Bochs – a highly portable open source IA-32 (x86) PC emulator written in C++, that runs on most popular platforms. It includes emulation of the Intel x86 CPU, common I/O devices, and a custom BIOS. Bochs can be compiled to emulate many different x86 CPUs, from early 386 to the most recent x86-64 Intel and AMD processors which may even not reached the market yet.
Bochs is written in the C++ programming language, and is designed to run on many different host platforms, including x86, PPC, Alpha, Sun, and MIPS. No matter what the host platform is, Bochs still simulates x86 hardware. In other words, it does not depend on the native instructions of the host machine at all. This is both a strength and a weakness, and it’s the major difference between Bochs and many other x86 emulation software such as VirtualBox, VMware, etc. Because Bochs uses software simulation for every single x86 instruction, it can simulate a Windows application on an Alpha or Sun workstation. However, the downside of Bochs’ approach is simulation performance. To model the processor accurately, Bochs must run many instructions for every simulated x86 instruction, and this makes the simulated machine many times slower than the physical machine. Commercial PC emulators (VMware, Connectix, etc.) can achieve much high emulation speed using a technique called virtualization, but they are neither portable to non-x86 platforms nor open source.
Bochs was written by Kevin Lawton starting in 1994. It started as a program with a commercial license, at the price of 25 USD, for use as-is. If a user needed to link it to other software, that user would have to negotiate a special license. Finally, in March 2000, MandrakeSoft (2005 to 2015 called Mandriva) bought Bochs and made it open source under the GNU LGPL. In March 2001, Kevin helped a few developers to move all Bochs activities from bochs.com to a new site.