A JavaScript 6502 assembler and simulator which runs in a web browser, forked from: https://github.com/skilldrick/6502js
Enhancements include a speed control (slider), load/save buttons, an 80x25 character memory-mapped terminal screen, and some basic ROM routines.
A hosted copy is available at http://6502.cdot.systems - Click the "Notes" button and scroll through the text box at the bottom of the display for basic documentation, including links to some sample code. Some sample code to run within the emulator is available at https://github.com/ctyler/6502js-code
This version contains experimental syntax highlighting utilizing Code Bedder (https://codebedder.com/) and Prism.js (https://prismjs.com/).
The 6502js assembler and simulator is distributed under the terms of the GPL version 3; see the LICENSE file. The code-bedder (https://codebedder.com) code is licensed freely ("This library is free to use however you like."). The Prism.js library is distributed under the MIT license (see the LICENSE.prism file).