PhotonTERM is a BBS terminal client for macOS, Linux, and Windows. It connects to bulletin board systems over Telnet and SSH with full ANSI/VT100/VT220 terminal emulation, a hardware-accelerated SDL2 display, and no external runtime dependencies on macOS.

• Terminal emulation - ANSI, VT100, VT220, DEC line drawing, 256-colour and truecolour (24-bit RGB) SGR, OSC window title, visual BEL flash
• Connection types - Telnet, SSH (libssh2), local shell (PTY)
• SSH authentication - ssh-agent, public key (Ed25519/ECDSA/RSA), password; host key fingerprint stored and verified per entry
• BBS dialing directory - INI-based list with add/edit/delete; per-entry SSH credentials; persistent across sessions
• SDL2 display - Terminus TTF font, Unicode, hardware-accelerated rendering, CP437 fallback for ANSI BBS art
• File transfer - ZModem, YModem, XModem via bundled lrzsz
• macOS - signed/notarizable app bundle; no Homebrew runtime dependencies; static-linked against bundled OpenSSL, libssh2, SDL2, SDL2_ttf
• Settings - font size, terminal size, visual bell toggle; persisted to INI

PhotonTERM needs SDL2, SDL2_ttf, libssh2, and OpenSSL 3.x. The included scripts/build-deps.sh builds all of them from source into 3rdp/prefix/, which both CMake and GNUmakefile pick up automatically.

bash scripts/build-deps.sh all

Alternatively, install system packages (Linux/Windows only — not for macOS distribution builds, which must use build-deps.sh to produce a statically-linked, Gatekeeper-clean app):

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

# macOS: app bundle at
build/src/photonterm/PhotonTERM.app

# Linux/Windows: binary at
build/src/photonterm/photonterm

CMake finds bundled deps in 3rdp/prefix/ automatically when present. Falls back to system packages otherwise.

# Debug build (macOS / Linux)
make -C src/photonterm

# Release build
make -C src/photonterm RELEASE=1

# Windows (MinGW64 in MSYS2)
make -C src/photonterm win=1 RELEASE=1

# Verbose build
make -C src/photonterm QUIET=""

GNUmakefile output directories:

• macOS: src/photonterm/clang.darwin.arm64.exe.debug/PhotonTERM.app
• Linux: src/photonterm/gcc.linux.x86_64.exe.debug/photonterm
• Windows: src/photonterm/mingw.win32.x86_64.exe.release/photonterm.exe

# Ad-hoc (local use only)
codesign --force --deep --sign - \
  build/src/photonterm/PhotonTERM.app

# Developer ID (distribution)
bash scripts/sign-macos.sh build/src/photonterm/PhotonTERM.app

PhotonTERM tries authentication in order:

1. ssh-agent via $SSH_AUTH_SOCK (macOS Keychain, gpg-agent, 1Password, etc.)
2. ~/.ssh/id_ed25519
3. ~/.ssh/id_ecdsa
4. ~/.ssh/id_rsa
5. Password from the BBS entry or prompted at connect time

Host key fingerprints are stored per-entry and verified on subsequent connections. Mismatches prompt the user before proceeding.

ZModem, YModem, and XModem transfers are handled via lrzsz (sz/rz), built by scripts/build-deps.sh and bundled into the macOS app bundle. Trigger transfers from within a BBS session as you normally would; PhotonTERM detects the protocol negotiation automatically.

PhotonTERM sets TERM_PROGRAM=PhotonTERM for local shell sessions. macOS /etc/bashrc and /etc/zshrc source /etc/bashrc_$TERM_PROGRAM and /etc/zshrc_$TERM_PROGRAM respectively. To get a colored prompt in PhotonTERM shells, create one or both of these files:

# /etc/bashrc_PhotonTERM
export PS1='\[\033[01;32m\]\h:\[\033[01;34m\]\W \$\[\033[00m\] '

# /etc/zshrc_PhotonTERM
export PROMPT='%F{green}%m%f:%B%F{blue}%1~%f%b %f%# '

Alternatively, set your prompt in ~/.bashrc or ~/.zshrc directly - those files are sourced regardless of TERM_PROGRAM.

Stored as an INI file:

Settings are persisted separately from the BBS list:

GitHub Actions (.github/workflows/build.yml) builds for:

All platforms build with scripts/build-deps.sh and cache dependencies via actions/cache for fast incremental CI runs.

photonterm/
├── src/photonterm/           # All PhotonTERM source
│   ├── photon_main.c         # Entry point, SDL init, main loop
│   ├── photon_vte.c/h        # ANSI/VT100/VT220 terminal emulator
│   ├── photon_sdl.c/h        # SDL2 + SDL2_ttf display and keyboard
│   ├── photon_ui.c/h         # Text-mode UI widgets (menus, lists, input)
│   ├── photon_bbslist.c/h    # BBS dialing directory UI
│   ├── photon_conn.c/h       # Network transport (Telnet, SSH, PTY)
│   ├── photon_term.c/h       # Terminal I/O loop
│   ├── photon_store.c/h      # INI-based BBS list persistence
│   ├── photon_settings.c/h   # App settings persistence
│   ├── photon_xfer.c/h       # File transfer (ZModem/YModem/XModem)
│   ├── photon_debug.c/h      # Debug log (--debug flag)
│   ├── photon_compat.h       # POSIX portability (asprintf, strlcpy, etc.)
│   ├── photon_paths.h        # Config path enum + photon_mkdir_p()
│   ├── photon_bbs.h          # BBS entry struct
│   ├── photon_cp437_font.c/h # Built-in CP437 bitmap font (fallback)
│   ├── DarwinWrappers.m/h    # macOS Objective-C (app delegate, paths)
│   ├── early_init.c          # Pre-SDL signal/env setup (Linux, constructor)
│   ├── Info.plist            # macOS app bundle metadata
│   ├── CMakeLists.txt        # CMake build rules
│   └── GNUmakefile           # GNU make build rules
├── scripts/
│   ├── build-deps.sh         # Builds OpenSSL, libssh2, SDL2, SDL2_ttf, lrzsz
│   ├── release.sh            # Version bump, commit, annotated tag
│   ├── sign-macos.sh         # macOS Developer ID signing + notarization
│   └── patches/              # Patches applied by build-deps.sh
├── CMakeLists.txt            # Root CMake project file
├── 3rdp/                     # Bundled dep build output (gitignored)
├── AGENTS.md                 # Technical reference for development
├── ICONS.md                  # Icon specification and generation guide
└── README.md                 # This file

PhotonTERM uses calendar versioning: YYYYMMDD.N (e.g., 20260314.1).

./scripts/release.sh           # auto-compute next version for today
./scripts/release.sh 20260314.2  # explicit version

PhotonTERM is distributed under the GNU General Public License v3.0 (GPLv3).

Third-party licenses:

• libssh2: BSD 3-Clause
• OpenSSL: Apache 2.0
• SDL2 / SDL2_ttf: zlib License
• Terminus TTF: SIL Open Font License 1.1
• lrzsz: GNU GPL v2+