a3270

An x3270-aligned IBM 3270 mainframe terminal emulator for Android, written in Kotlin using Jetpack Compose and powered by the lib3270j protocol engine from j3270. Designed for mobile access to IBM z/OS, z/VM, CMS, and TSO systems over TN3270 and TN3270E.

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🔗 Repositories

• a3270 (Android App): https://git.hugfreevikings.wtf/rudi/a3270
• j3270 (Desktop App & lib3270j Core Library): https://git.hugfreevikings.wtf/rudi/j3270

a3270 relies on the shared 3270 protocol library (lib3270j) provided by the j3270 repository.

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🚀 Quick Download & Install

Latest Standalone APK

You can download ready-to-install Android APKs directly from releases or CI builds:

• Download Latest Tagged Release (a3270.apk)
• Latest Nightly CI Artifacts (Download under the latest successful workflow run)

Installing a3270

To install the APK on a connected Android device or emulator via adb:

adb install -r a3270.apk

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✨ Features

• Modern Jetpack Compose UI: Responsive, touch-optimized 3270 terminal screen rendering.
• TN3270 & TN3270E Protocol Support: RFC 2355 compliant state machine, negotiation, Device-Type query, and SSL/TLS encryption via lib3270j.
• On-Screen Function Key Bar: Quick-access touch bar for PF1–PF24, PA1–PA3, Enter, Clear, Reset, and Attn keys.
• IND$FILE File Transfer: Full mobile UI for CUT and DFT (DDM) high-speed structured field file transfers with ASCII/binary translation, CRLF handling, and recfm/lrecl formatting for TSO, VM/CMS, and CICS.
• OIA Status Line: Real-time Operator Information Area displaying connection state, keyboard lock, insert mode, cursor row/col, and LU name.
• Host Profile Storage: Save and manage multiple mainframe connection profiles with custom ports, models, and SSL/TLS options.
• Background Session Persistence: Android foreground service keeps your terminal session alive when multitasking.
• Terminal Models:
  • Model 2 (24x80)
  • Model 3 (32x80)
  • Model 4 (43x80)
  • Model 5 (27x132)

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🛠️ Building from Source

Prerequisites

• Java Development Kit (JDK): JDK 17 or JDK 21
• Android SDK: API 34 platforms and build-tools (ANDROID_HOME or ANDROID_SDK_ROOT set)

1. Clone Repositories Side-by-Side

For the easiest setup, clone both j3270 and a3270 into the same parent folder:

git clone https://git.hugfreevikings.wtf/rudi/j3270.git
git clone https://git.hugfreevikings.wtf/rudi/a3270.git
cd a3270

Note: If j3270 is located in another directory, specify its location via the J3270_DIR environment variable:

export J3270_DIR=/path/to/j3270

or via Gradle property:

./gradlew assembleDebug -Pj3270Dir=/path/to/j3270

2. Build the Debug APK

Using the helper script:

./build.sh

Or using Gradle Wrapper directly:

./gradlew assembleDebug

The compiled APK will be generated at:

build/outputs/apk/debug/a3270-debug.apk

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🏷️ How to Tag & Publish (Beta) Releases

Releases can be published automatically to Gitea via Git tags:

# 1. Create a version tag (stable or beta)
git tag -a v0.1.0-beta.1 -m "Release v0.1.0-beta.1"

# Or a stable release:
git tag -a v0.1.0 -m "Release v0.1.0"

# 2. Push the tag to Gitea
git push origin v0.1.0-beta.1

Pushing any v* tag triggers the automated release workflow (.gitea/workflows/release.yaml), which:

1. Automatically detects pre-releases (tags containing beta, alpha, rc, pre, preview, or dev) and marks them as Pre-release on Gitea.
2. Builds the APK and packages it.
3. Publishes a new Gitea Release with a3270.apk attached automatically.

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🔍 Topics & Discoverability

Suggested keywords/topics for repository indexing: tn3270 · tn3270e · ibm-3270 · mainframe · terminal-emulator · android · android-app · jetpack-compose · kotlin · x3270 · j3270 · ind-file · file-transfer · ebcdic · z-vm · z-os · cms · tso · cics

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🤝 Contributing

Contributions are welcome! Please feel free to open a bug report or feature request via the Gitea issue tracker.

I have contributed no code to this project, it was entirely written by LLMs with my guidance only.

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📜 Acknowledgements

• j3270 — Desktop emulator and lib3270j protocol engine
• x3270 — Reference C implementation and protocol specifications
• Antigravity
• Claude Opus 4.6
• Gemini 3.1 Pro
• Gemini 3.7 Flash