Bochs
Encyclopedia
Bochs is a portable x86 and x86-64
IBM PC compatible
emulator
and debugger
mostly written in C++
and distributed as free software
under GNU Lesser General Public License
. It supports emulation of the processor(s) (including protected mode
), memory, disks, display, Ethernet
, BIOS
and common hardware peripherals of PCs
.
Many guest operating system
s can be run using the emulator including DOS
, several versions of Microsoft Windows
, BSDs, Linux
, Xenix
and Rhapsody (precursor of Mac OS X). Bochs can run on many host operating systems, like Windows
, Windows Mobile
, Linux
, Mac OS X
and iOS.
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.
It uses SeaBIOS
.
, 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 (now Mandriva
) bought Bochs from lead-developer Kevin Lawton and released it for Linux
under the GNU Lesser General Public License
.
software. Bochs is widely used for hobbyist OS developing, as it saves the need for constant system restarts (to test code). Bochs is also convenient for OS developers because it has error reporting and dump files that other emulators may lack.
BFE makes it possible to debug software step-by-step at the instruction and register level, much like Borland's Turbo Debugger.
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...
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...
emulator
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
and debugger
Debugger
A debugger or debugging tool is a computer program that is used to test and debug other programs . The code to be examined might alternatively be running on an instruction set simulator , a technique that allows great power in its ability to halt when specific conditions are encountered but which...
mostly written in C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
and distributed as free software
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
under GNU Lesser General Public License
GNU Lesser General Public License
The GNU Lesser General Public License or LGPL is a free software license published by the Free Software Foundation . It was designed as a compromise between the strong-copyleft GNU General Public License or GPL and permissive licenses such as the BSD licenses and the MIT License...
. It supports emulation of the processor(s) (including protected mode
Protected mode
In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units...
), memory, disks, display, Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
, BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
and common hardware peripherals of PCs
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...
.
Many guest operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s can be run using the emulator including 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...
, several versions of Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
, BSDs, 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...
, Xenix
Xenix
Xenix is a version of the Unix operating system, licensed to Microsoft from AT&T in the late 1970s. The Santa Cruz Operation later acquired exclusive rights to the software, and eventually superseded it with SCO UNIX ....
and Rhapsody (precursor of Mac OS X). Bochs can run on many host operating systems, like Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
, Windows Mobile
Windows Mobile
Windows Mobile is a mobile operating system developed by Microsoft that was used in smartphones and Pocket PCs, but by 2011 was rarely supplied on new phones. The last version is "Windows Mobile 6.5.5"; it is superseded by Windows Phone, which does not run Windows Mobile software.Windows Mobile is...
, 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...
, Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
and iOS.
Bochs is mostly used for operating system development (when an emulated operating system crashes
Crash (computing)
A crash in computing is a condition where a computer or a program, either an application or part of the operating system, ceases to function properly, often exiting after encountering errors. Often the offending program may appear to freeze or hang until a crash reporting service documents...
, it does not crash the host operating system, so the emulated OS can be debugged
Debugging
Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware, thus making it behave as expected. Debugging tends to be harder when various subsystems are tightly coupled, as changes in one may cause bugs to emerge...
) 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.
It uses SeaBIOS
SeaBIOS
SeaBIOS is an open source implementation of a 16-bit x86 BIOS. SeaBIOS can run in an emulator or it can run natively on x86 hardware with the use of coreboot....
.
History
Bochs started as a program with a commercial license, at the price of 25 USDUnited States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
, 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 (now Mandriva
Mandriva
Mandriva S.A. is a publicly traded Linux and open source software company with its headquarters in Paris, France and development center in Curitiba, Brazil. Mandriva, S.A...
) bought Bochs from lead-developer Kevin Lawton and released it for 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...
under the GNU Lesser General Public License
GNU Lesser General Public License
The GNU Lesser General Public License or LGPL is a free software license published by the Free Software Foundation . It was designed as a compromise between the strong-copyleft GNU General Public License or GPL and permissive licenses such as the BSD licenses and the MIT License...
.
Use
Bochs can emulate the hardware needed by the guest operating system, including hard drives, CD drives, and floppy drives. Disk and ISO images can be "inserted" while the system is being run. However, the system performance is very slow because it is only emulated. It doesn't provide any CPU virtualization features. However, it is useful for capturing screen shots in researching old DOSDOS
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...
software. Bochs is widely used for hobbyist OS developing, as it saves the need for constant system restarts (to test code). Bochs is also convenient for OS developers because it has error reporting and dump files that other emulators may lack.
BFE makes it possible to debug software step-by-step at the instruction and register level, much like Borland's Turbo Debugger.
Emulated hardware
| Class | Device |
|---|---|
| Video card Video card A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors... |
Cirrus Logic CL-GD5430 ISA Industry Standard Architecture Industry Standard Architecture is a computer bus standard for IBM PC compatible computers introduced with the IBM Personal Computer to support its Intel 8088 microprocessor's 8-bit external data bus and extended to 16 bits for the IBM Personal Computer/AT's Intel 80286 processor... |
| Cirrus Logic CL-GD5446 PCI | |
| Sound card Sound card A sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware... |
Sound Blaster 16 Sound Blaster 16 The Sound Blaster 16 is a series of sound cards by Creative Technology. They are add-on boards for PCs with an ISA or PCI slot.-Sound Blaster 16:Sound Blaster 16 , the successor to the Sound Blaster Pro, introduced 16-bit digital audio sampling to the Sound Blaster line... card (ISA, no Plug & Play) |
| NE2000 NE2000 The NE1000/NE2000 is an early line of low cost Ethernet network cards originally produced by Novell. Its popularity had a significant impact on the pervasiveness of networks in computing... Ethernet Ethernet Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies.... |
|
| Chipset Chipset A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :... |
Intel 440FX Intel 440FX The Intel 440FX , is a chipset from Intel, supporting the Pentium Pro and Pentium II processors. It is the first chipset from Intel that supports Pentium II. It is also known as i440FX and was released in May 1996. Official part numbers include the 82441FX and the 82442FX.440FX does not support... PCI. Host-to-PCI bridge (PMC/DBX), PCI-to-ISA bridge, PCI IDE controller (PIIX3) are available. For PCI cards there are 5 PCI slots. |
| USB Universal Serial Bus USB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices.... |
Root hub and the devices mouse, tablet, keypad, disk. |
| SMP Symmetric multiprocessing In computing, symmetric multiprocessing involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance. Most common multiprocessor systems today use an SMP architecture... |
Can simulate up to 8 CPUs. |
| Enhanced BIOS | ElTorito El Torito (CD-ROM standard) The El Torito Bootable CD Specification is an extension to the ISO 9660 CD-ROM specification. It is designed to allow a computer to boot from a CD-ROM... , EDD INT 13 INT 13H or INT 19 is shorthand for BIOS interrupt call 13hex, the 20th interrupt vector in an x86-based computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and floppy disk read and write services using cylinder-head-sector ... v3.0, basic APM Advanced Power Management Advanced power management is an API developed by Intel and Microsoft and released in 1992 which enables an operating system running an IBM-compatible personal computer to work with the BIOS to achieve power management.Revision 1.2 was the last version of the APM specification, released in 1996.... , PCIBIOS features, PCI interrupt routing table. 32-bit init for ACPI Advanced Configuration and Power Interface In computing, the Advanced Configuration and Power Interface specification provides an open standard for device configuration and power management by the operating system.... , SMM System Management Mode System Management Mode is an operating mode in which all normal execution is suspended, and special separate software is executed in high-privilege mode. It was first released with the Intel 386SL... and SMP Symmetric multiprocessing In computing, symmetric multiprocessing involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance. Most common multiprocessor systems today use an SMP architecture... . |