Retro ROMming with RP2350 5V GPIOs - One ROM

You asked, I delivered. This may be the FIRST real-world application of the brand new RP2350 A4 stepping for retro systems, taking advantage of the RP2350's newly qualified 5V tolerant GPIOs and the A4's fix for erratum E9. From the emotional first boot moment to PCB routing challenges in just 17x14mm, this video covers almost everything I learned building an RP2350-based ROM emulator. Including why the "cheaper than STM32" narrative isn't quite true, which MCU is faster Hz for Hz, overclocking up to 540MHz, and some mysterious XIP cache behaviour that crashed my cores. This is a deep dive into designing a tiny 2-layer RP2350 PCB, porting bare-metal firmware, and exploring the less talked about features needed to achieve cycle-level optimization for retro systems. There is a companion (more detailed) technical article to go alongside this episode: https://piers.rocks/2025/08/25/rp2350... 🔗 *Links* Technical article: https://piers.rocks/2025/08/25/rp2350... One ROM github: https://piers.rocks/u/one ⏰ *Timestamps* 00:00 🎬 Introduction 00:14 🎉 First Boot 00:47 📋 One ROM Overview 02:34 🎮 One ROM RP2350 Demo 04:20 🛠️ PCB Layout 18:05 💻 Firmware Porting 24:45 💰 Price Comparison 29:28 🔌 GPIO 5V Tolerance 31:56 🏁 Performance Comparison 35:15 🔥 Overclocking 36:30 💭 Final Thoughts Video content copyright (c) 2025 piers.media Limited. All rights reserved.