6502 Assembler & Emulator written in JavaScript

Live Demo

6502 Emulator and Assembler written in JavaScript by Felipe Alfonso.

About the Emulator

The emulator has:

• 64 KB of memory.
• Screen memory starts at $0100 and ends at $04FF.
• Background color is defined at address $E400.
• Text color is defined at address $E401.
• Color values go from $0 to $F.

About the assembler

The assembler has:

• Basic assembly directives like .BYTE to define 8 bit values and .WORD to define 16 bit.
• Support for string use in .BYTE directive and char as immediate address mode.
• Multiple arguments for directives to define arrays.
• 6502 mnemonics.
• Labeling.
• Can set origin.

Note

• There might still be some issues with the assembler.
• Decimal mode not implemented yet
• No support for illegal opcodes. They will be transfromed to NOP by assembler.