diff --git a/build/pdp10-ka/start b/build/pdp10-ka/start
index 53daea7d..c346fb52 100755
--- a/build/pdp10-ka/start
+++ b/build/pdp10-ka/start
@@ -38,8 +38,25 @@ type340() {
     cp build/pdp10-ka/run out/pdp10-ka/run
 }
 
+help() {
+    cat <<EOF
+This start script takes several command line arguments:
+
+help - Display this help text.
+type340 - Enable the Type 340 display.
+gt40 - Start a GT40 emulator.
+tv11 - Start a TV-11 emulator.
+tvcon - Start a TV display.
+
+EOF
+
+    touch out/pdp10-ka/nohelp
+}
+
 sed 's/set dpy enabled/set dpy disabled/' < build/pdp10-ka/run > out/pdp10-ka/run
 
+test -f out/pdp10-ka/nohelp || help
+
 while test -n "$1"; do
     "$1"
     shift