diff --git a/build/klh10/start b/build/klh10/start
index 2e6157c3..e1b4f38d 100755
--- a/build/klh10/start
+++ b/build/klh10/start
@@ -4,5 +4,40 @@
 SUDO=sudo
 #NET_DEFAULT_IF=eth1
 
+EXIT=:
+trap "" QUIT INT TERM
+
+started() {
+    EXIT="$EXIT;stop $1 $2"
+    trap "$EXIT" EXIT
+    echo "$1 started, pid $2"
+}
+
+stop() {
+    echo -n "Stopping $1... "
+    kill "$2" 2> /dev/null
+    sleep 2
+    kill -9 "$2" 2> /dev/null
+    echo "OK"
+}
+
+help() {
+    cat <<EOF
+This start script takes several command line arguments:
+
+help - Display this help text.
+
+EOF
+
+    touch out/klh10/nohelp
+}
+
+test -f out/klh10/nohelp || help
+
+while test -n "$1"; do
+    "$1"
+    shift
+done
+
 cd build/klh10
 $SUDO KLH10_NET_DEFAULT_IF=$NET_DEFAULT_IF ./kn10-ks-its dskdmp.ini
diff --git a/build/pdp10-kl/start b/build/pdp10-kl/start
index c2983eb5..93ea1988 100755
--- a/build/pdp10-kl/start
+++ b/build/pdp10-kl/start
@@ -17,6 +17,19 @@ stop() {
     echo "OK"
 }
 
+help() {
+    cat <<EOF
+This start script takes several command line arguments:
+
+help - Display this help text.
+
+EOF
+
+    touch out/pdp10-kl/nohelp
+}
+
+test -f out/pdp10-kl/nohelp || help
+
 while test -n "$1"; do
     "$1"
     shift
diff --git a/build/simh/start b/build/simh/start
index e42210f7..60992ef1 100755
--- a/build/simh/start
+++ b/build/simh/start
@@ -1,22 +1,45 @@
 #!/bin/sh
 
-gt40() {
-    trap kill_gt40 0
-    (sleep 3; tools/simh/BIN/pdp11 build/simh/gt40 >gt40.log 2>&1) &
-    GT40="$!"
-    echo "GT40 started, pid $GT40"
+EXIT=:
+trap "" QUIT INT TERM
+
+started() {
+    EXIT="$EXIT;stop $1 $2"
+    trap "$EXIT" EXIT
+    echo "$1 started, pid $2"
 }
 
-kill_gt40() {
-    kill "$GT40"
-    sleep 1
-    kill -9 "$GT40"
-    echo "GT40 stopped"
+stop() {
+    echo -n "Stopping $1... "
+    kill "$2" 2> /dev/null
+    sleep 2
+    kill -9 "$2" 2> /dev/null
+    echo "OK"
 }
 
+gt40() {
+    (sleep 3; tools/simh/BIN/pdp11 build/simh/gt40 >gt40.log 2>&1) &
+    started GT40 "$!"
+}
+
+help() {
+    cat <<EOF
+This start script takes several command line arguments:
+
+help - Display this help text.
+gt40 - Start a GT40 emulator.
+
+EOF
+
+    touch out/simh/nohelp
+}
+
+test -f out/simh/nohelp || help
+
 while test -n "$1"; do
     "$1"
     shift
 done
 
 tools/simh/BIN/pdp10 build/simh/boot
+exit 0