A native macOS front-end for sdltrs / sdl2trs (Jens Günther's SDL2 fork of SDLTRS, https://gitlab.com/jengun/sdltrs). It gives you a real Cocoa window with machine presets, four floppy slots, two hard-disk slots, and ROM / config / character-set controls, then launches the emulator underneath with the right command line.

It is a launcher, not a new emulator. The running emulator window is still sdltrs. This fixes the disk-loading and configuration friction — not the in-emulator menus.

Originally built for a Model I with the HRG-1B high-resolution graphics card; now also covers Model III / 4 / 4P and the TCS Genie IIIs (which runs CP/M, G-DOS, and NEWDOS). HRG-1B emulation is automatic in Model I mode, so no extra flag is needed.

Version 1.1 · GPLv3 · © 2026 Egbert Schröer

TRS80Launcher/
├── README.md           ← this file
├── CHANGELOG.md        ← version history
├── LICENSE             ← GNU GPL v3.0 (full text)
├── build.sh            ← compiles the app
├── update-sdltrs.sh    ← pulls + rebuilds the sdltrs emulator (optional)
├── Info.plist          ← app bundle metadata
├── .gitignore
└── Sources/
    └── main.swift      ← the entire app (SwiftUI)

Important layout note: main.swift must live inside the Sources/ subfolder. If it ends up loose next to build.sh, the build fails with "error opening input file 'Sources/main.swift'". Fix: mkdir -p Sources && mv main.swift Sources/.

• macOS 13 (Ventura) or newer
• Xcode command-line tools (provides the swiftc compiler)
• A working macOS build of sdltrs — from https://gitlab.com/jengun/sdltrs. You want the macOS Unix executable (named sdltrs or sdl2trs64), not the .exe Windows file. The included update-sdltrs.sh can build it for you (see below).

Everything happens in the VS Code terminal (Terminal → New Terminal).

swiftc --version

If it prints a version, continue. If it says command not found, install the tools (click Install in the dialog, then wait):

xcode-select --install

If it replies "Command line tools are already installed", you're done.

In VS Code: File → Open Folder → select the project folder. Open a terminal; it will already point here. Confirm with ls that you see build.sh, Info.plist, README.md, and Sources.

chmod +x build.sh
./build.sh

On success it prints Done. Launch with: open TRS80Launcher.app.

open TRS80Launcher.app

If macOS blocks it ("unidentified developer"), right-click TRS80Launcher.app in Finder → Open → Open. Only needed once.

Because the source file is named main.swift, Swift treats it as top-level code, which collides with the @main attribute:

error: 'main' attribute cannot be used in a module that contains top-level code

The fix is the -parse-as-library flag, already included in build.sh. If you compile by hand, use:

swiftc -O -parse-as-library -framework SwiftUI -framework AppKit \
  -o TRS80Launcher Sources/main.swift

Then assemble the bundle (also what build.sh does):

rm -rf TRS80Launcher.app
mkdir -p TRS80Launcher.app/Contents/MacOS TRS80Launcher.app/Contents/Resources
cp Info.plist TRS80Launcher.app/Contents/Info.plist
mv TRS80Launcher TRS80Launcher.app/Contents/MacOS/TRS80Launcher
chmod +x TRS80Launcher.app/Contents/MacOS/TRS80Launcher
codesign --force --deep --sign - TRS80Launcher.app
open TRS80Launcher.app

1. Machine — pick a preset (top-right): Model I · HRG-1B, Model III, Model 4, Model 4P, or TCS Genie IIIs. The preset sets the model number and, for the Genie IIIs, enables the German/Genie character set. (The Genie IIIs runs CP/M, G-DOS, and NEWDOS — pick whichever the disk you're booting uses.)
2. Locate sdltrs — point this at your sdltrs (or sdl2trs64) binary. See the next section if the file appears greyed out. If you built the binary with update-sdltrs.sh, the installed source version (tag, commit hash, and date — e.g. 1.2.35 (e699d607, 2026-06-19)) is shown next to the path. sdltrs has no --version flag, so this is read from a sdltrs-version.txt the build script writes beside the binary; locate a binary built another way and the version simply doesn't show.
3. Floppy drives 0–3 — drag a .dmk / .dsk onto a slot, or use the folder button. Maps to -disk0…-disk3 (0-based).
4. Hard disks 0–3 — drag a .hdv onto a slot. Maps to -hard0…-hard3. When a preset has a known geometry (e.g. the Genie IIIs at 2460 cyl · 4 heads · 9 sec) it's shown as a label; sdltrs reads the real geometry from the .hdv itself.
5. Config (.t8c) — optional. Passed first so it loads before boot, preserving double-density and per-drive geometry.
6. ROM — optional. For a standard Model I boot you usually don't need it; if the emulator complains, pick your LEVEL2.ROM. Required for Genie / TCS setups.
7. German / Genie character set — adds -charset1 genie.
8. Boot (or press Return).

All settings persist between launches.

No-floppy hang: if both floppy and hard-disk slots are empty, the launcher adds -nofloppy so the emulator drops into ROM BASIC instead of hanging on a black screen. A hard-disk-only boot is not affected.

A bare Unix executable can appear non-selectable in the file dialog. Easiest fix first:

A. Set the path from the terminal (most reliable). Find the binary's full path (in Finder, right-click → hold Option → Copy "sdltrs" as Pathname), then:

defaults write name.schroeer.trs80launcher sdltrsPath "/full/path/to/sdltrs"

Quit the launcher (Cmd+Q) and reopen it. Example:

defaults write name.schroeer.trs80launcher sdltrsPath \
  "$HOME/Documents/GitHub/TRS80M1/sdltrs"

B. Go-to-folder in the dialog. Locate… → Cmd+Shift+G, paste the full path, Return, Open.

C. Rebuild. The current main.swift already removes the file-type filter, so a fresh ./build.sh makes the binary directly clickable.

An optional helper that pulls the latest sdltrs from GitLab and rebuilds it. It is on-demand (you run it; it is not a background job) and only rebuilds when the pull actually brings new commits.

One-time setup:

brew install cmake sdl2

Run:

chmod +x update-sdltrs.sh
./update-sdltrs.sh          # add --force to rebuild without changes

Edit the two paths at the top first:

• SRC_DIR — where the emulator source is cloned (a separate folder; the emulator's source never goes into this repo)
• INSTALL_DIR — where the built binary lands (point your launcher here)

Alongside the binary the script writes sdltrs-version.txt (the tag, commit hash, and date of the source it built). The launcher reads this to show the installed sdltrs version next to its path. It also prints the version when it runs, and the commit hash lets you crosscheck against GitLab's master to confirm you're current.

The script builds sdltrs the emulator, which is separate from this launcher. Only the script lives in this repo; the cloned source stays outside it. It builds the sdl2 branch (Jens Günther's recommendation): hardware/texture rendering and a mouse-resizable window, versus the master branch's software renderer and fixed window. The resulting binary is named sdl2trs. Verified working on Apple Silicon with Homebrew SDL2 (the build includes hard-disk and Genie/clone support).

Model I with a config, ROM, and a disk in drive 0:

sdltrs sdltrsTRS80.t8c -model1 -rom LEVEL2.ROM -disk0 esnd-01.dmk

Genie IIIs with two hard-disk volumes:

sdltrs -model3 -rom genie.rom -charset1 genie \
  -hard0 g3s-hard21-f1.hdv -hard1 g3s-hard21-f2.hdv

For a .app target, the launcher prefixes open … --args automatically.

• error opening input file 'Sources/main.swift' — main.swift is in the wrong place. mkdir -p Sources && mv main.swift Sources/.
• 'main' attribute cannot be used… — missing -parse-as-library; use build.sh or the hand-compile line above.
• sdltrs greyed out in Locate — see the section above; defaults write always works.
• .onChange deprecation warning (macOS 14+) — harmless; the code uses the form that compiles on both macOS 13 and 14+.
• HRG-1B graphics don't render — emulator/config matter, not a launcher bug. Confirm Model I mode and that the disk drives the HRG-1B.
• update-sdltrs.sh build fails — almost always a missing dependency; run brew install cmake sdl2. The build is otherwise verified working on Apple Silicon; if a repo change relocates the binary, the script reports that it couldn't find it.

This launcher is free software under the GNU General Public License v3.0 — see LICENSE for the full text.

TRS80Launcher — a native macOS front-end for sdltrs
Copyright (C) 2026 Egbert Schröer

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

sdltrs itself is separate software under its own BSD 2-Clause license by Jens Günther; this launcher only invokes it and does not include its code. (BSD-2-Clause is GPL-compatible, so there is no conflict.)