diff --git a/PDP10/kx10_dpy.c b/PDP10/kx10_dpy.c
index 58f0beb..1db3ae9 100644
--- a/PDP10/kx10_dpy.c
+++ b/PDP10/kx10_dpy.c
@@ -454,37 +454,63 @@ cpu_set_switches(unsigned long w1, unsigned long w2) {
 #if NUM_DEVS_WCNSLS > 0
 #define WCNSLS_DEVNUM 0420
 
-#define UNIT_JOY      (1 << DEV_V_UF)
+#define UNIT_JOY      (1 << DEV_V_UF)      /* Use USB gaming devices. */
+#define UNIT_CSCOPE   (1 << (DEV_V_UF+1))  /* Enable color scope. */
 
 t_stat wcnsls_devio(uint32 dev, uint64 *data);
+t_stat wcnsls_svc (UNIT *uptr);
+t_stat wcnsls_reset (DEVICE *dptr);
 const char *wcnsls_description (DEVICE *dptr);
 
+static uint64 dev420_cono = 0;
+static uint8 cscope_r = 0;
+static uint8 cscope_g = 0;
+static uint8 cscope_b = 0;
+static VID_DISPLAY *cscope_display = NULL;
+static uint32 fade[512 * 512];
+static uint32 dot[7 * 7];
+
 DIB wcnsls_dib[] = {
     { WCNSLS_DEVNUM, 1, &wcnsls_devio, NULL }};
 
 MTAB wcnsls_mod[] = {
     { UNIT_JOY, UNIT_JOY, "JOYSTICK", "JOYSTICK", NULL, NULL, NULL,
       "Use USB joysticks"},
+    { UNIT_CSCOPE, UNIT_CSCOPE, "CSCOPE", "CSCOPE", NULL, NULL, NULL,
+      "Enable color scope"},
     { 0 }
     };
 
 UNIT wcnsls_unit[] = {
-    { UDATA (NULL, UNIT_IDLE, 0) }};
+    { UDATA (wcnsls_svc, UNIT_IDLE, 0) }};
+
+REG wcnsls_reg[] = {
+    {ORDATA(CONO, dev420_cono, 18)},
+    {0}
+};
 
 DEVICE wcnsls_dev = {
-    "WCNSLS", wcnsls_unit, NULL, wcnsls_mod,
+    "WCNSLS", wcnsls_unit, wcnsls_reg, wcnsls_mod,
     NUM_DEVS_WCNSLS, 0, 0, 0, 0, 0,
+    NULL, NULL, wcnsls_reset,
     NULL, NULL, NULL,
-    NULL, NULL, NULL,
-    &wcnsls_dib, DEV_DISABLE | DEV_DIS | DEV_DEBUG, 0, NULL,
+    &wcnsls_dib, DEV_DISABLE | DEV_DIS | DEV_DEBUG, 0, dev_debug,
     NULL, NULL, NULL, NULL, NULL, &wcnsls_description
     };
 
 const char *wcnsls_description (DEVICE *dptr)
 {
-    return "MIT Spacewar Consoles";
+    return "MIT Spacewar Consoles, and DEC color scope";
 }
 
+/* Device 420 CONO bits. */
+#define CONO_BLUE    0000020  /* Color scope blue enable */
+#define CONO_SPCWAR  0000040  /* Spacewar consoles */
+#define CONO_GREEN   0002000  /* Color scope green enable */
+#define CONO_RANDOM  0004000  /* Random switches */
+#define CONO_RED     0200000  /* Color scope red enable */
+#define CONO_KNIGHT  0400000  /* Switches in TK's office */
+
 /*
  * map 32-bit "spacewar_switches" value to what PDP-6/10 game expects
  * (four 9-bit bytes)
@@ -512,55 +538,86 @@ const char *wcnsls_description (DEVICE *dptr)
 #define BUT2       (JOY_MAX_BUTTONS*2)
 #define BUT3       (JOY_MAX_BUTTONS*3)
 
+static void
+cscope_init (void)
+{
+    int i;
+    fade[0] = vid_map_rgba_window (cscope_display, 0, 0, 0, 240);
+    for (i = 1; i < 512 * 512; i++)
+        fade[i] = fade[0];
+}
+
+static void
+cscope_plot(int x, int y)
+{
+    int i, j;
+    for (i = 0; i < 7; i++) {
+      	 for (j = 0; j < 7; j++) {
+	     int dx = i - 3, dy = j - 3;
+	     int r2 = dx*dx + dy*dy;
+	     double focus = 0.2;
+	     double intensity = 0xFF/15.0;
+	     double alpha = 0xFF*exp(-focus*r2);
+	     dot[i + 7*j] = vid_map_rgba_window (cscope_display,
+						 (uint8)(intensity*(cscope_r << 4)),
+						 (uint8)(intensity*(cscope_g << 4)),
+						 (uint8)(intensity*(cscope_b << 4)),
+						 (uint8)alpha);
+	 }
+    }
+
+    vid_draw_window (cscope_display, x - 3, 511 - y - 3, 7, 7, dot);
+}
+
 static uint64 joystick_switches (void)
 {
-  uint64 switches = 0777777777777LL;
+    uint64 switches = 0777777777777LL;
 
-  if (joy_axes[JOY0] > JOY_TRIG)
-    switches &= ~(CCW << UR);
-  else if (joy_axes[JOY0] < -JOY_TRIG)
-    switches &= ~(CW << UR);
-  if (joy_axes[JOY0+1] < -JOY_TRIG)
-    switches &= ~(THRUST << UR);
-  if (joy_buttons[BUT0])
-    switches &= ~(FIRE << UR);
-  if (joy_buttons[BUT0+1])
-    switches &= ~(HYPER << UR);
+    if (joy_axes[JOY0] > JOY_TRIG)
+        switches &= ~(CCW << UR);
+    else if (joy_axes[JOY0] < -JOY_TRIG)
+        switches &= ~(CW << UR);
+    if (joy_axes[JOY0+1] < -JOY_TRIG)
+        switches &= ~(THRUST << UR);
+    if (joy_buttons[BUT0])
+        switches &= ~(FIRE << UR);
+    if (joy_buttons[BUT0+1])
+        switches &= ~(HYPER << UR);
 
-  if (joy_axes[JOY1] > JOY_TRIG)
-    switches &= ~(CCW << LR);
-  else if (joy_axes[JOY1] < -JOY_TRIG)
-    switches &= ~(CW << LR);
-  if (joy_axes[JOY1+1] < -JOY_TRIG)
-    switches &= ~(THRUST << LR);
-  if (joy_buttons[BUT1])
-    switches &= ~(FIRE << LR);
-  if (joy_buttons[BUT1+1])
-    switches &= ~(HYPER << LR);
+    if (joy_axes[JOY1] > JOY_TRIG)
+        switches &= ~(CCW << LR);
+    else if (joy_axes[JOY1] < -JOY_TRIG)
+        switches &= ~(CW << LR);
+    if (joy_axes[JOY1+1] < -JOY_TRIG)
+        switches &= ~(THRUST << LR);
+    if (joy_buttons[BUT1])
+        switches &= ~(FIRE << LR);
+    if (joy_buttons[BUT1+1])
+        switches &= ~(HYPER << LR);
 
-  if (joy_axes[JOY2] > JOY_TRIG)
-    switches &= ~(CCW << LL);
-  else if (joy_axes[JOY2] < -JOY_TRIG)
-    switches &= ~(CW << LL);
-  if (joy_axes[JOY2+1] < -JOY_TRIG)
-    switches &= ~(THRUST << LL);
-  if (joy_buttons[BUT2])
-    switches &= ~(FIRE << LL);
-  if (joy_buttons[BUT2+1])
-    switches &= ~(HYPER << LL);
+    if (joy_axes[JOY2] > JOY_TRIG)
+        switches &= ~(CCW << LL);
+    else if (joy_axes[JOY2] < -JOY_TRIG)
+        switches &= ~(CW << LL);
+    if (joy_axes[JOY2+1] < -JOY_TRIG)
+        switches &= ~(THRUST << LL);
+    if (joy_buttons[BUT2])
+        switches &= ~(FIRE << LL);
+    if (joy_buttons[BUT2+1])
+        switches &= ~(HYPER << LL);
 
-  if (joy_axes[JOY3] > JOY_TRIG)
-    switches &= ~((uint64)CCW << UL);
-  else if (joy_axes[JOY3] < -JOY_TRIG)
-    switches &= ~((uint64)CW << UL);
-  if (joy_axes[JOY3+1] < -JOY_TRIG)
-    switches &= ~((uint64)THRUST << UL);
-  if (joy_buttons[BUT3])
-    switches &= ~((uint64)FIRE << UL);
-  if (joy_buttons[BUT3+1])
-    switches &= ~(HYPER << UL);
+    if (joy_axes[JOY3] > JOY_TRIG)
+        switches &= ~((uint64)CCW << UL);
+    else if (joy_axes[JOY3] < -JOY_TRIG)
+        switches &= ~((uint64)CW << UL);
+    if (joy_axes[JOY3+1] < -JOY_TRIG)
+        switches &= ~((uint64)THRUST << UL);
+    if (joy_buttons[BUT3])
+        switches &= ~((uint64)FIRE << UL);
+    if (joy_buttons[BUT3+1])
+        switches &= ~(HYPER << UL);
 
-  return switches;
+    return switches;
 }
 
 static uint64 keyboard_switches (void)
@@ -589,17 +646,66 @@ static uint64 keyboard_switches (void)
     return switches;
 }
 
+t_stat wcnsls_svc (UNIT *uptr)
+{
+    vid_refresh_window (cscope_display);
+    vid_draw_window (cscope_display, 0, 0, 512, 512, fade);
+    sim_activate_after (uptr, 33333);
+    return SCPE_OK;
+}
+
+t_stat
+wcnsls_reset (DEVICE *dptr)
+{
+    t_stat r;
+    if (sim_switches & SWMASK('P') || dptr->flags & DEV_DIS ||
+	(wcnsls_unit->flags & UNIT_CSCOPE) == 0) {
+        sim_cancel (wcnsls_unit);
+	if (cscope_display != NULL)
+	    vid_close_window (cscope_display);
+	cscope_display = NULL;
+    } else if (cscope_display == NULL) {
+        r = vid_open_window (&cscope_display, dptr, "Color scope", 512, 512, 0);
+	if (r != SCPE_OK)
+	    return r;
+	/* Allow time for window to open and data structures to settle. */
+        sim_os_sleep (1);
+	r = vid_set_alpha_mode (cscope_display, SIM_ALPHA_BLEND);
+	if (r != SCPE_OK)
+	    return r;
+	sim_activate_abs (wcnsls_unit, 0);
+	cscope_init ();
+    }
+    return SCPE_OK;
+}
+
 t_stat wcnsls_devio(uint32 dev, uint64 *data) {
     switch (dev & 3) {
     case CONO:
         /* CONO WCNSLS,40       ;enable spacewar consoles */
+        sim_debug (DEBUG_CONO, &wcnsls_dev, "%06llo\n", *data);
+        dev420_cono = *data;
+        if (dev420_cono & CONO_RED)
+          cscope_r = (dev420_cono >> 12) & 017;
+        if (dev420_cono & CONO_GREEN)
+          cscope_g = (dev420_cono >> 6) & 017;
+        if (dev420_cono & CONO_BLUE)
+          cscope_b = dev420_cono & 017;
+        break;
+
+    case DATAO:
+        sim_debug (DEBUG_DATAIO, &wcnsls_dev, "DATAO %012llo\n", *data);
+        if (wcnsls_unit->flags & UNIT_CSCOPE)
+            cscope_plot((*data >> 9) & 0777, *data & 0777);
         break;
 
     case DATAI:
-        if (wcnsls_unit->flags & UNIT_JOY) {
-          *data = joystick_switches ();
-        } else {
-          *data = keyboard_switches ();
+        if (dev420_cono & CONO_SPCWAR) {
+          if (wcnsls_unit->flags & UNIT_JOY) {
+            *data = joystick_switches ();
+          } else {
+            *data = keyboard_switches ();
+          }
         }
 
         sim_debug(DEBUG_DATAIO, &wcnsls_dev, "WCNSLS %03o DATI %012llo PC=%06o\n",
@@ -648,39 +754,39 @@ const char *ocnsls_description (DEVICE *dptr)
 
 static uint64 old_switches (void)
 {
-  uint64 switches = 0;
+    uint64 switches = 0;
 
-  if (joy_axes[JOY0] > JOY_TRIG)
-    switches |= OCCW;
-  else if (joy_axes[JOY0] < -JOY_TRIG)
-    switches |= OCW;
-  if (joy_axes[JOY0+1] < -JOY_TRIG)
-    switches |= FAST;
-  if (joy_axes[JOY0+1] > JOY_TRIG)
-    switches |= SLOW;
-  if (joy_buttons[BUT0])
-    switches |= OFIRE;
-  if (joy_buttons[BUT0+1])
-    switches |= OHYPER;
-  if (joy_buttons[BUT0+2])
-    switches |= BEACON;
+    if (joy_axes[JOY0] > JOY_TRIG)
+        switches |= OCCW;
+    else if (joy_axes[JOY0] < -JOY_TRIG)
+        switches |= OCW;
+    if (joy_axes[JOY0+1] < -JOY_TRIG)
+        switches |= FAST;
+    if (joy_axes[JOY0+1] > JOY_TRIG)
+        switches |= SLOW;
+    if (joy_buttons[BUT0])
+        switches |= OFIRE;
+    if (joy_buttons[BUT0+1])
+        switches |= OHYPER;
+    if (joy_buttons[BUT0+2])
+        switches |= BEACON;
 
-  if (joy_axes[JOY1] > JOY_TRIG)
-    switches |= OCCW << 18;
-  else if (joy_axes[JOY1] < -JOY_TRIG)
-    switches |= OCW << 18;
-  if (joy_axes[JOY1+1] < -JOY_TRIG)
-    switches |= FAST << 18;
-  if (joy_axes[JOY1+1] > JOY_TRIG)
-    switches |= SLOW << 18;
-  if (joy_buttons[BUT1])
-    switches |= OFIRE << 18;
-  if (joy_buttons[BUT1+1])
-    switches |= OHYPER << 18;
-  if (joy_buttons[BUT1+2])
-    switches |= BEACON << 18;
+    if (joy_axes[JOY1] > JOY_TRIG)
+        switches |= OCCW << 18;
+    else if (joy_axes[JOY1] < -JOY_TRIG)
+        switches |= OCW << 18;
+    if (joy_axes[JOY1+1] < -JOY_TRIG)
+        switches |= FAST << 18;
+    if (joy_axes[JOY1+1] > JOY_TRIG)
+        switches |= SLOW << 18;
+    if (joy_buttons[BUT1])
+        switches |= OFIRE << 18;
+    if (joy_buttons[BUT1+1])
+        switches |= OHYPER << 18;
+    if (joy_buttons[BUT1+2])
+        switches |= BEACON << 18;
 
-  return switches;
+    return switches;
 }
 
 t_stat ocnsls_devio(uint32 dev, uint64 *data) {