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Online 6502 Assembler Simulator

As explained in Classic Game Programming on the NES: Make your own retro video game

The Online 6502 Assembler Simulator is a browser-based tool that assembles and executes 6502 assembly code while exposing processor registers and memory for inspection.

The Online 6502 Assembler Simulator is a browser-based workspace for typing or pasting 6502 assembly, assembling it, running it, and inspecting the result. Its interface separates the assembly code area, debugger, screen output, and assembler output windows. section 3.1

Use the simulator in this order:

  • Click Reset, enter or paste assembly code, and click Assemble. section 3.1
  • If assembly produces no errors, click Run to execute the code. section 3.1
  • Read final register values in the debugger. section 3.1
  • Select Monitor to display memory contents in 256-byte sections. section 3.1

Verify register storage

Paste `lda #$10`, `sta $06`, `ldx #$11`, `stx $07`, and `ldy #$12`, `sty $08`. Assemble, enable Monitor, and run. The debugger should show A=$10, X=$11, and Y=$12; zero-page memory should show $10, $11, and $12 at locations $06–$08. section 3.3.2

Figure 3.1 Access the Online 6502 Assembler Simulator.

Open the simulator access figure to identify the workspace before entering code. section 3.1

How Classic Game Programming on the NES: Make your own retro video game covers it

How deep it goes
Explains operation through reset, assembly, execution, register inspection, and memory monitoring, without detailing assembler internals.
Examples
Demonstrates immediate loads, zero-page stores, absolute stores, and indexed stores with debugger and memory output.
What you can do after
Operate/configure the simulator to run 6502 code and verify register or memory changes.
How it connects
Connects 6502 assembly to registers, memory, zero-page storage, and addressing modes.

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Classic Game Programming on the NES: Make your own retro video game. The section links point to the parts of the book it draws on.