diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 79f31fdc..5bffc647 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -14,7 +14,8 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-22.04]
-        emulator: [simh, klh10, pdp10-ka, pdp10-kl, pdp10-ks]
+        #emulator: [simh, klh10, pdp10-ka, pdp10-kl, pdp10-ks]
+        emulator: [klh10]
     steps:
       - uses: actions/checkout@v2
       - name: Install dependencies
@@ -23,7 +24,7 @@ jobs:
         if: ${{runner.os == 'Linux'}}
         run: sh -ex build/dependencies.sh install_linux
       - name: Build
-        run: make check-dirs all EMULATOR=${{matrix.emulator}}
+        run: make check-dirs all EMULATOR=${{matrix.emulator}} MCHN=LC
       - name: Deploy
         if: github.ref == 'refs/heads/master'
         env:
diff --git a/tools/sims b/tools/sims
index 48186c90..5ea1a264 160000
--- a/tools/sims
+++ b/tools/sims
@@ -1 +1 @@
-Subproject commit 48186c90c49b3711090720fb38f3f88010ef576b
+Subproject commit 5ea1a2644c3afe9c5203c38840200d1f2f8af6d7