Pronounced "Hondani Shell"
HDN Shell RR turns a Retro Replay cartridge on your C64 Ultimate into an AI-enabled, network-connected shell that lives alongside BASIC. You keep typing at the familiar READY. prompt: recognized shell commands run instantly in the cartridge, and anything BASIC doesn't understand is forwarded to the HDN Server — a companion app you run on your own PC or Mac — for AI chat, manual search, CSDB scene access, virtual console apps, and an AI coding agent that can see the screen, press keys, and inject compiled programs into the real machine.
Disassembled source code of the CyberpunX Retro Replay 3.8p cartridge contributes to historical preservation, educational analysis, and hardware maintenance of obsolete 8-bit systems. This repository honors the lineage of the original Retro Replay hardware created by Individual Computers, the community software enhancements by CyberpunX, and the foundational Action Replay concepts originally developed by Datel.
An earlier version of HDN Shell replaced the BASIC ROM entirely. That approach is now outdated and kept only as a legacy alternative installation.
- BASIC stays. Nothing is removed from your C64; the shell wedges into a Retro Replay cartridge and steps completely out of the way the moment you load or run a program.
- Simplified commands: Replace
LOAD "$",8,1withllordir. - Fast file management: Switch drives (
#9), mount disk images (mnt), copy files (cp), and more. - SD2IEC support: Use device
#s(with Ultimate), including directory navigation. - Integrated machine code monitor & freezer: courtesy of the Retro Replay cartridge itself, plus
memcpyfor saving/restoring arbitrary memory ranges to files. - HDN Server integration: connect for AI chat, CSDB browsing, a network drive, and a set of full server-side console apps (file editor, coding agent, web browser, Telegram, RSS reader, Wikipedia browser) — switch between them instantly with
C=+CTRL+<digit>. - Your machine, your server: run the HDN Server locally on your own PC or Mac — no hosted service, no account, any OpenAI-compatible LLM endpoint (including local Ollama).
- Open source: all code, including the server and the cartridge wedge source, is available.
- Searchable manual pages: find help fast, including a dedicated
m:<phrase>manual-search prefix. - AI chat: get assistance and answers right at the prompt — no prefix required, just type.
- Python expression execution: run Python expressions on the server with
?<expr>.
Ultimate/1541 Ultimate with networking required for HDN Server features.
- C64 hardware is legendary; Ultimate makes it even better.
- Today, C64 can be a serious computer for creative projects, learning, and fun.
- Command line = power. HDN Shell RR brings that power to your C64 — without giving up BASIC.
- Focus on productivity, not just nostalgia.
- Fast program injection from CSDB or the AI coding agent means less waiting, more doing.
- Server integration and networking make your C64 feel modern.
- Discover all the features HDN Shell RR brings to your C64!
- Multiple command line sessions (virtual consoles) — switch like Linux
- Clipboard between the server and the C64 (
C=+C/C=+V) - Prglets: relocatable small resident programs
- Resident programs handling frame interrupts
- SID/MOD background music streaming
- A community registry of third-party server apps and command handlers
See the Installation Guide for step-by-step instructions to set up the HDN Server on your PC and attach the HDN Shell RR cartridge to your C64 Ultimate.
- Type
helpat the command line for a list of available commands. - Get help on any topic:
help <command>orhelp <your question>. - Search the manual directly:
m:<search phrase>. - Or, read the User Manual.
This project is free to use and modify for educational and personal purposes.
Created by Honza with support from the Hondani gang.
Built with KickAssembler for the Commodore 64.