diff --git a/6502/C64/disks/empty.d64 b/6502/C64/disks/empty.d64
new file mode 100644
index 0000000..b598b37
Binary files /dev/null and b/6502/C64/disks/empty.d64 differ
diff --git a/6502/C64/emulator/build-devenv.sh b/6502/C64/emulator/build-devenv.sh
index aec0986..cd034ab 100755
--- a/6502/C64/emulator/build-devenv.sh
+++ b/6502/C64/emulator/build-devenv.sh
@@ -13,4 +13,5 @@ rm -f "${basedir}/cbmfiles/devenv"
 keybuf="2 drive 19 load\n47 load\n1 drive 26 load\n3 drive 10 load\n\
 savesystem devenv\ndos s0:notdone\n"
 
-"${emulatordir}/run-in-vice.sh" "c64-volksforth83" "${keybuf}"
+DISK9=vforth4_1 DISK10=vforth4_3 DISK11=file-words \
+  "${emulatordir}/run-in-vice.sh" "c64-volksforth83" "${keybuf}"
diff --git a/6502/C64/emulator/build-testbase.sh b/6502/C64/emulator/build-testbase.sh
index 6f846e0..a53cb4b 100755
--- a/6502/C64/emulator/build-testbase.sh
+++ b/6502/C64/emulator/build-testbase.sh
@@ -6,10 +6,11 @@ basedir="$(realpath --relative-to="$PWD" "${emulatordir}/..")"
 
 rm -f "${basedir}/cbmfiles/testbase"
 
-# load savesystem w/o editor from file-words.d64 block 20 in drive 11.
-# load include and dos from file-words.d64 block 10 in drive 11.
+# load savesystem w/o editor from file-words.d64 block 20.
+# load include and dos from file-words.d64 block 10.
 # savesystem and then scratch file notdone to exit emulator.
 keybuf="3 drive 20 load\n3 drive 10 load\n\
 savesystem testbase\ndos s0:notdone\n"
 
-"${emulatordir}/run-in-vice.sh" "c64-volksforth83" "${keybuf}"
+DISK11=file-words "${emulatordir}/run-in-vice.sh" \
+  "c64-volksforth83" "${keybuf}"
diff --git a/6502/C64/emulator/build-testbase16.sh b/6502/C64/emulator/build-testbase16.sh
index 5918d95..bbf3660 100755
--- a/6502/C64/emulator/build-testbase16.sh
+++ b/6502/C64/emulator/build-testbase16.sh
@@ -6,11 +6,11 @@ basedir="$(realpath --relative-to="$PWD" "${emulatordir}/..")"
 
 rm -f "${basedir}/cbmfiles/testbase"
 
-# load savesystem w/o editor from file-words.d64 block 20 in drive 11.
-# load include and dos from file-words.d64 block 10 in drive 11.
+# load savesystem w/o editor from file-words.d64 block 20.
+# load include and dos from file-words.d64 block 10.
 # savesystem and then scratch file notdone to exit emulator.
 keybuf="3 drive 20 load\n3 drive 10 load\n\
 savesystem testbase16\ndos s0:notdone\n"
 
-VICE=xplus4 "${emulatordir}/run-in-vice.sh" \
+VICE=xplus4 DISK11=file-words "${emulatordir}/run-in-vice.sh" \
   "c16-volksforth83" "${keybuf}"
diff --git a/6502/C64/emulator/run-in-vice.sh b/6502/C64/emulator/run-in-vice.sh
index 09a05d5..6ef9ee8 100755
--- a/6502/C64/emulator/run-in-vice.sh
+++ b/6502/C64/emulator/run-in-vice.sh
@@ -2,6 +2,9 @@
 set -e
 
 test -n "$VICE" || VICE=x64
+test -n "$DISK9" || DISK9=empty
+test -n "$DISK10" || DISK10=empty
+test -n "$DISK11" || DISK11=empty
 emulatordir="$(realpath --relative-to="$PWD" "$(dirname "${BASH_SOURCE[0]}")")"
 basedir="$(realpath --relative-to="$PWD" "${emulatordir}/..")"
 
@@ -29,9 +32,9 @@ fi
   -drive10type 1541 \
   -drive11type 1541 \
   -fs8 "${basedir}/cbmfiles" \
-  -9 "${basedir}/disks/vforth4_1.d64" \
-  -10 "${basedir}/disks/vforth4_3.d64" \
-  -11 "${basedir}/disks/file-words.d64" \
+  -9 "${basedir}/disks/${DISK9}.d64" \
+  -10 "${basedir}/disks/${DISK10}.d64" \
+  -11 "${basedir}/disks/${DISK11}.d64" \
   -symkeymap "${emulatordir}/x11_sym_vf_de.vkm" \
   -keymap 2 \
   $autostart \