In this video I show why you no longer require jumpers or DIP switches to switch between ROM images in your retro system. With One ROM and its new ROM Bus Contol Protocol implementation, you can switch between ROM images on the fly using applications on the C64.

The ROM Bus Control Protocol is a new standard for retro systems to communicate with and control ROM emulators, such as One ROM. GRUB-style bootloaders are available for the Commodore 64 and VIC-20 using One ROM.

🔗 Links

Discord: https://discord.gg/tq22nJefXr
Buy: https://onerom.org/buy
GitHub: https://github.com/piersfinlayson/one-rom

ROM Bus Control Protocol: https://github.com/piersfinlayson/rom-bus-control-protocol/blob/main/spec/rbcp.md
C64 bootloader: https://github.com/piersfinlayson/rom-bus-control-protocol/tree/main/host-apps/c64-bootloader
VIC-20 bootloader: https://github.com/piersfinlayson/rom-bus-control-protocol/tree/main/reference/host/6502/vic20-boot

⏰ Timestamps

00:00 C64 Bootloader Demo
01:46 One ROM Introduction
03:07 Multi-ROM Switching Demo
04:15 VIC-20 Bootloader Demo
05:18 No Hardware Mods Required
05:48 ROM Refresher
07:33 Bi-directional Communication Overview
12:10 ROM Bus Control Protocol
17:54 6502 Host Applications
24:05 Challenges
26:00 Q&A
30:05 Wrap up

Video content copyright (c) 2026 piers.rocks Limited. All rights reserved.

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