A JavaScript assembly x86 compiler + emulator for educational purposes
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Asm86.js Fixed invalid number bug Dec 3, 2016
Asm86Language.js Updated the license Oct 10, 2013
LICENSE.txt Create LICENSE.txt Oct 10, 2013
README.md Update README.md Oct 10, 2013

README.md

Asm86

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

The project site, http://carlosrafaelgn.com.br/Asm86, can be used as an example (in English). It uses CodeMirror (http://codemirror.net) as the code editor.

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.