compatible processors as well as on x86-64
X86-64
x86-64 is an extension of the x86 instruction set. It supports vastly larger virtual and physical address spaces than are possible on x86, thereby allowing programmers to conveniently work with much larger data sets. x86-64 also provides 64-bit general purpose registers and numerous other...

 processors (Virtual 8086 mode
Virtual 8086 mode
In the 80386 microprocessor and later, virtual 8086 mode 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.VM86 mode uses a segmentation scheme identical to that of real mode In...

 is not available in x86-64 long mode
Long mode
In the x86-64 computer architecture, long mode is the mode where a 64-bit application can access 64-bit instructions and registers...

, so DOSEMU includes an 8086 processor emulator for use with 16-bit applications.).

Currently it is only available for x86 Linux systems.

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 external hardware such as EPROM programmers
Programmer (hardware)
In field of computer hardware, the term programmer, chip programmer or device programmer refers to a hardware device that configures programmable non-volatile circuits such as EPROMs, EEPROMs, Flashs, PALs, FPGAs or programmable logic circuits....

 connected to the parallel port
Parallel port
A parallel port is a type of interface found on computers for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port...

. To quote the manual, "dosemu" is a user-level program which uses certain special features of the Linux kernel and the 80386 processor to run MS-DOS, FreeDOS or DR-DOS in what people in the biz call a `DOS box.' The DOS box, a combination of hardware and software trickery, has these capabilities:
  • Virtualize all input/output and processor control instructions
  • Supports the word size and addressing modes of the iAPX86 processor family's "real mode," while still running within the full protected mode environment
  • Trap all DOS
    Disk operating system
    Disk Operating System and disk operating system , most often abbreviated as DOS, refers to an operating system software used in most computers that provides the abstraction and management of secondary storage devices and the information on them...

     and BIOS system calls and emulate such calls as are necessary for proper operation and good performance
  • Simulate a hardware environment over which DOS programs are accustomed to having control.
  • Provide DOS services through native Linux services; for example, dosemu can provide a virtual hard disk drive which is actually a Linux directory hierarchy.
  • Packet driver
    PC/TCP Packet Driver
    PC/TCP Packet Driver is an API created in 1986 by FTP Software for network cards under x86-DOSes like MS-DOS, DR-DOS, FreeDOS, etc. It uses the x86 interrupt number between 60h .. 80h. The exact number is detected at run-time...

     API
    Application programming interface
    An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...

     for 3Com 3C503.

See also

  • Comparison of platform virtual machines
  • Virtual DOS machine
    Virtual DOS machine
    Virtual DOS machine is Microsoft's technology that allows running legacy DOS and 16-bit Windows programs on Intel 80386 or higher computers when there is already another operating system running and controlling the hardware.-Overview:...

  • DOSBox
    DOSBox
    DOSBox is emulator software that emulates an IBM PC compatible computer running MS-DOS. It is intended especially for use with old PC games. DOSBox is free software....

  • Wine
    Wine (software)
    Wine is a free software application that aims to allow computer programs written for Microsoft Windows to run on Unix-like operating systems. Wine also provides a software library, known as Winelib, against which developers can compile Windows applications to help port them to Unix-like...

  • FreeDOS
    FreeDOS
    FreeDOS is an operating system for IBM PC compatible computers. FreeDOS is made up of many different, separate programs that act as "packages" to the overall FreeDOS Project...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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