Bochs (pronounced "box") is a portable

IA-32 IA-32 (short for "Intel Architecture, 32-bit", commonly called ''i386'') is the 32-bit version of the x86 instruction set architecture, designed by Intel and first implemented in the i386, 80386 microprocessor in 1985. IA-32 is the first incarn ...

and

x86-64 x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit extension of the x86 instruction set architecture, instruction set. It was announced in 1999 and first available in the AMD Opteron family in 2003. It introduces two new ope ...

IBM PC compatible An IBM PC compatible is any personal computer that is hardware- and software-compatible with the IBM Personal Computer (IBM PC) and its subsequent models. Like the original IBM PC, an IBM PC–compatible computer uses an x86-based central p ...

emulator In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run sof ...

and

debugger A debugger is a computer program used to test and debug other programs (the "target" programs). Common features of debuggers include the ability to run or halt the target program using breakpoints, step through code line by line, and display ...

mostly written in C++ and distributed as

free software Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...

under the

GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

. It supports emulation of the processor(s) (including

protected mode In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as Memory_segmentation, segmentation, virtual mem ...

), memory, disks, display,

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...

and common hardware peripherals of PCs. Many guest

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

s can be run using the emulator including DOS, several versions of

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, pac ...

Xenix Xenix is a discontinued Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation. The first version was released in 1980, and Xenix was the most common Unix variant during the mid- to late-1980s. T ...

Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

BSD The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginni ...

s and Rhapsody OS ( precursor of

Mac OS X Public Beta Mac OS X Public Beta (internally code named "Kodiak") was the first publicly available version of Apple Inc., Apple Computer's macOS, Mac OS X (now named macOS) operating system to feature the Aqua (user interface), Aqua user interface. It was ...

). Bochs runs on many host operating systems, including Android OS,

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

PlayStation 2 The PlayStation 2 (PS2) is a home video game console developed and marketed by Sony Interactive Entertainment, Sony Computer Entertainment. It was first released in Japan on 4 March 2000, in North America on 26 October, in Europe on 24 Novembe ...

Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

, and

Windows CE Windows CE, later known as Windows Embedded CE and Windows Embedded Compact, is a discontinued operating system developed by Microsoft for mobile and embedded devices. It was part of the Windows Embedded family and served as the software foun ...

along with its derivatives. Bochs is mostly used for operating system development (when an emulated operating system crashes, it does not crash the host operating system, so the emulated OS can be debugged) and to run other guest operating systems inside already running host operating systems. It can also be used to run older software — such as PC games — which will not run on non-compatible, or too fast computers.

History

Bochs started as a program with a commercial license, at the price of

US$ The United States dollar (Currency symbol, symbol: Dollar sign, $; ISO 4217, currency code: USD) is the official currency of the United States and International use of the U.S. dollar, several other countries. The Coinage Act of 1792 introdu ...

25, for use as-is. If a user needed to link it to other software, that user would have to negotiate a special license. That changed on 22 March 2000, when Mandrakesoft (later

Mandriva Mandriva S.A. was a Public company, public software company specializing in Linux and open-source software. Its corporate headquarters was in Paris, and it had development centers in Metz, France and Curitiba, Brazil. Mandriva, S.A. was the deve ...

) bought Bochs from lead developer Kevin Lawton and released it for

under the

. Support for hosting on

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct successor to Windows 2000 for high-end and business users a ...

ended with version 2.6.10.

Use

Bochs emulates the hardware needed by PC operating systems, including hard drives, CD drives, and floppy drives. It doesn't utilize any host CPU

virtualization In computing, virtualization (abbreviated v12n) is a series of technologies that allows dividing of physical computing resources into a series of virtual machines, operating systems, processes or containers. Virtualization began in the 1960s wit ...

features, therefore is slower than most virtualization (as opposed to emulation) software. It provides additional security by completely isolating the guest OS from the hardware. Bochs also has extensive debugging features. It is widely used for OS development, as it removes the need for constant system restarts (to test code). BFE, described as a "Graphical Debugger Interface for the Bochs PC Emulator", is a graphical interface for the debugger within the Bochs PC emulator that makes it possible to debug software step-by-step at the instruction and register level, much like Borland's

Turbo Debugger Turbo Debugger (TD) is a machine-level debugger for DOS executables, intended mainly for debugging Borland Turbo Pascal, and later Turbo C programs, sold by Borland. It is a full-screen debugger displaying both Turbo Pascal or Turbo C source and ...

Emulated hardware

References

{{Virtualization products 1994 software Cross-platform software Formerly proprietary software Free emulation software Free software programmed in C++ Linux emulation software MacOS emulation software Pocket PC software Windows emulation software X86 emulators Software using the GNU Lesser General Public License