tearitco/asm86

A JavaScript assembly x86 compiler + emulator for educational purposes

Asm86

This is a JavaScript assembly x86 compiler and emulator for educational purposes. I use it in my classes on Computer Architecture.

The project sites carlosrafaelgn.github.io/Asm86 and carlosrafaelgn.com.br/Asm86 can be used as examples of how to use this library. They use CodeMirror as the code editor, licensed under the MIT License.

The script adds only three names to the global namespace: Asm86EmulatorContext, Asm86EmulatorCompiler and Asm86Emulator. However, creating instances of Asm86EmulatorContext and Asm86EmulatorCompiler will not be so usefull.

Asm86Language.js adds translation support and consumes two more names from the global namespace: Asm86Language and Asm86UI. Although the example is in English, the script's default language is Portuguese.

Limitations:

• Not all instructions have been implemented
• Not all flags have been implemented
• No segment/paging support
• Only 9 registers available (debug and control registers are not available)
• No task support as nowadays OSes implement (simple tasks can still be created using time-sharing algorithms)
• IO ports do not reflect the standard IO ports available in PC's
• No float point/MMX/SSE... instructions
• No advanced features like GDT, LDT
• IDT support is limited and does not reflect the original IDT description
• Instructions XSAVE and XRSTOR were changed and do not reflect the documented version
• Interrupts < 32, except for int 3, are not supported
• No instructions modifiers/prefixes, other than REP, have been implemented
• No 3 or more operands instructions have been implemented
• Not all CMOVcc/Jcc/SETcc instructions have been implemented
• Neither protected mode nor virtual mode has been implemented

I tried to be as faithful as possible to the manuals from Intel (although Volumes 2C, 3A, 3B and 3C were not too much used):

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume 1 - Basic Architecture (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-1-manual.html

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume Volume 2A: Instruction Set Reference, A-M (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2a-manual.html

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume Volume 2B: Instruction Set Reference, N-Z (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2b-manual.html

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume Volume 2C: Instruction Set Reference (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2c-manual.html

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume Volume 3A: System Programming Guide, Part 1 (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-3a-part-1-manual.html

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume Volume 3B: System Programming Guide, Part 2 (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-3b-part-2-manual.html

Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume Volume 3C: System Programming Guide, Part 3 (June 2013) http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-3c-part-3-manual.html

This projected is licensed under the terms of the FreeBSD License. See LICENSE.txt for more details.