x86

Besides the CPU the following is emulated:

* CD-ROM/DVD-drive using an ISO-Image

* Floppy disk

* Graphics card (”Cirrus CLGD 5446 PCI VGA”-card or standard-VGA-Graphics card with Bochs-VESA-BIOS-Extensions& – Hardware level, including all non-standard modes, and with an experimental patch simple 3D via OpenGL)

* Network card (RealTek 8139C+ PCI-Network adapter) and a DHCP-server

* Parallel port

* PC speaker

* Two PCI-ATA-interfaces with a maximum of four hard disk drive images either in its own format or in VMware, VirtualPC, Bochs, Knoppix (cloop) or ”dd” (rawformat)

* PCI and ISA-system (”i440FX host PCI bridge” and ”PIIX3 PCI to ISA bridge”)

* PS/2-mouse and -keyboard

* Serial interface

* Sound card (Soundblaster 16, ES1370 PCI, and/or GUS)

* USB-controller (Intel SB82371, UHCI)

The BIOS implementation used by QEMU starting from version 0.12 is SeaBIOS. The VGA BIOS implementation comes from Plex86/Bochs.

PowerPC

On the PowerPC target, ”Open Hack’Ware”, an Open-Firmware-compatible BIOS, is used.

PowerMac

QEMU emulates the following PowerMac peripherals:

* UniNorth PCI Bridge

* PCI-VGA-compatible Graphics card which maps the ”VESA Bochs Extensions”

* Two PMAC-IDE-Interfaces with hard disk and CD-ROM support.

* NE2000 PCI Adapter

* Non Volatile RAM

* VIA-CUDA with ADB keyboard and mouse.

PREP

QEMU emulates the f

* PCI Bridge

* PCI-VGA-compatible graphics card with ”VESA Bochs Extensions”

* Two IDE-Interfaces with hard disk and CD-ROM support

* Floppy drive

* NE2000 network adapter

* Serial interface

* PREP Non Volatile RAM

* PC-compatible keyboard and mouse

ARM

QEMU emulates the armv5tej instruction set and all the derivative processors families like ARM7, ARM9E, ARM10E and XScale. It emulates full systems like Integrator/CP board, Versatile baseboard, RealView Emulation baseboard, XScale-based PDAs, Palm Tungsten|E PDA, Nokia N800 and Nokia N810 internet tablets etc.

SPARC

Sun SPARC-Architecture = (Scalable Processor ARChitecture)

When the BIOS in the JavaStation (sun4m-Architecture) became Version 0.8.1 ”Proll” , a PROM replacement, used, in Version 0.8.2 was replaced with OpenBIOS.

Sparc32

QEMU emulates the following ”sun4m/sun4c/sun4d” peripherals:

* IOMMU or IO-UNITs

* TCX Frame buffer (graphics card)

* Lance Ethernet

* Non Volatile RAM M48T02/M48T08

* Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboard and power/reset logic

* ESP SCSI controller with hard disk and CD-ROM support

* Floppy drive (not on SS-600MP)

* CS4231 sound device (only on SS-5, not working yet)

Sparc64

Emulating Sun4u (UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic Niagara (T1) machine with the following peripherals:

* UltraSparc IIi APB PCI Bridge

* PCI VGA compatible card with VESA Bochs Extensions

* PS/2 mouse and keyboard

* Non Volatile RAM M48T59

* PC-compatible serial ports

* 2 PCI IDE interfaces with hard disk and CD-ROM support

* Floppy disk

Microblaze

Supported peripherals:

* Microblaze with/without MMU

* timer

* intc

* uartlite

* emaclite

CRIS=

External patches

External trees exist supporting the following targets:

* Zilog Z80 emulating a Sinclair 48K ZX Spectrum

* HP PA-RISC

Adapted from the Wikipedia article QEMU, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Some live CDs come with an installation utility launchable from a desktop icon that can optionally install the system on a hard drive or USB flash drive. Most live CDs can access the information on internal and/or external hard drives, diskettes and USB flash drives.

Generally live CDs are booted from read-only media, requiring either copying to rewriteable media (i.e. a hard drive) or complete remastering to install additional software; however, there are exceptions such as Morphix and Puppy Linux which are one of the few Linux live CD distributions able to save files to the live CD itself or other multisession medium, allowing users to carry data, and more importantly, added programs and customized settings, along with them on optical disc.

Most live CDs are based on Linux, as this was the operating system that had the most to gain by offering free trials and demonstrations without regard to sales or copyright. Now others are using the term ”live CD” for other operating systems, such as OpenSolaris, BeleniX and others based on Solaris. Other “live” operating systems include Mac OS, Microsoft Windows, OS/2, ReactOS, NetBSD, FreeBSD, OpenBSD, MINIX 3, Plan 9 from Bell Labs, AmigaOS 4, MorphOS and FreeDOS.

The first personal computer operating system on a CD to support “live” operations might have been the AmigaOS, which could be booted from CD on an Amiga CDTV in 1990.. Earlier examples of live OS are of course the operating systems used from floppy, and most widely spread is DOS.

Unlike previous operating systems on optical media,

On a PC, a bootable Compact Disc generally conforms to the El Torito specification. Many Linux based live CDs use a compressed filesystem image, often with the cloop compressed loopback driver, or squashfs compressed filesystem, generally doubling effective storage capacity, although slowing application start up.

The resulting environment can be quite rich: typical Knoppix systems include around 1,200 separate software packages. Live CDs have a reputation for supporting advanced auto-configuration and plug-and-play functionality. This came out of necessity to avoid requiring the user to configure the system each time it boots and to make it easily usable by those who are new to the operating system.

Adapted from the Wikipedia article Live CD, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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The term ”reverse engineering” as applied to software means different things to different people, prompting Chikofsky and Cross to write a paper researching the various uses and defining a taxonomy. From their paper, they state, “Reverse engineering is the process of analyzing a subject system to create representations of the system at a higher level of abstraction.” It can also be seen as “going backwards through the development cycle”. In this model, the output of the implementation phase (in source code form) is reverse-engineered back to the analysis phase, in an inversion of the traditional waterfall model. Reverse engineering is a process of examination only: the software system under consideration is not modified (which would make it re-engineering). Software anti-tamper technology is used to deter both reverse engineering and re-engineering of proprietary software and software-powered systems. In practice, two main types of reverse engineering emerge. In the first case, source code is already available for the software, but higher-level aspects of the program, perhaps poorly documented or documented but no longer valid, are discovered. In the second case, there is no source code available for the software, and any efforts towards discovering one possible source code for the software are regarded as reverse engineering. This second usage of the term is the one most people are familiar with. Reverse engineering of software can make use of the clean room design technique to avoid copyright infringement.

On a related note, black box testing in software engineering has a lot in common with reverse engineering. The tester usually has the API, but their goals are to find bugs and undocumented features by bashing the product from outside.

Other purposes of reverse engineering include security auditing, removal of copy protection (“cracking”), circumvention of access restrictions often present in consumer electronics, customization of embedded systems (such as engine management systems), in-house repairs or retrofits, enabling of additional features on low-cost “crippled” hardware (such as some graphics card chip-sets), or even mere satisfaction of curiosity.

The Certified Reverse Engineering Analyst (CREA) is a certification provided by the IACRB that certifies candidates are proficient in reverse engineering software.

Binary software

This process is sometimes termed ”Reverse Code Engineering”, or RCE. As an example, decompilation of binaries for the Java platform can be accomplished using Jad. One famous case of reverse engineering was the first non-IBM implementation of the PC BIOS which launched the historic IBM PC compatible industry that has been the overwhelmingly dominant computer hardware platform for many years. An example of a group that reverse-engineers software for enjoyment is CORE which stands for “Challenge Of Reverse Engineering”. Reverse engineering of software is protected in the U.S. by the fair use exception in copyright law. The Samba software, which allows systems that are not running Microsoft Windows systems to share files with systems that are, is a classic example of software reverse engineering, since the Samba project had to reverse-engineer unpublished information about how Windows file sharing worked, so that non-Windows computers could emulate it. The Wine project does the same thing for the Windows API, and OpenOffice.org is one party doing this for the Microsoft Office file formats. The ReactOS project is even more ambitious in its goals, as it strives to provide binary (ABI and API) compatibility with the current Windows OSes of the NT branch, allowing software and drivers written for Windows to run on a clean-room reverse-engineered GPL free software or open-source counterpart.

Binary software techniques

Reverse engineering of software can be accomplished by various methods.

The three main groups of software reverse engineering are

#Analysis through observation of information exchange, most prevalent in protocol reverse engineering, which involves using bus analyzers and packet sniffers, for example, for accessing a computer bus or computer network connection and revealing the traffic data thereon. Bus or network behaviour can then be analyzed to produce a stand-alone implementation that mimics that behaviour. This is especially useful for reverse engineering device drivers. Sometimes, reverse engineering on embedded systems is greatly assisted by tools deliberately introduced by the manufacturer, such as JTAG ports or other debugging means. In Microsoft Windows, low-level debuggers such as SoftICE are popular.

#Disassembly using a disassembler, meaning the raw machine language of the program is read and understood in its own terms, only with the aid of machine-language mnemonics. This works on any computer program but can take quite some time, especially for someone not used to machine code. The Interactive Disassembler is a particularly popular tool.

#Decompilation using a decompiler, a process that tries, with varying results, to recreate the source code in some high-level language for a program only available in machine code or bytecode.

Adapted from the Wikipedia article Reverse engineering, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Real-time operating systems

A real-time operating system (RTOS) is a multitasking operating system intended for applications with fixed deadlines (real-time computing). Such applications include some small embedded systems, automobile engine controllers, industrial robots, spacecraft, industrial control, and some large-scale computing systems.

An early example of a large-scale real-time operating system was Transaction Processing Facility developed by American Airlines and IBM for the Sabre Airline Reservations System.

Embedded systems that have fixed deadlines use a real-time operating system such as VxWorks, eCos, QNX, MontaVista Linux and RTLinux. Windows CE is a real-time operating system that shares similar APIs to desktop Windows but shares none of desktop Windows’ codebase.

Some embedded systems use operating systems such as Symbian OS, Palm OS, BSD, and GNU/Linux, although such operating systems do not support real-time computing.

Hobby development

Operating system development is one of the more involved and technical options for the ”computing” hobbyist.

A hobby operating system is classified as one with little or no support from maintenance developers.

Development usually begins with an existing operating system.

The hobbyist is their own developer, or they interact in a relatively small and unstructured group of individuals who are all similarly situated with the same code base.

Examples of a hobby operating system include Syllable and ReactOS;

Minix is a classical example.

Ot

her

Older operating systems which are still used in niche markets include OS/2 from IBM and Microsoft; Mac OS, the non-Unix precursor to Apple’s Mac OS X; BeOS; XTS-300. Some, most notably AmigaOS 4 and RISC OS, continue to be developed as minority platforms for enthusiast communities and specialist applications. OpenVMS formerly from DEC, is still under active development by Hewlett-Packard.

There were a number of operating systems for 8 bit computers – Apple’s DOS (Disk Operating System) 3.2 & 3.3 for Apple II, ProDOS, UCSD, CP/M – available for various 8 and 16 bit environments, FutureOS for the Amstrad CPC6128 and 6128Plus.

Research and development of new operating systems continues. GNU Hurd is designed to be backwards compatible with Unix, but with enhanced functionality and a microkernel architecture. Singularity is a project at Microsoft Research to develop an operating system with better memory protection based on the .Net managed code model. Systems development follows the same model used by other Software development, which involves maintainers, version control “trees”, forks, “patches”, and specifications. From the AT&T-Berkeley lawsuit the new unencumbered systems were based on 4.4BSD which forked as FreeBSD and NetBSD efforts to replace missing code after the Unix wars. Recent forks include DragonFly BSD and Darwin from BSD Unix.

Adapted from the Wikipedia article Operating system/Draft, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Although Microsoft’s implementation of the Windows API is copyrighted, it is generally accepted due to legal precedents in the United States that other vendors can emulate Windows by providing an identical API (but not an identical implementation in code) without breaching copyright.

The Wine project is an attempt to provide a Win32 API compatibility layer for Unix-like platforms. ReactOS goes a step further and aims to provide an implementation of the entire Windows operating system, working closely with the Wine project to promote code re-use and compatibility. DosWin32 and HX DOS-Extender are other projects which emulate the Windows API allowing the execution of simple Windows programs from a DOS command line. Odin is a project to emulate Win32 on top of OS/2.

Adapted from the Wikipedia article Windows API, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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MS-DOS and Win32 console

FreeDOS is mostly compatible with MS-DOS. It supports .COM executables, standard DOS executables and Borland’s 16-bit DPMI executables. It is also possible to run 32-bit DPMI executables using DOS extenders. The operating system has several improvements relative to MS-DOS, mostly involving support of newer standards and technologies that did not exist when Microsoft ended support for MS-DOS, such as internationalization, Advanced Power Management TSRs, and integrated ASPI. Furthermore, with use of HX DOS Extender, many Win32 console applications function properly in FreeDOS, as do some GUI programs, like QEMU and Bochs.

Windows 1.0 to 3.xx

FreeDOS is able to run Microsoft Windows 1.0 and 2.0 releases. Windows 3.x releases, which had support for i386 processors, can be run in ”386 Enhanced Mode” since FreeDOS kernel build 2037.

Windows 9x and Windows Millennium Edition

Windows 95, 98 and Me use a stripped down version of MS-DOS as a bootloader. FreeDOS cannot be used as a replacement bootloader; however, it can be installed and used beside these systems using a boot manager program, such as the “METAKERN” included with FreeDOS. Problems running Windows result from Microsoft’s efforts to prevent their products running on non-Microsoft DOS implementations.

Windows NT/2000/XP/2003/Vista/2008/7/2008 R2 and ReactOS

Windows NT-based operating systems, including Windows 2000, XP, 2003, Vista, 2008, 7 and 2008 R2 do not make use of MS-DOS as a core component of the system. These sy

File systems

Adapted from the Wikipedia article FreeDOS, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Oracle VM VirtualBox is an x86 virtualization software package, originally created by German software company innotek GmbH, purchased by Sun Microsystems, and now developed by Oracle Corporation as part of its family of virtualization products. It is installed on an existing host operating system; within this application, additional guest operating systems, each known as a ”Guest OS”, can be loaded and run, each with its own virtual environment.

Supported host operating systems include Linux, Mac OS X, Windows XP, Windows Vista, Windows 7 and Solaris; there is also a port to FreeBSD (only OSE version). Supported guest operating systems include a small number of versions of NetBSD and various versions of DragonFlyBSD, FreeBSD, Linux, OpenBSD, OS/2 Warp, Windows, Solaris, Haiku, Syllable, ReactOS and SkyOS. Since release 3.2.0, VirtualBox also allows limited virtualization of Mac OS X guests on Apple hardware. Mac OS X cannot legally run on other hardware due to the Apple System Management Controller (SMC) in all Apple machines that performs a check to determine if Mac OS X is running on Apple hardware.

According to a 2007 survey by DesktopLinux.com, VirtualBox was the third most popular software package for running Windows programs on Linux desktops.

Adapted from the Wikipedia article VirtualBox, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Emulation allows the use of some Windows applications without using Microsoft Windows. These include:

*Wine — a free and open source software implementation of the Windows API, allowing one to run many Windows applications on x86-based platforms, including Linux and Mac OS X. Wine developers refer to it as a “compatibility layer”; and make use of Windows-style APIs to emulate the Windows environment.

**CrossOver — A Wine package with licensed fonts. Its developers are regular contributors to Wine, and focus on Wine running officially supported applications.

**Cedega — TransGaming Technologies’ proprietary fork of Wine, designed specifically for running games written for Microsoft Windows under Linux. A version of Cedega known as Cider is used by some video game publishers to allow Windows games to run on Mac OS X. Since wine was licensed under the LGPL Cedega has been unable to port the improvements made to wine to their proprietary codebase.

**Darwine — A bundling of Wine to the PowerPC Macs running OS X by running wine on top of QEMU. Intel Macs use the same Wine as other *NIX x86 systems.

*ReactOS — An open-source OS that is intended to run the same software as Windows, originally designed to simulate Windows NT 4.0, now aiming at Windows XP and Vista/7 compatibility. It has been in the development stage since 1996.

Adapted from the Wikipedia article Microsoft Windows, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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* BeOS kernel

** Haiku kernel

* Syllable

* BSD-based

** DragonFly BSD (first non-Mach BSD OS to use a hybrid kernel, concepts inspired by AmigaOS)

** XNU kernel (core of Darwin, used in Mac OS X)

* NetWare kernel

* Plan 9 kernel

** Inferno kernel

* NT kernel (used in Windows NT 3.1, Windows NT 3.5, Windows NT 4.0, Windows 2000, Windows Server 2003, Windows XP, Windows Vista, Windows Server 2008, Windows 7)

** ReactOS kernel

Adapted from the Wikipedia article Hybrid kernel, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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AbiWord is a free and open source software word processor. It was originally started by SourceGear Corporation as the first part of a proposed AbiSuite. Development stopped when SourceGear changed their focus to Internet appliances. AbiWord was adopted by some open source developers and AbiWord continued to be developed. The name “AbiWord” (pronounced “Abby Word”) is derived from the root of the Spanish word “”abierto””, meaning “open”. It runs on Linux, Microsoft Windows, ReactOS, Solaris, AmigaOS 4.0 (through its Cygnix X11 engine), and other operating systems. However, the Mac OS X port has been stuck in version 2.4 since 2005. AbiWord is part of GNOME Office, a collection of office applications with some degree of integration.

Adapted from the Wikipedia article AbiWord, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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