diff --git a/VERSION b/VERSION
index 31bee6a..b94725e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.0.380
+1.0.381
diff --git a/gf180mcu/Makefile.in b/gf180mcu/Makefile.in
index be9cf7b..77161b0 100644
--- a/gf180mcu/Makefile.in
+++ b/gf180mcu/Makefile.in
@@ -159,6 +159,12 @@
 
 USE_REFERENCE = @USE_REFERENCE@
 
+ifeq (${USE_REFERENCE}, 1)
+    REFERENCE_JSON = ${TECH}.json
+else
+    REFERENCE_JSON =
+endif
+
 # Path to GF180MCU library sources
 PDK_URL = https://github.com/google
 OSU_URL = https://github.com/stineje
@@ -246,6 +252,11 @@
 else
     COMMIT_DEFS += -DFD_IP_SRAM_COMMIT=$(shell cd ${GF180MCU_SRAM_PATH} ; git rev-parse HEAD)
 endif
+ifeq (${GF180MCU_OSU_SC_PATH},)
+    COMMIT_DEFS += -DOSU_SC_COMMIT="unknown"
+else
+    COMMIT_DEFS += -DOSU_SC_COMMIT=$(shell cd ${GF180MCU_OSU_SC_PATH} ; git rev-parse HEAD)
+endif
 
 COMMIT_DEFS += -DMAGIC_COMMIT=$(shell magic -dnull -noconsole --commit)
 COMMIT_DEFS += -DMAGIC_VERSION=$(shell magic -dnull -noconsole --version)
@@ -444,62 +455,80 @@
 prerequisites: pr-repo io-repo sc-7t-repo sc-9t-repo sram-repo osu-sc-repo
 
 pr-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		FD_PR_COMMIT = `cat ${REFERENCE_JSON} | grep gf180mcu_fd_pr | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${GF180MCU_PR_PATH}" != "x" ; then \
 		if test -d "${GF180MCU_PR_PATH}" ; then \
 			echo "Using existing installation of primitive library from ${GF180MCU_PR_PATH}" ; \
 		else \
 			echo "Downloading primitive library from ${GF180MCU_PR_PATH}" ; \
-			../scripts/download.sh ${PDK_LIB_PR} ${GF180MCU_PR_PATH} ; \
+			../scripts/download.sh ${PDK_LIB_PR} ${GF180MCU_PR_PATH} ${FD_PR_COMMIT}; \
 		fi ; \
 	fi
 
 io-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		FD_IO_COMMIT = `cat ${REFERENCE_JSON} | grep gf180mcu_fd_io | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${GF180MCU_IO_PATH}" != "x" ; then \
 		if test -d "${GF180MCU_IO_PATH}" ; then \
 			echo "Using existing installation of I/O library from ${GF180MCU_IO_PATH}" ; \
 		else \
 			echo "Downloading I/O library from ${GF180MCU_IO_PATH}" ; \
-			../scripts/download.sh ${PDK_LIB_IO} ${GF180MCU_IO_PATH} ; \
+			../scripts/download.sh ${PDK_LIB_IO} ${GF180MCU_IO_PATH} ${FD_IO_COMMIT}; \
 		fi ; \
 	fi
 
 sc-7t-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		FD_SC_MCU7T5V0_COMMIT = `cat ${REFERENCE_JSON} | grep gf180mcu_fd_sc_mcu7t5v0 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${GF180MCU_SC_7T5V0_PATH}" != "x" ; then \
 		if test -d "${GF180MCU_SC_7T5V0_PATH}" ; then \
 			echo "Using existing installation of 7-track standard cell library from ${GF180MCU_SC_7T5V0_PATH}" ; \
 		else \
 			echo "Downloading 7-track standard cell library from ${GF180MCU_SC_7T5V0_PATH}" ; \
-			../scripts/download.sh ${PDK_LIB_SC_7T5V0} ${GF180MCU_SC_7T5V0_PATH} ; \
+			../scripts/download.sh ${PDK_LIB_SC_7T5V0} ${GF180MCU_SC_7T5V0_PATH} ${FD_SC_MCU7T5V0_COMMIT}; \
 		fi ; \
 	fi
 
 sc-9t-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		FD_SC_MCU9T5V0_COMMIT = `cat ${REFERENCE_JSON} | grep gf180mcu_fd_sc_mcu9t5v0 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${GF180MCU_SC_9T5V0_PATH}" != "x" ; then \
 		if test -d "${GF180MCU_SC_9T5V0_PATH}" ; then \
 			echo "Using existing installation of 9-track standard cell library from ${GF180MCU_SC_9T5V0_PATH}" ; \
 		else \
 			echo "Downloading 9-track standard cell library from ${GF180MCU_SC_9T5V0_PATH}" ; \
-			../scripts/download.sh ${PDK_LIB_SC_9T5V0} ${GF180MCU_SC_9T5V0_PATH} ; \
+			../scripts/download.sh ${PDK_LIB_SC_9T5V0} ${GF180MCU_SC_9T5V0_PATH} ${FD_SC_MCU9T5V0_COMMIT}; \
 		fi ; \
 	fi
 
 sram-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		FD_IP_SRAM_COMMIT = `cat ${REFERENCE_JSON} | grep gf180mcu_fd_ip_sram | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${GF180MCU_SRAM_PATH}" != "x" ; then \
 		if test -d "${GF180MCU_SRAM_PATH}" ; then \
 			echo "Using existing installation of primitive library from ${GF180MCU_SRAM_PATH}" ; \
 		else \
 			echo "Downloading primitive library from ${GF180MCU_SRAM_PATH}" ; \
-			../scripts/download.sh ${PDK_LIB_SRAM} ${GF180MCU_SRAM_PATH} ; \
+			../scripts/download.sh ${PDK_LIB_SRAM} ${GF180MCU_SRAM_PATH} ${FD_IP_SRAM_COMMIT}; \
 		fi ; \
 	fi
 
 osu-sc-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		OSU_SC_COMMIT = `cat ${REFERENCE_JSON} | grep gf180mcu_osu_sc_gf12t3v3 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${GF180MCU_OSU_SC_PATH}" != "x" ; then \
 		if test -d "${GF180MCU_OSU_SC_PATH}" ; then \
 			echo "Using existing installation of OSU 3.3V standard cell library from ${GF180MCU_OSU_SC_PATH}" ; \
 		else \
 			echo "Downloading OSU 3.3V standard cell library from ${GF180MCU_OSU_SC_PATH}" ; \
-			../scripts/download.sh ${PDK_LIB_OSU_SC} ${GF180MCU_OSU_SC_PATH} ; \
+			../scripts/download.sh ${PDK_LIB_OSU_SC} ${GF180MCU_OSU_SC_PATH} ${OSU_SC_COMMIT} ; \
 		fi ; \
 	fi
 
diff --git a/gf180mcu/gf180mcu.json b/gf180mcu/gf180mcu.json
index fc14e28..46d3eef 100644
--- a/gf180mcu/gf180mcu.json
+++ b/gf180mcu/gf180mcu.json
@@ -64,7 +64,9 @@
     ],
     "stdcells": {
         "gf180mcu_fd_sc_mcu9t5v0": "FD_SC_MCU9T5V0_COMMIT",
-        "gf180mcu_fd_sc_mcu7t5v0": "FD_SC_MCU7T5V0_COMMIT"
+        "gf180mcu_fd_sc_mcu7t5v0": "FD_SC_MCU7T5V0_COMMIT",
+	"gf180mcu_osu_sc_gf12t3v3": "OSU_SC_COMMIT",
+	"gf180mcu_osu_sc_gf9t3v3": "OSU_SC_COMMIT"
     },
     "iocells": {
         "gf180mcu_fd_io": "FD_IO_COMMIT"
@@ -91,6 +93,8 @@
         "gf180mcu_fd_io": "2aeec51ea2824b6cc0b396acfc39f4535f40b23a",
         "gf180mcu_fd_sc_mcu7t5v0": "8743b6f9641eb8707179c4e51703380d4dc90f16",
         "gf180mcu_fd_sc_mcu9t5v0": "376ea56fa36ce7702595ce4e0e3c9357ee38c81c",
-        "gf180mcu_fd_ip_sram": "9c411928870ce15226228fa52ddb6ecc0ea4ffbe"
+        "gf180mcu_fd_ip_sram": "9c411928870ce15226228fa52ddb6ecc0ea4ffbe",
+	"gf180mcu_osu_sc_gf12t3v3": "e16f26cda99e81e004d7141fc815e67b66f971c2",
+	"gf180mcu_osu_sc_gf9t3v3": "e16f26cda99e81e004d7141fc815e67b66f971c2"
     }
 }
diff --git a/scripts/.gitignore b/scripts/.gitignore
index 1383243..17b7c2f 100644
--- a/scripts/.gitignore
+++ b/scripts/.gitignore
@@ -4,4 +4,5 @@
 !configure.ac
 !tools.txt
 !print_tools_make.pl
-!download.sh
\ No newline at end of file
+!download.sh
+!update.sh
diff --git a/scripts/configure b/scripts/configure
index 8e58b0c..1c5c461 100755
--- a/scripts/configure
+++ b/scripts/configure
@@ -3338,6 +3338,8 @@
         pdks_reference=$withval
         if test "$withval" == "yes" -o "$withval" == "YES"; then
             USE_REFERENCE=1
+	else
+            USE_REFERENCE="$pdks_reference"
         fi
 
 fi
diff --git a/scripts/configure.ac b/scripts/configure.ac
index 44055f2..216b520 100755
--- a/scripts/configure.ac
+++ b/scripts/configure.ac
@@ -284,6 +284,8 @@
         pdks_reference=$withval
         if test "$withval" == "yes" -o "$withval" == "YES"; then
             USE_REFERENCE=1
+	else
+            USE_REFERENCE="$pdks_reference"
         fi
     ],
 )
diff --git a/scripts/download.sh b/scripts/download.sh
index 660c978..f25eb2d 100755
--- a/scripts/download.sh
+++ b/scripts/download.sh
@@ -71,9 +71,13 @@
     if type "git" > /dev/null; then
         echo "Cloning $1 to $2"
     	if [ $# -gt 2 ]; then
-            # git clone $1 $2
-	    # git checkout $3
-	    git clone --branch $3 --single-branch $1 $2
+	    if [ "$3" == "unknown" ]; then
+            	git clone --depth 1 $1 $2
+	    else
+		# git clone $1 $2
+		# git checkout $3
+		git clone --branch $3 --single-branch $1 $2
+	    fi
 	else
             git clone --depth 1 $1 $2
     	fi
diff --git a/scripts/update.sh b/scripts/update.sh
new file mode 100755
index 0000000..41cdaad
--- /dev/null
+++ b/scripts/update.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+#
+# update.sh --
+#	Update a package in sources/.  If the package is a git
+#	repository, then do a git pull.  (Use download.sh for
+#	tarballs.)
+#
+#	Usage:  update.sh <target_dir>
+#
+# where:
+#
+#	<target_dir> is the local name of a git repository directory.
+#
+
+set -e
+
+if type "git" > /dev/null; then
+    echo "Pulling $1 into $2"
+    cd $2
+    git pull
+
+else
+    echo "ERROR: \"git\" is required to automatically update repositories."
+    exit 1
+fi
+
+exit 0
+
diff --git a/sky130/Makefile.in b/sky130/Makefile.in
index a61d8fd..ab9cec6 100644
--- a/sky130/Makefile.in
+++ b/sky130/Makefile.in
@@ -254,6 +254,12 @@
 
 USE_REFERENCE = @USE_REFERENCE@
 
+ifeq (${USE_REFERENCE}, 1)
+    REFERENCE_JSON = ${TECH}.json
+else
+    REFERENCE_JSON =
+endif
+
 # NOTE:  Install destination is the git repository of the technology platform.
 # Once updated in git, the git project can be distributed to all hosts.
 #
@@ -300,6 +306,11 @@
     COMMIT_DEFS = -DOPEN_PDKS_COMMIT=${OPEN_PDKS_COMMIT}
 endif
 
+ifeq (${SKYWATER_PATH},)
+    COMMIT_DEFS += -DSKYWATER_COMMIT="unknown"
+else
+    COMMIT_DEFS += -DSKYWATER_COMMIT=$(shell cd ${SKYWATER_PATH} ; git rev-parse HEAD)
+endif
 ifeq (${XSCHEM_PATH},)
     COMMIT_DEFS += -DXSCHEM_COMMIT="unknown"
 else
@@ -617,102 +628,132 @@
 prerequisites: pdk-repo alpha-repo xschem-repo klayout-repo precheck-repo sram-repo sram-space-repo osu-t12-repo osu-t15-repo osu-t18-repo
 
 pdk-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		SKYWATER_COMMIT = `cat ${REFERENCE_JSON} | grep skywater_pdk | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${SKYWATER_PATH}" != "x" ; then \
 		if test -d "${SKYWATER_PATH}" ; then \
 			echo "Using existing installation of SkyWater PDK from ${SKYWATER_PATH}" ; \
 		else \
 			echo "Downloading SkyWater PDK from ${PDK_URL}" ; \
-			custom/scripts/pdk_download.sh ${PDK_URL} ${SKYWATER_PATH} ; \
+			custom/scripts/pdk_download.sh ${PDK_URL} ${SKYWATER_PATH} ${SKYWATER_COMMIT} ; \
 		fi ; \
 	fi
 
 alpha-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		ALPHA_COMMIT = `cat ${REFERENCE_JSON} | grep sky130_ml_xx_hd | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${ALPHA_PATH}" != "x" ; then \
 		if test -d "${ALPHA_PATH}" ; then \
 			echo "Using existing installation of alphanumeric library from ${ALPHA_PATH}" ; \
 		else \
 			echo "Downloading alphanumeric library from ${ALPHA_URL}" ; \
-			../scripts/download.sh ${ALPHA_URL} ${ALPHA_PATH} ; \
+			../scripts/download.sh ${ALPHA_URL} ${ALPHA_PATH} ${ALPHA_COMMIT} ; \
 		fi ; \
 	fi
 
 sram-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		SRAM_COMMIT = `cat ${REFERENCE_JSON} | grep sky130_sram_macros | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${SRAM_PATH}" != "x" ; then \
 		if test -d "${SRAM_PATH}" ; then \
 			echo "Using existing installation of SRAM macro library from ${SRAM_PATH}" ; \
 		else \
 			echo "Downloading SRAM macro library from ${SRAM_URL}" ; \
-			../scripts/download.sh ${SRAM_URL} ${SRAM_PATH} ; \
+			../scripts/download.sh ${SRAM_URL} ${SRAM_PATH} ${SRAM_COMMIT}; \
 		fi ; \
 	fi
 
 sram-space-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		SRAM_SPACE_COMMIT = `cat ${REFERENCE_JSON} | grep sky130_fd_bd_sram | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${SRAM_SPACE_PATH}" != "x" ; then \
 		if test -d "${SRAM_SPACE_PATH}" ; then \
 			echo "Using existing installation of SRAM build-space library from ${SRAM_SPACE_PATH}" ; \
 		else \
 			echo "Downloading SRAM build-space library from ${SRAM_SPACE_URL}" ; \
-			../scripts/download.sh ${SRAM_SPACE_URL} ${SRAM_SPACE_PATH} ; \
+			../scripts/download.sh ${SRAM_SPACE_URL} ${SRAM_SPACE_PATH} ${SRAM_SPACE_COMMIT} ; \
 		fi ; \
 	fi
 
 xschem-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		XSCHEM_COMMIT = `cat ${REFERENCE_JSON} | grep xschem_sky130 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${XSCHEM_PATH}" != "x" ; then \
 		if test -d "${XSCHEM_PATH}" ; then \
 			echo "Using existing installation of xschem setup from ${XSCHEM_PATH}" ; \
 		else \
 			echo "Downloading xschem setup from ${XSCHEM_URL}" ; \
-			../scripts/download.sh ${XSCHEM_URL} ${XSCHEM_PATH} ; \
+			../scripts/download.sh ${XSCHEM_URL} ${XSCHEM_PATH} ${XSCHEM_COMMIT} ; \
 		fi ; \
 	fi
 
 klayout-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		KLAYOUT_COMMIT = `cat ${REFERENCE_JSON} | grep klayout_sky130 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${KLAYOUT_PATH}" != "x" ; then \
 		if test -d "${KLAYOUT_PATH}" ; then \
 			echo "Using existing installation of klayout setup from ${KLAYOUT_PATH}" ; \
 		else \
 			echo "Downloading klayout setup from ${KLAYOUT_URL}" ; \
-			../scripts/download.sh ${KLAYOUT_URL} ${KLAYOUT_PATH} ; \
+			../scripts/download.sh ${KLAYOUT_URL} ${KLAYOUT_PATH} ${KLAYOUT_COMMIT} ; \
 		fi ; \
 	fi
 
 precheck-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		PRECHECK_COMMIT = `cat ${REFERENCE_JSON} | grep precheck_sky130 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${PRECHECK_PATH}" != "x" ; then \
 		if test -d "${PRECHECK_PATH}" ; then \
 			echo "Using existing installation of klayout setup from ${PRECHECK_PATH}" ; \
 		else \
 			echo "Downloading klayout setup from ${PRECHECK_URL}" ; \
-			../scripts/download.sh ${PRECHECK_URL} ${PRECHECK_PATH} ; \
+			../scripts/download.sh ${PRECHECK_URL} ${PRECHECK_PATH} ${PRECHECK_COMMIT} ; \
 		fi ; \
 	fi
 
 osu-t12-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		OSU_T12_COMMIT = `cat ${REFERENCE_JSON} | grep sky130_osu_sc_t12 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${OSU_T12_PATH}" != "x" ; then \
 		if test -d "${OSU_T12_PATH}" ; then \
 			echo "Using existing installation of OSU T12 standard cell library from ${OSU_T12_PATH}" ; \
 		else \
 			echo "Downloading OSU standard T12 cell library from ${OSU_T12_URL}" ; \
-			../scripts/download.sh ${OSU_T12_URL} ${OSU_T12_PATH} 0 ; \
+			../scripts/download.sh ${OSU_T12_URL} ${OSU_T12_PATH} ${OSU_T12_COMMIT} ; \
 		fi ; \
 	fi
 
 osu-t15-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		OSU_T15_COMMIT = `cat ${REFERENCE_JSON} | grep sky130_osu_sc_t15 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${OSU_T15_PATH}" != "x" ; then \
 		if test -d "${OSU_T15_PATH}" ; then \
 			echo "Using existing installation of OSU T15 standard cell library from ${OSU_T15_PATH}" ; \
 		else \
 			echo "Downloading OSU standard T15 cell library from ${OSU_T15_URL}" ; \
-			../scripts/download.sh ${OSU_T15_URL} ${OSU_T15_PATH} 0 ; \
+			../scripts/download.sh ${OSU_T15_URL} ${OSU_T15_PATH} ${OSU_T15_COMMIT} ; \
 		fi ; \
 	fi
 
 osu-t18-repo:
+	if test "x${REFERENCE_JSON}" != "x"; then \
+		OSU_T18_COMMIT = `cat ${REFERENCE_JSON} | grep sky130_osu_sc_t18 | grep -v COMMIT | cut -d'"' -f4` ; \
+	fi
 	if test "x${OSU_T18_PATH}" != "x" ; then \
 		if test -d "${OSU_T18_PATH}" ; then \
 			echo "Using existing installation of OSU T18 standard cell library from ${OSU_T18_PATH}" ; \
 		else \
 			echo "Downloading OSU standard T18 cell library from ${OSU_T18_URL}" ; \
-			../scripts/download.sh ${OSU_T18_URL} ${OSU_T18_PATH} 0 ; \
+			../scripts/download.sh ${OSU_T18_URL} ${OSU_T18_PATH} ${OSU_T18_COMMIT} ; \
 		fi ; \
 	fi
 
diff --git a/sky130/custom/scripts/pdk_download.sh b/sky130/custom/scripts/pdk_download.sh
index a8e8804..fba1a9f 100755
--- a/sky130/custom/scripts/pdk_download.sh
+++ b/sky130/custom/scripts/pdk_download.sh
@@ -5,7 +5,7 @@
 #	Download and install a PDK from git
 # 	(mainly for use with the Google/SkyWater SKY130 PDK)
 #
-#  Usage:	pdk_download.sh <url> <destination>
+#  Usage:	pdk_download.sh <url> <destination> [<commit>|<tag>]
 #
 
 pdir=`dirname $2`
@@ -15,7 +15,15 @@
 # Clone repository
 
 echo "Cloning PDK repository"
-git clone $1 $2
+if [ $# -gt 2 ]; then
+    if [ "$3" == "unknown" ]; then
+    	git clone $1 $2
+    else
+	git clone --branch $3 --single-branch $1 $2
+    fi
+else
+    git clone $1 $2
+fi
 
 # Get submodules
 
diff --git a/sky130/sky130.json b/sky130/sky130.json
index 194f7df..febb75c 100644
--- a/sky130/sky130.json
+++ b/sky130/sky130.json
@@ -79,6 +79,7 @@
         "sky130_fd_bd_sram": "SRAM_BUILD_COMMIT"
     },
     "other": {
+        "skywater_pdk": "SKYWATER_COMMIT",
         "sky130_ml_xx_hd": "ALPHA_COMMIT",
         "xschem_sky130": "XSCHEM_COMMIT",
         "klayout_sky130": "KLAYOUT_COMMIT",
@@ -100,6 +101,7 @@
         "sky130_osu_sc_t15": "95d1c19abb47e1b2945847acb4e817b1b8417c43",
         "sky130_osu_sc_t18": "aa2b509f3c8f32ea94fdb55ac9768754667c1658",
         "sky130_sram_macros": "c2333394e0b0b9d9d71185678a8d8087715d5e3b",
+        "sky130_fd_bd_sram": "be33adbcf188fdeab5c061699847d9d440f7a084",
         "sky130_ml_xx_hd": "6eb3b0718552b034f1bf1870285ff135e3fb2dcb",
         "xschem_sky130": "5fa1b2e30eda4cdc9949a989d7482531a30b56d4",
         "klayout_sky130": "7cd7d32bdcbbe32f456a73a02e4653983a6a1850",