LearnSCADA 6502 Emulator

6502 Emulator Online

by Charles Vance

A free 6502 emulator that runs in your browser: a small 8-bit computer with a real 6502 processor and Microsoft BASIC 1.1 from 1978. It is for anyone who wants to learn 6502 BASIC and assembly language the way people first learned to program, from curious beginners and retro computing fans to students and technicians who want to see what a processor really does. Open it and start typing. There is nothing to install and no sign-up.

Type a line, press Return, and the computer answers. When you are ready to go deeper, the Machine Code Workbench assembles 6502 code and steps through it one instruction at a time.

It is the computer from the book Learn BASIC and Assembly on the 6502: every listing in the book runs on it exactly as printed.

Open the Emulator

Free for everyone. No account needed to start.

The LearnSCADA 6502 Emulator running a BASIC program, with the Machine Code Workbench beside the screen
The emulator, with the Machine Code Workbench open.

Save your programs

The emulator is free for everyone, with no account. A free LearnSCADA account (Free Reader) keeps the programs you write, so they are there next time: SAVE in BASIC, Save in the Workbench, and downloads from Files.

Join free to save your programs Sign in

The companion book

Learn BASIC and Assembly on the 6502 by Charles VanceComing soon

From your first PRINT to 6502 machine code and a working connection to a plant over Modbus, written for this emulator.

What you can do

Write BASIC programs

Microsoft BASIC 1.1 for the 6502, the same BASIC that shipped in the home computers of the late 1970s. With a free account, programs you SAVE are kept for next time.

Step through machine code

The Machine Code Workbench assembles 6502 code into memory. Step one instruction at a time, set breakpoints, and watch the registers, the stack and memory change.

Run a water plant over Modbus

The Fieldbus tab connects the computer to a simulated water treatment plant. Read its tank levels and pressures and switch its pumps from BASIC or machine code, over Modbus TCP.

Quick start

  1. Press Start the Computer.
  2. Type PRINT "HELLO" and press Return.
  3. Try a program:10 PRINT "HELLO" 20 GOTO 10 RUNPress Esc to STOP it, and type LIST to see it again.
  4. Reset restarts the computer. Anything not saved is lost.
  5. Files uploads programs from your computer. With a free account it also keeps your saved programs and downloads them.

For a desktop or laptop with a keyboard. It is not made for phones or tablets.

LearnSCADA 6502 BASIC Emulator. Includes Microsoft BASIC for 6502, Version 1.1, Copyright (c) Microsoft Corporation, MIT License.