diff --git a/gr-sim/tunnel/Makefile b/gr-sim/tunnel/Makefile
new file mode 100644
index 00000000..6ef11233
--- /dev/null
+++ b/gr-sim/tunnel/Makefile
@@ -0,0 +1,31 @@
+CC = gcc
+CFLAGS = -Wall -O2 -I.. -g
+LFLAGS = -lm
+
+SDL_LIBS= `sdl-config --libs`
+SDL_INCLUDE= `sdl-config --cflags`
+GR_SIM = ../gr-sim.a
+
+all:	tunnel tunnel2
+
+####
+
+tunnel:	tunnel.o $(GR_SIM)
+	$(CC) $(LFLAGS) $(SDL_LIBS) -o tunnel tunnel.o $(GR_SIM)
+
+tunnel.o:	tunnel.c
+	$(CC) $(CFLAGS) -c tunnel.c
+
+####
+
+tunnel2:	tunnel2.o $(GR_SIM)
+	$(CC) $(LFLAGS) $(SDL_LIBS) -o tunnel2 tunnel2.o $(GR_SIM)
+
+tunnel2.o:	tunnel2.c
+	$(CC) $(CFLAGS) -c tunnel2.c
+
+
+####
+
+clean:	
+	rm -f *~ *.o tunnel tunnel2
diff --git a/gr-sim/tunnel/tunnel.c b/gr-sim/tunnel/tunnel.c
new file mode 100644
index 00000000..bf49fb77
--- /dev/null
+++ b/gr-sim/tunnel/tunnel.c
@@ -0,0 +1,123 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <math.h>
+
+#include "gr-sim.h"
+#include "tfv_utils.h"
+#include "tfv_zp.h"
+
+
+#define SCALE	12.0
+#define STEP	22.5
+#define DELTA	(STEP/16.0)
+
+//#define SCALE	4.0
+//#define STEP	45.0
+//#define DELTA	(STEP/3.0)
+
+//#define SCALE	8.0
+//#define STEP	22.5
+//#define DELTA	(STEP/3.0)
+
+
+static double d2r(double xx) {
+	return (xx/180.0)*3.1415926535897932384;
+}
+
+int main(int argc, char **argv) {
+
+	int xx,yy,ch,i;
+	double theta,delta=0.0;
+
+
+	grsim_init();
+	gr();
+
+//	clear_screens();
+
+	ram[DRAW_PAGE]=PAGE0;
+	clear_bottom();
+	ram[DRAW_PAGE]=PAGE1;
+	clear_bottom();
+	ram[DRAW_PAGE]=PAGE2;
+	clear_bottom();
+
+
+//	clear_bottom(PAGE0);
+//	clear_bottom(PAGE1);
+//	clear_bottom(PAGE2);
+
+//	grsim_unrle(demo_rle,0x400);
+//	grsim_unrle(demo_rle,0xc00);
+
+//	gr_copy_to_current(0xc00);
+//	page_flip();
+//	gr_copy_to_current(0xc00);
+//	page_flip();
+
+	ram[DRAW_PAGE]=PAGE0;
+
+	while(1) {
+
+		ch=repeat_until_keypressed();
+		if (ch=='q') break;
+
+		clear_top();
+
+		for(theta=0;theta<360.0;theta+=STEP) {
+			xx=cos(d2r(theta+delta))*SCALE+20;
+			yy=sin(d2r(theta+delta))*SCALE*1.33+24;
+
+#if 1
+			color_equals(15);
+			plot(xx,yy);
+
+			if (xx<20) {
+				color_equals(1);
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+			else {
+				color_equals(2);
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+
+#endif
+
+#if 0
+			color_equals(4);
+			plot(xx,yy);
+			if (xx>20) {
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+#endif
+#if 0
+
+			color_equals(4);
+//			plot(xx,yy);
+			if (xx<20) {
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+#endif
+
+		}
+		delta+=DELTA;
+
+		grsim_update();
+
+	}
+
+
+	return 0;
+}
+
diff --git a/gr-sim/tunnel/tunnel2.c b/gr-sim/tunnel/tunnel2.c
new file mode 100644
index 00000000..c3b4bc4d
--- /dev/null
+++ b/gr-sim/tunnel/tunnel2.c
@@ -0,0 +1,123 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <math.h>
+
+#include "gr-sim.h"
+#include "tfv_utils.h"
+#include "tfv_zp.h"
+
+
+#define SCALE	8.0
+#define STEP	30
+#define DELTA	(STEP/10.0)
+
+//#define SCALE	4.0
+//#define STEP	45.0
+//#define DELTA	(STEP/3.0)
+
+//#define SCALE	8.0
+//#define STEP	22.5
+//#define DELTA	(STEP/3.0)
+
+
+static double d2r(double xx) {
+	return (xx/180.0)*3.1415926535897932384;
+}
+
+int main(int argc, char **argv) {
+
+	int xx,yy,ch,i;
+	double theta,delta=0.0;
+
+
+	grsim_init();
+	gr();
+
+//	clear_screens();
+
+	ram[DRAW_PAGE]=PAGE0;
+	clear_bottom();
+	ram[DRAW_PAGE]=PAGE1;
+	clear_bottom();
+	ram[DRAW_PAGE]=PAGE2;
+	clear_bottom();
+
+
+//	clear_bottom(PAGE0);
+//	clear_bottom(PAGE1);
+//	clear_bottom(PAGE2);
+
+//	grsim_unrle(demo_rle,0x400);
+//	grsim_unrle(demo_rle,0xc00);
+
+//	gr_copy_to_current(0xc00);
+//	page_flip();
+//	gr_copy_to_current(0xc00);
+//	page_flip();
+
+	ram[DRAW_PAGE]=PAGE0;
+
+	while(1) {
+
+		ch=repeat_until_keypressed();
+		if (ch=='q') break;
+
+		clear_top();
+
+		for(theta=0;theta<360.0;theta+=STEP) {
+			xx=cos(d2r(theta+delta))*SCALE+20;
+			yy=sin(d2r(theta+delta))*SCALE*1.33+24;
+
+#if 1
+			color_equals(15);
+			plot(xx,yy);
+
+			if (xx<20) {
+				color_equals(1);
+				for(i=xx;i<(20-xx)+20;i++) {
+					plot(i,yy);
+				}
+			}
+			else {
+				color_equals(2);
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+
+#endif
+
+#if 0
+			color_equals(4);
+			plot(xx,yy);
+			if (xx>20) {
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+#endif
+#if 0
+
+			color_equals(4);
+//			plot(xx,yy);
+			if (xx<20) {
+				for(i=xx;i<40;i++) {
+					plot(i,yy);
+				}
+			}
+#endif
+
+		}
+		delta+=DELTA;
+
+		grsim_update();
+
+	}
+
+
+	return 0;
+}
+