diff --git a/Makefile b/Makefile
index 73aa2338..662def73 100644
--- a/Makefile
+++ b/Makefile
@@ -51,7 +51,7 @@ KA10=tools/sims/BIN/ka10
 ITSTAR=tools/itstar/itstar
 WRITETAPE=tools/tapeutils/tapewrite
 MAGFRM=tools/dasm/magfrm
-GT40=$(OUT)/bootvt.img
+GT40=tools/simh/BIN/pdp11 $(OUT)/bootvt.img
 
 H3TEXT=$(shell cd build; ls h3text.*)
 SMF:=$(addprefix tools/,$(addsuffix /.gitignore,$(SUBMODULES)))
@@ -192,6 +192,9 @@ tools/supdup/supdup:
 $(SMF):
 	$(GIT) submodule update --init `dirname $@`
 
+tools/simh/BIN/pdp11:
+	$(MAKE) -C tools/simh pdp11
+
 check-dirs: Makefile
 	mkdir -p $(OUT)/check
 	echo $(SRC) | tr ' ' '\n' | sort > $(OUT)/check/src1
diff --git a/README.md b/README.md
index f3b32bef..7050be4a 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,10 @@ CONSOLE`.  You are now ready to log in, so type Control-Z.  See
 [doc/DDT.md](doc/DDT.md) for a list of useful commands.  When done,
 shut down orderly by typing `:lock` and then `5down`.
 
+ITS can optionally use some additional peripheral devices.  To attach
+a simulated GT40 graphics terminal, type `./start gt40` when booting
+ITS.
+
 To install your personal user files, add a subdirectory under `user`
 with your files inside.  They will be copied to ITS.  The directory
 name is limited to six characters, and file names must have two
diff --git a/build/simh/gt40 b/build/simh/gt40
new file mode 100644
index 00000000..815f9dd7
--- /dev/null
+++ b/build/simh/gt40
@@ -0,0 +1,16 @@
+set cpu 11/05
+set cpu 16k
+set tti 8b
+set dli enabled
+set dlo enabled
+set dli lines=1
+set dli address=17775610
+set dlo 8b
+at dli 10005,connect=localhost:10004
+set vt enable
+set vt crt=vr14
+set vt scale=1
+set vt address=17772000
+set rom enabled
+at rom out/sims/bootvt.img
+go 166000
diff --git a/build/simh/start b/build/simh/start
index 79e88784..d3f3a218 100755
--- a/build/simh/start
+++ b/build/simh/start
@@ -1,3 +1,22 @@
 #!/bin/sh
 
+gt40() {
+    trap kill_gt40 0
+    (sleep 3; tools/simh/BIN/pdp11 build/sims/gt40 >gt40.log 2>&1) &
+    GT40="$!"
+    echo "GT40 started, pid $GT40"
+}
+
+kill_gt40() {
+    kill "$GT40"
+    sleep 1
+    kill -9 "$GT40"
+    echo "GT40 stopped"
+}
+
+while test -n "$1"; do
+    "$1"
+    shift
+done
+
 tools/simh/BIN/pdp10 build/simh/boot
diff --git a/build/sims/gt40 b/build/sims/gt40
new file mode 100644
index 00000000..2381f869
--- /dev/null
+++ b/build/sims/gt40
@@ -0,0 +1,17 @@
+set cpu 11/05
+set cpu 16k
+set tti 8b
+set dli enabled
+set dlo enabled
+set dli lines=1
+set dli address=17775610
+set dlo 8b
+at dli 10005,connect=localhost:10000
+set vt enable
+set vt crt=vr14
+set vt scale=1
+set vt address=17772000
+set rom enabled
+set rom0 address=17766000
+at rom0 out/sims/bootvt.img
+boot rom0
diff --git a/build/sims/start b/build/sims/start
index 65085a5f..5bf042ed 100755
--- a/build/sims/start
+++ b/build/sims/start
@@ -1,3 +1,22 @@
 #!/bin/sh
 
+gt40() {
+    trap kill_gt40 0
+    (sleep 3; tools/simh/BIN/pdp11 build/sims/gt40 >gt40.log 2>&1) &
+    GT40="$!"
+    echo "GT40 started, pid $GT40"
+}
+
+kill_gt40() {
+    kill "$GT40"
+    sleep 1
+    kill -9 "$GT40"
+    echo "GT40 stopped"
+}
+
+while test -n "$1"; do
+    "$1"
+    shift
+done
+
 tools/sims/BIN/ka10 build/sims/run
diff --git a/tools/simh b/tools/simh
index 49911369..e1db7dec 160000
--- a/tools/simh
+++ b/tools/simh
@@ -1 +1 @@
-Subproject commit 49911369d0c7eebc802d8ee871292cd5357b5c6c
+Subproject commit e1db7dec41098cc7e22d2b379a26a7c4561dfa14