CI build using GitHub Actions.

.github/workflows/build.yml

@@ -0,0 +1,24 @@
+name: Build
+
+on: [push, pull_request]
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  build:
+    runs-on: ${{matrix.os}}
+    strategy:
+      matrix:
+        os: [ubuntu-18.04]
+        emulator: [simh, klh10, pdp10-ka, pdp10-kl]
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        env:
+          EMULATOR: ${{matrix.emulator}}
+        if: ${{runner.os == 'Linux'}}
+        run: sh -ex build/dependencies.sh install_linux
+      - name: Build
+        run: make check-dirs all EMULATOR=${{matrix.emulator}}