# 64KEY ROM PATCH enables persistent keyboard remapping for Commodore 64

> **Key takeaway:** A new tool allows users to patch Commodore 64 KERNAL ROM maps to create permanent, hardware-level keyboard remappings.

**Published:** 2026-10-30T14:58:52+00:00 
**Source:** Adafruit Electronics 
**Category:** open-hardware 
**Canonical URL:** https://fosswire.org/news/64key-rom-patch-enables-persistent-keyboard-remapping-for-co.html 

## Summary
Developer Dave VW has introduced 64KEY ROM PATCH, a utility designed to overcome the limitations of previous Commodore 64 keyboard remapping methods. Historically, remapping drivers were loaded into BASIC RAM at fixed addresses, meaning any changes were lost upon a system restart. This new approach targets the KERNAL ROM directly, where the four primary keyboard maps—Normal, Shift, Commodore, and Control—are stored.

The tool functions by locating these specific maps within the ROM and applying a patch list derived from DATA statements. This process allows for the creation of a customized ROM image that can be used in emulators or burned onto physical EEPROMs for real hardware. The included default table modifies several symbols, such as remapping '+' to '-', '@' to '[', and 'shift-:' to a standard colon.

## Technical implementation of 64KEY ROM PATCH
- **ROM Modification Logic:** The utility identifies the four internal KERNAL ROM keyboard maps (Normal, Shift, Commodore, and Control) and applies patches consisting of shift masks, key scan codes, and PETSCII characters.
- **Persistence Mechanisms:** Unlike previous RAM-based drivers, the patched image can be saved as a file, transferred to a PC, and burned to an EEPROM for permanent hardware installation.
- **Hardware and Emulation Compatibility:** The resulting ROM can be utilized by users with hardware ROM switchers like the Easy Flash 3 or via physical toggle switches, and is equally compatible with software emulators.
- **Data Structure:** The remapping is driven by a patch list provided through DATA statements, allowing for granular control over specific key behaviors.

## Why it matters
This development provides a robust solution for retro-computing enthusiasts and hardware hackers looking to modernize legacy input interfaces. By moving remapping from volatile RAM to persistent ROM, it enables more reliable hardware configurations for both physical Commodore 64 systems and software emulators.