Visual Assembler - Commodore 64 & C64U

Build real Commodore 64 machine code visually.

Visual Assembler is a desktop app that lets you learn and create C64 programs with a drag-and-drop, block-based editor instead of typing assembly by hand. It generates 6502 assembly and machine code in real time, making retro development faster, more visual, and easier to learn.

Perfect for beginners, retro enthusiasts, and C64 developers who want a faster way to prototype ideas, explore memory layout, and experiment with low-level code.

Visual Assembler brings modern visual workflow to classic Commodore 64 development.

If you’ve always wanted to create C64 assembly programs but didn’t want to start with a plain text editor, this is a fun and practical way to jump in.

Why it stands out

• Visual block editor for 6502 code
• Live ASM + monitor output while you build
• Memory map and origin control for real C64-style development
• VICE integration for one-click testing
• English, Spanish, German and Hungarian UI, with light/dark themes

Key features

• Drag & drop instruction and macro blocks onto a program canvas
• Real-time compilation with instant byte output
• Readable ASM view with labels and comments
• Classic C64 monitor-style hex dump view
• Built-in KERNAL routine support for faster JSR / JMP workflow
• Save/load projects as JSON, export PRG, run directly in VICE
• Commodore 64 Ultimate support.

Powerful macro system

Go beyond basic opcodes with advanced visual macros such as TEXT, STRING, DATA, BYTE, WORD, FILL, ALIGN, RAWBYTES, RAWTEXT, PETSCII, CHARSET, INCBIN, SID, INCLUDE, TABLE, ORG, LABEL, COMMENT, LOOP/NEXT, FOR/ENDF, PUSH/PULL, END, MACRO/ENDM/INVOKE, REGION/ENDREGION, DEFINE/IF/ELSE/ENDIF, CONST, VAR, IF_A/X/Y, WHILE_A/X/Y, REPEAT/UNTIL_A/X/Y, ENDW, MEMCPY, MEMSET, PRINT, PRINT_CHAR, PRINT_HEX, CLEAR_SCREEN, WAIT_KEY, DELAY/WAIT, SET_BORDER, SET_BG, IRQ_SETUP, RAND, SPRITE_INIT, SPRITE_POS, WAIT_RASTER, JOYSTICK, MOUSE, SPRITE_COL, LOADFILE, EXODECRUNCH, REU_CHECK, REU_STASH, REU_FETCH, REU_SWAP, TURBO_SET, SUPERCPU_DETECT, TURBO_ENABLE, MAP_COPY, SPRITE_ANIM, and SCORE_BCD.

Made for real C64 work

• Supports standard addressing modes and classic 6502 workflow
• Includes 12 stable illegal opcodes for advanced users
• Supports BASIC SYS stub on/off and alternative load addresses
• Lets you place raw data, text, sprites, music, and tables exactly where you need them

Extra touches

• CRT retro mode with scanlines, vignette, flicker, and barrel distortion
• Clickable ASM lines highlight the matching block in the editor
• Built-in samples and Knowledge Base links for learning faster

Platform support

• Windows 10 / 11 (x64, ARM)
• macOS 14+ on Apple Silicon (x64, Apple Silicon)
• Linux (x64)

Author

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

I made for:   

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)