C64UHEX — Commodore 64 Ultimate Hex Editor

CODE NOT READY! This is for demonstration purposes ONLY -- Currently developing an Assembly/C hybrid version. The C64U has proven to be more challenging than expected to program.

C64UHEX is a native hex editor for the Commodore 64, designed to run on real hardware, the Commodore 64 Ultimate, and emulators such as VICE. It provides professional, byte-level inspection and modification of binary data using a true PETSCII interface, respecting the constraints and character semantics of the original platform.

This project is focused on correctness, stability, and historical authenticity, not modern abstractions.

🎯 Purpose & Scope

C64UHEX exists to fill a long-standing gap on the Commodore 64 platform: a real, usable hex editor comparable in workflow (not scale) to modern tools such as Hex Editor Neo, adapted for a 40×25 PETSCII display and 8-bit memory model.

It is intended for:

Binary inspection and modification
Reverse-engineering and analysis
Educational exploration of low-level data
Preservation and tooling for vintage computing

✅ What C64UHEX IS

A true hex editor, not a memory monitor
Overwrite-mode byte editor (hex-authoritative)
PETSCII-native character view (not ASCII emulation)
Paged buffer design supporting files larger than RAM
IEC device-agnostic (devices 8–15)
Designed for real C64 hardware
Written in C using the cc65 / cl65 toolchain
Distributed as a .PRG executable

❌ What C64UHEX IS NOT

❌ Not a BASIC program
❌ Not an ASCII editor
❌ Not a modern filesystem browser
❌ Not a debugger or disassembler
❌ Not a GUI application in the modern sense
❌ Not designed for speed over correctness
❌ Not a replacement for modern hex editors

C64UHEX deliberately avoids features that would compromise determinism, authenticity, or hardware compatibility.

✨ Core Features

Hex Data Grid
- 8 bytes per row
- Nibble-level cursor editing
PETSCII Interpretation Pane
- Accurate rendering of Commodore character codes
Paged ViewBuffer
- 160-byte window cache (20×8)
- Supports large files via on-demand paging
Cursor-centric Navigation
- Arrow-key movement
- Goto offset
Find
- Hex or PETSCII search modes
Device-Independent File I/O
- IEC devices 8–15
Runs on Real Hardware
- Tested on Commodore 64 Ultimate and VICE

🛠 Build Instructions (Host System)

C64UHEX is developed on a modern system and cross-compiled.

Requirements

cc65 toolchain
GNU make
Linux, BSD, or macOS (tested on Pop!_OS)

Build

make

The resulting file:

build/C64UHEX.PRG

Load on real hardware or emulator:

LOAD"C64UHEX.PRG",8,1
RUN

🧠 Technical Design Notes

Hex view is authoritative PETSCII is a representation, not the source of truth.
Strict module separation
- buffer → authoritative file access
- viewbuffer → paged cache
- ui/grid/screen → rendering only
- state/input → interaction logic
No dynamic allocation
- Deterministic memory usage
No ASCII assumptions
- All character handling is PETSCII-aware

📚 Educational & Preservation Notice

This application is provided freely for learning and historical preservation purposes. No fees are required to read, use, or share this material.

Optional Support

If you find this project helpful and wish to support the author, you may optionally buy me a beer via PayPal at:

PayPal: @floreseo

(Completely optional — education comes first.)

🤝 Collaboration & Contributions

Contributions are welcome and encouraged, especially from developers interested in:

cc65 development
PETSCII UI design
Commodore file systems
Retro-computing tooling

⚠️ Important Collaboration Policy

Please do NOT submit experimental or developmental changes to this main repository.

This repository is treated as a stable reference implementation.

👉 All active development, experimentation, and collaboration must occur in:

c64uhex2

Once features mature and stabilize, they may be selectively merged back into C64UHEX.

This policy exists to:

Preserve build stability
Maintain a clean historical baseline
Avoid breaking real hardware users

C64uhex

Install / Use

README