X86Emulator

Another x86 emulator which is like bochs. But it is much weaker in the functionality. As it is a course project,now we only want to emulate MS-DOS on it. Some features

• It supports bochs like debugging. For example,set break points,show registers,disasm instructions.
• It supports Windows,Linux and other platforms that Qt4.x can work. Qt is used as a GUI toolkit in the project. And the core part of the code can work on any platform that supports c++ and does arithmetic calculation with 2's complement.
• It supports almost all basic instructions and system instrutions in the one byte opcode table in the 16bit,32bit and 64bit mode. As 32bit protect-mode and 64bit long-mode is real complicated,we didn't implement it. So it can only emulate the real mode programs like MS-DOS.
• We emulate the BIOS intermediate layer which DOS relays on,so there is no real hardware emulation. So it takes much lesser time to code. And this is a very important difference between X86Emulator and bochs.

How to build it

Some requirements

• Qt 4.x or 5.x
• nasm(may not be necessary)

Steps

1. cd into the src/bios/ and execute the genBin.sh(unix) or genBin.cmd(windows).As I have upload one bios.bin, this may not be necessary.
2. cd into the src/ ,use qmake to generate the native makefile,then make it.Using Qt Creater to open the X86Emulator.pro and Compiling it is another but actually the same way.
3. Finally,you will find a X86Emulator executable file in the X86Emulator directory.

The End

As a course project, its life ended after a demo in the course projcet presentation.The project is partially succeeded.It do run MS-DOS 6.22 now,but not all commands and programs in DOS works well. ###Screenshots The followings are some screenshots.

DOS start up screen.

The most successful one.

The Next one is the screenshot of the X86Emulator debugger which is very similar to bochs's.

The last one is a failed case,EDIT.EXE in DOS.

So there are still some bugs in the code or hardware emulation is not enough for Edit.EXE.

###Acknowledgement Bochs is a nice x86 emulator,without which I would not start up this project and end this project.
EasyVM is a nice implementation reference,as it is small and easy enough to understand.Many thanks to its author,Yixin Liang,who open source it.

Further

If you want to do some course projects like x86 emulator,assembler,disassembler,executer,analyser etc.This is a good reference. The following is a design of the CPU Instruction Processing Pipeline. As I have taken future extension into consideration during the design,it is not hard to use this code to make a x86 disassembler etc.And the whole design is in the wiki pages,but mainly in chinese.