Visual Assembler - Commodore 64

C64 Visual Assembler is a desktop application that lets you write Commodore 64 machine code programs visually — no text editor required.

Instead of typing assembly by hand, you drag instruction blocks from a palette, arrange them in order, and the app compiles everything in real time. It's perfect for learning 6502 assembly or quickly prototyping C64 programs.

  ✨ Features:

• Block-based editor — drag & drop 6502 mnemonics onto the program canvas 
• Real-time compilation — see the assembled bytes instantly as you build
• ASM view — clean, readable assembly output with labels and comments
• Monitor view — raw hex dump like a real C64 monitor (>0801  A9 00 8D 20 D0…)
• Memory map — visual overview of your program in C64 address space
• KERNAL autocomplete — built-in list of C64 KERNAL routines for JSR/JMP
• Sample programs — text scroller, sprite demo, border color effects and more
• VICE integration — launch your program directly in the VICE emulator
• Light & dark theme, English & Hungarian UI
• Save & load projects as JSON

  🖥️ System requirements:

• Windows 10/11 (64-bit)
• Optional: VICE emulator for running programs

  👤 Author:

  © 2026 Zsolt Tarczali — made with ❤️ for the C64 community — zstarczali

Mac OSX Troubleshooting:

"App is damaged" error:

1. Go to System Settings → Privacy & Security
2. Scroll down and click "Open Anyway" next to the blocked app message OR run in Terminal:
3. xattr -cr "/Applications/C64 Visual Assembler.app"

Requirements: macOS 11.0+, Apple Silicon (M1/M2/M3/M4)

What's New v1.0.4

• RAWBYTES — new macro: place raw bytes directly at a given memory address without generating any LDA/STA code. A deferred .byte section appears in the ASM view.
• RAWTEXT — new macro: place text as PETSCII bytes at a given memory address without generating any LDA/STA code. Useful for defining character sets and screen data.
• Some bug fixes.

What's New v1.0.5

• Illegal opcodes — new category with 12 stable 6502 illegal instructions: LAX, SAX, DCP, ISC, SLO, RLA, SRE, RRA, ANC, ALR, ARR, AXS. Displayed with a red tone in the palette.
• HEX/DEC toggle for byte macros — BYTE, DATA and RAWBYTES blocks now show a HEX/DEC toggle. In HEX mode values can be entered as e.g. FF,00,8D; switching automatically converts existing values.

What's New v1.0.9

• Hello World 1–40 demo — new sample program: uses LOOP / NEXT macro to print "Hello World X" 40 times, where X is the current counter (1 to 40). ASCII digit counter on zero page ($FB / $FC) with automatic two-digit handling.

• LOOP / NEXT macro — new visual loop block pair. LOOP sets up the counter (X or Y register, hex value), NEXT auto-connects and generates DEX/DEY + BNE. Nested loops are fully supported.

• Bitmap line demo — new sample program: draws 8 straight lines in C64 hires bitmap mode, pixel data pre-computed in JavaScript using Bresenham's algorithm. LOOP / NEXT demo — new sample program: nested delay loops cycle the border and background through all 16 C64 colours slowly.