diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..7b0afb1
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,17 @@
+root = true
+
+[*]
+charset = utf-8
+# end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = tab
+indent_size = 2
+tab_width = 2
+
+[*.{yml,yaml}]
+indent_style = space
+indent_size = 2
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..e91b107
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,16 @@
+version: 2
+updates:
+  # Maintain GitHub Action runners
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    target-branch: dev
+    commit-message:
+      prefix: "[Dependabot]"
+    labels:
+      - Dependencies
+    assignees:
+      - Paebbels
+    reviewers:
+      - Paebbels
+    schedule:
+      interval: "daily"    # Checks on Monday trough Friday.
diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
new file mode 100644
index 0000000..4ed2d90
--- /dev/null
+++ b/.github/pull_request_template.md
@@ -0,0 +1,30 @@
+# New Features
+
+* tbd
+* tbd
+
+# Changes
+
+* tbd
+* tbd
+
+# Bug Fixes
+
+* tbd
+* tbd
+
+# Documentation
+
+* tbd
+* tbd
+
+# Unit Tests
+
+* tbd
+* tbd
+
+----------
+# Related Issues and Pull-Requests
+
+* tbd
+* tbd
diff --git a/.github/workflows/Pipeline.yml b/.github/workflows/Pipeline.yml
new file mode 100644
index 0000000..f2ecff7
--- /dev/null
+++ b/.github/workflows/Pipeline.yml
@@ -0,0 +1,46 @@
+name: Verification of setup-ghdl
+
+on:
+  push:
+  workflow_dispatch:
+
+jobs:
+  Setup-GHDL-Nightly:
+    name: ${{ matrix.os.icon }} Setup GHDL ${{ matrix.os.backend }} on ${{ matrix.os.name }}
+    runs-on: ${{ matrix.os.image }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - {'icon': '🐧', 'name': 'Ubuntu',  'image': 'ubuntu-24.04', 'shell': 'bash',      'runtime': '',       'backend': 'mcode'}
+          - {'icon': '🐧', 'name': 'Ubuntu',  'image': 'ubuntu-24.04', 'shell': 'bash',      'runtime': '',       'backend': 'llvm'}
+          - {'icon': '🐧', 'name': 'Ubuntu',  'image': 'ubuntu-24.04', 'shell': 'bash',      'runtime': '',       'backend': 'llvm-jit'}
+          - {'icon': '🐧', 'name': 'Ubuntu',  'image': 'ubuntu-24.04', 'shell': 'bash',      'runtime': '',       'backend': 'gcc'}
+          - {'icon': '🍎', 'name': 'macOS',   'image': 'macos-13',     'shell': 'bash',      'runtime': '',       'backend': 'mcode'}
+          - {'icon': '🍎', 'name': 'macOS',   'image': 'macos-13',     'shell': 'bash',      'runtime': '',       'backend': 'llvm'}
+          - {'icon': '🍏', 'name': 'macOS',   'image': 'macos-14',     'shell': 'bash',      'runtime': '',       'backend': 'llvm'}
+          - {'icon': '🪟', 'name': 'Windows', 'image': 'windows-2022', 'shell': 'powershell','runtime': '',       'backend': 'mcode'}
+          - {'icon': '🪟', 'name': 'Windows', 'image': 'windows-2022', 'shell': 'msys2 {0}', 'runtime': 'ucrt64', 'backend': 'mcode'}
+    defaults:
+      run:
+        shell: ${{ matrix.os.shell }}
+
+    steps:
+      - name: 🟦 Setup MSYS2 for ${{ matrix.os.runtime }}
+        uses: msys2/setup-msys2@v2
+        if: startsWith(matrix.os.shell, 'msys2')
+        with:
+          msystem: ${{ matrix.os.runtime }}
+          update: true
+
+      - name: Setup GHDL ${{ matrix.os.backend }}
+        uses: paebbels/setup-ghdl@dev
+        with:
+          version: nightly
+          backend: ${{ matrix.os.backend }}
+          runtime: ${{ matrix.os.runtime }}
+          investigate: true
+
+      - name: Verify
+        run: |
+          ghdl --version
diff --git a/README.md b/README.md
index 87f27de..7577cbb 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,69 @@
-# `setup-ghdl` GitHub Action
+# Setup GHDL in GitHub Action Workflows
+
+This composite action, installs GHDL in a GitHub Action's workflow job.
+
+
+## Features
+
+* Select GHDL version (tagged release or nightly build).
+* Select GHDL backend (LLVM, LLVM-JIT, mcode, GCC)
+* Activate an investigation mode (check and show GHDL installation, ...)
+* Supported runner OS' (automatically detected): Ubuntu 2024.04, macOS (x86-64), macOS (aarch64), Windows
+
+## Usage
+
+```yaml
+jobs:
+  MyJob:
+    steps:
+      - name: Run VHDL Simulation
+        uses: paebbels/setup-ghdl@v1
+        with:
+          version: nightly
+          backend: mcode
+          investigate: true
+```
+
+
+### Input Parameters
+
+| Parameter                  | Required | Default     | Description                                              |
+|----------------------------|:--------:|-------------|----------------------------------------------------------|
+| `version`                  |    no    | `'nightly'` | A tagged GHDL version starting at `v5.0.0` or `nightly`. |
+| `backend`                  |    no    | `'mcode'`   | GHDL backend: `llvm`, `llvm-jit`, `mcode`, `gcc`.        |
+| `investigate`              |    no    | `false`     | If enabled, details and check GHDL installation.         |
+
+
+### Output Parameters
+
+| Parameter          | Description |
+|--------------------|-------------|
+| `ghdl-binary-dir`  | tbd         |
+| `ghdl-library-dir` | tbd         |
+
+
+## Dependencies
+
+### On Linux (Ubuntu)
+
+* Further dependencies will be installed using `apt-get`.
+* GHDL will be added to `PATH`.
+
+### On macOS
+
+*tbd*
+
+### On Windows (native)
+
+
+### On Windows + MSYS2
+
+## Contributors
+
+* [Patrick Lehmann](https://GitHub.com/Paebbels) (Maintainer)
+* [and more...](https://GitHub.com/ghdl/setup-ghdl/graphs/contributors)
+
+### Credits
+
+This GitHub Action replaces `setup-ghdl-ci`, a Javascript Action developed by Umarcor, with a composite action using
+simples instructions (`curl`, `tar`, `apt-get`) written in Bash.
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..8c71f4d
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,228 @@
+name: Setup GHDL
+branding:
+  icon: play
+  color: gray-dark
+description: Install and setup GHDL downloaded from GHDL's release pages at GitHub.
+author: Patrick Lehmann (@Paebbels)
+
+inputs:
+  version:
+    type: string
+    required: false
+    default: 'nightly'
+  backend:
+    type: string
+    required: false
+    default: 'mcode'
+  runtime:
+    type: string
+    required: false
+    default: ''
+  install-directory:
+    type: string
+    required: false
+    default: 'install'
+  investigate:
+    type: boolean
+    required: false
+    default: false
+
+runs:
+  using: composite
+  steps:
+    - name: Variables
+      id: variables
+      shell: bash
+      run: |
+        tee "${GITHUB_OUTPUT}" <<EOF
+        nightly-version=5.0.0-dev
+        EOF
+
+    - name: Debugging
+      id: debug
+      shell: bash
+      run: |
+        echo "runner.os:   ${{ runner.os }}"
+        echo "runner.arch: ${{ runner.arch }}"
+
+    - name: Download and install GHDL on Ubuntu 2024.04 (x86-64)
+      id: ubuntu
+      if: runner.os == 'Linux' && runner.arch == 'X64'
+      shell: bash
+      run: |
+        ANSI_LIGHT_BLUE="\e[94m"
+        ANSI_NOCOLOR=$'\x1b[0m'
+
+        source /etc/lsb-release
+
+        if [[ "${DISTRIB_RELEASE}" != "24.04" ]]; then
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported Ubuntu version '${DISTRIB_RELEASE}'."
+          exit 1
+        else
+          printf "Runner:  %s\n" "Ubuntu ${DISTRIB_RELEASE} (x86-64)"
+        fi
+
+        if [[ "${{ inputs.version }}" == "nightly" ]]; then
+          VERSION_IN_URL="nightly"
+          VERSION_IN_FILE="${{ steps.variables.outputs.nightly-version }}"
+
+          printf "Version: %s\n" "nightly (${VERSION_IN_FILE})"
+        elif [[ "${{ inputs.version }}" =~ ^[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,2}$ ]]; then
+          VERSION_IN_URL="${{ inputs.version }}"
+          VERSION_IN_FILE="${{ inputs.version }}"
+
+          printf "Version: %s\n" "${{ inputs.version }}"
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported GHDL version '${{ inputs.version }}'."
+          exit 1
+        fi
+
+        if [[ "${{ inputs.backend }}" =~ ^mcode|llvm(-jit)?|gcc$ ]]; then
+          printf "Backend: %s\n" "${{ inputs.backend }}"
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported GHDL backend '${{ inputs.backend }}'."
+          exit 1
+        fi
+
+        (
+          printf "Creating installation directory '${{ inputs.install-directory }}' ...\n"
+          mkdir -p "${{ inputs.install-directory }}"
+          cd "${{ inputs.install-directory }}"
+
+          DOWNLOAD_URL="https://github.com/ghdl/ghdl/releases/download/${VERSION_IN_URL}/ghdl-${{ inputs.backend }}-${VERSION_IN_FILE}-ubuntu${DISTRIB_RELEASE}-x86_64.tar.gz"
+          printf "::group::${ANSI_LIGHT_BLUE}%s${ANSI_NOCOLOR}\n" "Downloading asset and extracting '${DOWNLOAD_URL}' file ..."
+          curl -L "${DOWNLOAD_URL}" | tar -xz --strip-components 1
+          printf "::endgroup::\n"
+
+          if [[ "${{ inputs.investigate }}" == "true" ]]; then
+            printf "::group::${ANSI_LIGHT_BLUE}%s.${ANSI_NOCOLOR}\n" "Content of '$(pwd)'"
+            tree -pash .
+            printf "::endgroup::\n"
+          fi
+
+          printf "::group::${ANSI_LIGHT_BLUE}%s.${ANSI_NOCOLOR}\n" "Installing dependencies from './ubuntu.requirements' using 'apt-get' ..."
+          sudo xargs --no-run-if-empty -a ./ubuntu.requirements -- apt-get install -y --no-install-recommends
+          printf "::endgroup::\n"
+        )
+
+        printf "Setting environment variable 'GHDL_PREFIX' ...\n"
+        tee "${GITHUB_ENV}" <<EOF
+        GHDL_PREFIX=$(pwd)/${{ inputs.install-directory }}/lib/ghdl
+        EOF
+
+        printf "Adding GHDL to 'PATH' ...\n"
+        tee "${GITHUB_PATH}" <<EOF
+        $(pwd)/${{ inputs.install-directory }}/bin
+        EOF
+
+        printf "Writing step outputs 'xxx' ...\n"
+
+    - name: Download and install GHDL on macOS (${{ runner.arch }})
+      id: macOSIntel
+      if: runner.os == 'macOS'  && ( runner.arch == 'X64' || runner.arch == 'ARM64' )
+      shell: bash
+      run: |
+
+        # TODO: check macOS version
+        if [[ "${{ runner.arch }}" == "X64" ]]; then
+          OS_RELEASE=13
+          OS_ARCH=x86_64
+        elif [[ "${{ runner.arch }}" == "ARM64" ]]; then
+          OS_RELEASE=14
+          OS_ARCH=aarch64
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported macOS architecture '${{ runner.arch }}'."
+          exit 1
+        fi
+        printf "macOS:   macOS %s - %s\n" "${OS_RELEASE}" "${OS_ARCH//_/-}"
+
+        if [[ "${{ inputs.version }}" == "nightly" ]]; then
+          VERSION_IN_URL="nightly"
+          VERSION_IN_FILE="${{ steps.variables.outputs.nightly-version }}"
+
+          printf "Version: %s\n" "nightly (${VERSION_IN_FILE})"
+        elif [[ "${{ inputs.version }}" =~ ^[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,2}$ ]]; then
+          VERSION_IN_URL="${{ inputs.version }}"
+          VERSION_IN_FILE="${{ inputs.version }}"
+
+          printf "Version: %s\n" "${{ inputs.version }}"
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported GHDL version '${{ inputs.version }}'."
+          exit 1
+        fi
+
+        if [[ "${{ inputs.backend }}" =~ ^mcode|llvm(-jit)?$ ]]; then
+          printf "Backend: %s\n" "${{ inputs.backend }}"
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported GHDL backend '${{ inputs.backend }}'."
+          exit 1
+        fi
+
+        (
+          printf "Creating installation directory '${{ inputs.install-directory }}' ...\n"
+          mkdir -p "${{ inputs.install-directory }}"
+          cd "${{ inputs.install-directory }}"
+
+          printf "Downloading asset and extracting tar.gz file ...\n"
+          curl -L "https://github.com/ghdl/ghdl/releases/download/${VERSION_IN_URL}/ghdl-${{ inputs.backend }}-${VERSION_IN_FILE}-macos${OS_RELEASE}-${OS_ARCH}.tar.gz" | tar -xz --strip-components 1
+          (
+            cd bin
+            pwd
+            ls -lAh .
+          )
+        )
+
+        printf "Setting environment variable 'GHDL_PREFIX' ...\n"
+        tee "${GITHUB_ENV}" <<EOF
+        GHDL_PREFIX=$(pwd)/${{ inputs.install-directory }}/lib/ghdl
+        EOF
+
+        printf "Adding GHDL to 'PATH' ...\n"
+        tee "${GITHUB_PATH}" <<EOF
+        $(pwd)/${{ inputs.install-directory }}/bin
+        EOF
+
+        printf "Writing step outputs 'xxx' ...\n"
+
+    - name: Download and install GHDL on Windows (native)
+      id: Windows
+      if: runner.os == 'Windows' && runner.arch == 'X64' && inputs.runtime == ''
+      shell: powershell
+      run: |
+        curl -L "https://github.com/ghdl/ghdl/releases/download/${VERSION_IN_URL}/mingw-w64-ucrt-x86_64-ghdl-mcode-5.0.0.dev-1-any.pkg.tar.zst" -o ghdl.pkg.tar.zst
+
+
+    - name: Download and install GHDL on Windows + UCRT64 (x86-64)
+      id: UCRT64
+      if: runner.os == 'Windows' && runner.arch == 'X64' && ( inputs.runtime == 'mingw64' || inputs.runtime == 'ucrt64' )
+      shell: ${{ inputs.shell }}
+      run: |
+        if [[ "${{ inputs.version }}" == "nightly" ]]; then
+          VERSION_IN_URL="nightly"
+          VERSION_IN_FILE="${{ steps.variables.outputs.nightly-version }}"
+
+          printf "Version: %s\n" "nightly (${VERSION_IN_FILE})"
+        elif [[ "${{ inputs.version }}" =~ ^[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,2}$ ]]; then
+          VERSION_IN_URL="${{ inputs.version }}"
+          VERSION_IN_FILE="${{ inputs.version }}"
+
+          printf "Version: %s\n" "${{ inputs.version }}"
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported GHDL version '${{ inputs.version }}'."
+          exit 1
+        fi
+
+        if [[ "${{ inputs.backend }}" =~ ^mcode|llvm(-jit)?$ ]]; then
+          printf "Backend: %s\n" "${{ inputs.backend }}"
+        else
+          printf "::error title=%s::%s\n" "setup-ghdl" "Unsupported GHDL backend '${{ inputs.backend }}'."
+          exit 1
+        fi
+
+        curl -L "https://github.com/ghdl/ghdl/releases/download/${VERSION_IN_URL}/mingw-w64-ucrt-x86_64-ghdl-mcode-5.0.0.dev-1-any.pkg.tar.zst" -o ghdl.pkg.tar.zst
+        pacman -U --noconfirm ghdl.pkg.tar.zst
+
+        which ghdl
+        ghdl version
+        echo "GHDL_PREFIX=$(realpath $(dirname $(which ghdl))/../lib/ghdl) >> $GITHUB_ENV"
+        echo "GHDL_PREFIX=$(realpath $(dirname $(which ghdl))/../lib/ghdl)" >> $GITHUB_ENV