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https://github.com/siravan/moonjs
A port of the Apollo Guidance Computer (AGC) simulator to javascript using the Emscripten compiler
https://github.com/siravan/moonjs
Last synced: 3 months ago
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A port of the Apollo Guidance Computer (AGC) simulator to javascript using the Emscripten compiler
- Host: GitHub
- URL: https://github.com/siravan/moonjs
- Owner: siravan
- License: gpl-2.0
- Created: 2013-11-03T13:27:54.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2013-11-08T03:41:40.000Z (over 11 years ago)
- Last Synced: 2023-08-05T10:52:18.428Z (over 1 year ago)
- Language: C
- Homepage: http://svtsim.com/moonjs/agc.html
- Size: 324 KB
- Stars: 54
- Watchers: 3
- Forks: 10
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- AwesomeCompiler - moonjs
README
Moonjs
======
Moonjs (http://svtsim.com/moonjs/agc.html) is an online Apollo Guidance
Computer (AGC) simulator. It is a port of the Virtual AGC
(http://www.ibiblio.org/apollo/) by Ronald Burkey from C to javascript
asm.js using the Emscripten compiler
(https://github.com/kripken/emscripten/wiki).
AGC was the main computer system of the Apollo program that successfully
landed 12 astronauts on Moon. There was one AGC on each of the Apollo
Command Modules and another one on each Lunar Module. There was also a
second backup computer system called Abort Guidance System (AGS) on the
Lunar Modules, which is simulated by Virtual AGC, but not the current
version of Moonjs.
Astronauts interacted with AGC by using DSKY, a combination of 7-segment
numerical displays, indicator lights and a simple keypad, which is
simulated on this page. The simulated DSKY communicates with a simulated
AGC, which in turn runs a copy of Colossus 249, the flight software
that flew on the Apollo 9 Command Module.
Why Javascript?
===============
Recent advances in the javascript language - such as optimized engines,
ahead-of-time (AOT) compilation, and asm.js - make it possible to write
computationally extensive applications in javascript.
My previous experience with online javascript-based simulation -
svtsim(svtsimcom/svtsim.html) and hemosim (svtsim.com/hemosim.html) -
was very positive and convinced me of the suitablity of the HTML5 and
javascript combination in writing portable, easy-to-use simulators.
Moonjs is the logical next step that uses Emscripten compiler
to convert existing C code into asm.js, a highly-optimizable subset
of javascript.
Compiling
=========
To build Moonjs, you need to have Emscripten and its requirements
(including Clang C compiler, python 2.7 and node.js) installed on your
computer.
Change the including Makefile by setting EMCC to the directory of the
installed Emscripten (default is /usr/local/emsripten). Compile the
source by
$ make
Do not use '.configure'. If compilation succeeds, it will generate
'agc.js' file which included the compiled asm.js and the required
libraries. It also generate 'agc.data', which is a copy of the corerope
image (provided as Core.bin) packaged for loading using AJAX.
Running
=======
The following files are needed to run Moonjs:
agc.html the main html page and the javascript code simulating DSKY
agc.js the compiled agc engine code
agc.data a copy of the Core.bin which is loaded by agc.js
during initialization
digital-7-mono-italic.ttf font file for seven-segment displays
Apollo_DSKY_interface.svg.png static graphic showing the DSKY interface
(public domain image from NASA)
Also if you are testing the software from local disk, Chrome security prevents
loading agc.data using AJAX over the local file system. If you are using Chrome,
you need to run a static web server. For example, run the following command
in the Moonjs directory:
$ python -m SimpleHTTPServer 8000
and run Moonjs by pointing the browser to http://localhost:8000/agc.html.