A toy 8-bit machine emulated in JavaScript. Implements most of the 6502 instruction set plus some extras for convenience and debugging. (I created this as a way to learn 6502 as I was learning to program my Commodore 64.) Has a small kernal written in assembly to output characters to the screen, blink the cursor (using interrupts), and echo keyboard input to the screen.
See the prg/ folder for test programs and the kernal code (kernal.s). To run any of these change the fileName in the loadKernal() method in parser.js.
A primitive parser (parser.js) converts the assembly to machine code which is executed in cpu.js.
The instruction set is defined in instruction-set.js.
A memory map can be found in the console when running and also in memory-map.js.
The character set is defined in chars.js.
Uses PixiJS for rendering all the pixels.
https://rscottfree.github.io/machine-assembly-code-learning-environment/
Clone
npm install
npm start
Go to http://localhost:8080
- The Commodore 64 & The Programmer's Reference Guide
- Jim Butterfield's book Machine Language for the Commodore 64
- Robin at 8-Bit Show and Tell
Instructions
- https://www.masswerk.at/6502/6502_instruction_set.html
- https://dwheeler.com/6502/oneelkruns/asm1step.html
Stack and interrupts
- https://wiki.nesdev.com/w/index.php/Stack
- https://www.c64-wiki.com/wiki/Interrupt
- https://dustlayer.com/c64-coding-tutorials/2013/4/8/episode-2-3-did-i-interrupt-you
Interrupts