RetroBridge: Five Computers, One Time Machine

RetroBridge is a Raspberry Pi 5 computing time machine that turns a 3.5-inch 480×320 touchscreen into a hands-on journey through five formative personal computers:

1976 — Apple-1 1977 — TRS-80 Model I 1977 — Apple II 1981 — IBM PC 1982 — Commodore 64

The goal was not to build another emulator launcher. I wanted RetroBridge to behave like a small interactive computing-history exhibit: power it on, select a year, and enter a usable computing environment from that period.

The photographs in this project show the actual working RetroBridge appliance. The beige period-style enclosure images are concept renderings for a future physical enclosure and are clearly separated from the validated hardware.

How it works

RetroBridge boots directly into a custom Time Machine interface instead of presenting a normal Linux desktop.

Each historical environment is handled separately:

RetroBridge provides the layer around those systems:

The 480×320 challenge

The small touchscreen became one of the main engineering constraints.

TRS-80 uses a deliberately sized terminal. DOSBox uses appliance-specific fullscreen settings. VICE runs without doubled rendering.

EWM required a more specific solution. Its Apple-1 and Apple II SDL windows normally open at approximately 3× logical scale, which is far too large for a 480×320 panel.

RetroBridge therefore provides two small source patches that change the relevant window/logical dimensions to 1× before EWM is compiled.

This allows both Apple environments to fit the RetroBridge screen while keeping the upstream emulator separate from the RetroBridge repository.

Trixie and the display startup problem

Rebuilding RetroBridge on a fresh Debian 13 Trixie card uncovered another issue.

The MHS35-style touchscreen driver starts its graphical environment through spi-display.service, which creates a root-owned X11 session rather than using the older LightDM startup path.

RetroBridge therefore includes a Trixie-specific X-session wrapper that grants the normal project user access to display :0 and starts the frontend from the active LXDE session.

The validated startup path is:

Power → SPI framebuffer → spi-display.service → Xorg :0 → LXDE → RetroBridge

Reproducibility

RetroBridge has passed two separate validation tests.

Full-card recovery: The known-good V1.1 microSD was imaged, SHA-256 verified, restored to another card, and successfully boot-tested.

Fresh public build: A different 32 GB microSD was started from a clean Debian 13 Trixie installation. Using the public RetroBridge project plus dependencies obtained from upstream sources, the clean build successfully reproduced:

Publication model

RetroBridge is an integration platform, not a software archive.

The repository contains RetroBridge-authored code, launchers, configuration guidance, patches, documentation, sample programs, and artwork.

It does not redistribute proprietary ROM collections, commercial operating systems, games, disk images, or third-party emulator source trees/binaries.

What is real today?

Validated and working:

Still under development:

The current working appliance uses the off-the-shelf touchscreen enclosure shown in the real project photographs.

Source and build guide

GitHub: https://github.com/retrobridge-jc/RetroBridge

Step-by-step build guide: https://www.instructables.com/RetroBridge-Build-a-Raspberry-Pi-5-Computing-Time-/

Five Computers. Six Years. One Computing Time Machine.