diff --git a/rootfs.manifest b/rootfs.manifest
index 54085cc..36f8a8f 100644
--- a/rootfs.manifest
+++ b/rootfs.manifest
@@ -745,6 +745,7 @@ file /share/examples/c/stdarg.c
 file /share/examples/c/test1.c
 file /share/examples/c/test2.c
 file /share/examples/c/test3.c
+file /share/examples/c/tetris.c
 
 #
 # Files: /share/examples/smallc
@@ -772,6 +773,7 @@ file /share/examples/sensors/README.txt
 file /share/examples/sensors/buzzer.c
 file /share/examples/sensors/buzzer.sh
 file /share/examples/sensors/irled.c
+file /share/examples/sensors/joystick.c
 file /share/examples/sensors/laser.c
 file /share/examples/sensors/laser.sh
 file /share/examples/sensors/led2.c
diff --git a/share/examples/c/Makefile b/share/examples/c/Makefile
index ada7a70..e01a444 100644
--- a/share/examples/c/Makefile
+++ b/share/examples/c/Makefile
@@ -1,6 +1,6 @@
 CC      = cc
 PROG    = hello stdarg skeleton primelist primesum test1 test2 test3 \
-          gpio adc rain q8
+          gpio adc rain q8 tetris
 
 all:    $(PROG)
 
@@ -31,6 +31,9 @@ rain:   rain.c
 q8:     q8.c
 	$(CC) $(CFLAGS) -o $@ $(LDFLAGS) $?
 
+tetris: tetris.c
+	$(CC) $(CFLAGS) -o $@ $(LDFLAGS) $?
+
 test1:	test1.c
 	$(CC) $(CFLAGS) -o $@ $(LDFLAGS) $?
 
diff --git a/share/examples/c/Makefile-host b/share/examples/c/Makefile-host
index f828620..1430853 100644
--- a/share/examples/c/Makefile-host
+++ b/share/examples/c/Makefile-host
@@ -11,5 +11,11 @@ chello:         chello.o
 		${SIZE} chello.elf
 		${ELF2AOUT} chello.elf $@
 
+tetris:         tetris.o
+		${CC} ${LDFLAGS} -o tetris.elf tetris.o ${LIBS}
+		${OBJDUMP} -S tetris.elf > tetris.dis
+		${SIZE} tetris.elf
+		${ELF2AOUT} tetris.elf $@
+
 clean:
 		rm -f *.o *.elf ${MAN} chello stdarg *.elf *.dis tags *~
diff --git a/share/examples/c/tetris.c b/share/examples/c/tetris.c
new file mode 100644
index 0000000..714ae98
--- /dev/null
+++ b/share/examples/c/tetris.c
@@ -0,0 +1,656 @@
+/*
+ * Tetris (C) Copyright 1995, Vadim Antonov
+ * Port to RetroBSD (C) 2015, Serge Vakulenko
+ *
+ * This program is designed to run on Olimex Duinomite board
+ * with SainSmart Graphic LCD4884 shield, modified for 3.3V.
+ *
+ * Permission to use, copy, modify, and distribute this software
+ * and its documentation for any purpose and without fee is hereby
+ * granted, provided that the above copyright notice appear in all
+ * copies and that both that the copyright notice and this
+ * permission notice and warranty disclaimer appear in supporting
+ * documentation, and that the name of the author not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ *
+ * The author disclaim all warranties with regard to this
+ * software, including all implied warranties of merchantability
+ * and fitness.  In no event shall the author be liable for any
+ * special, indirect or consequential damages or any damages
+ * whatsoever resulting from loss of use, data or profits, whether
+ * in an action of contract, negligence or other tortious action,
+ * arising out of or in connection with the use or performance of
+ * this software.
+ */
+#include <stdlib.h>
+#include <string.h>
+#include <sys/gpio.h>
+
+#define PITWIDTH    12
+#define PITDEPTH    21
+
+#define NSHAPES     7
+#define NBLOCKS     5
+
+#define FIN         999
+
+typedef struct {
+    int x, y;
+} coord_t;
+
+typedef struct {
+    int dx, dy;
+    coord_t p[NBLOCKS];
+} shape_t;
+
+const shape_t shape [NSHAPES] = {
+/* OOOO */  { 0, 3, { {0,0}, {0,1}, {0,2}, {0,3}, {FIN,FIN} } },
+
+/* O   */   { 1, 2, { {0,0}, {1,0}, {1,1}, {1,2}, {FIN,FIN} } },
+/* OOO */
+
+/*  O  */   { 1, 2, { {0,1}, {1,0}, {1,1}, {1,2}, {FIN,FIN} } },
+/* OOO */
+
+/*   O */   { 1, 2, { {0,2}, {1,0}, {1,1}, {1,2}, {FIN,FIN} } },
+/* OOO */
+
+/*  OO */   { 1, 2, { {0,0}, {0,1}, {1,1}, {1,2}, {FIN,FIN} } },
+/* OO  */
+
+/* OO  */   { 1, 2, { {0,1}, {0,2}, {1,0}, {1,1}, {FIN,FIN} } },
+/*  OO */
+
+/* OO */    { 1, 1, { {0,0}, {0,1}, {1,0}, {1,1}, {FIN,FIN} } },
+/* OO */
+};
+
+int pit [PITDEPTH+1] [PITWIDTH];
+int pitcnt [PITDEPTH];
+coord_t old [NBLOCKS], new [NBLOCKS], chk [NBLOCKS];
+int gpio;                               /* File descriptor of GPIO driver. */
+int adc3;                               /* File descriptor of ADC3 driver. */
+
+/*-------------------------------------------------------------
+ * Definitions for a "digital" joystick at A0 analog input.
+ * Button values are determined by resistors on a board.
+ */
+enum {
+    JOYSTICK_LEFT,
+    JOYSTICK_SELECT,
+    JOYSTICK_DOWN,
+    JOYSTICK_RIGHT,
+    JOYSTICK_UP,
+    JOYSTICK_IDLE = -1,
+};
+
+/*
+ * Initialize ADC for a joystick.
+ */
+void joystick_init()
+{
+    /* Open ADC driver. */
+    adc3 = open("/dev/adc3", 0);
+    if (adc3 < 0) {
+        perror("/dev/adc3");
+        exit(-1);
+    }
+}
+
+/*
+ * Get a state of joystick.
+ * Convert ADC value to key number.
+ * Input buttons are connected to a series network of resistors:
+ * GND - 3.3k - 1k - 620 - 330 - 2k - +3.3V
+ * Expected values are:
+ * 0 - 144 - 329 - 506 - 741 - 1023
+ */
+int joystick_get()
+{
+    static const unsigned level[5] = { 72, 236, 417, 623, 882 };
+    unsigned input, k;
+    char buf[16];
+
+    if (read(adc3, buf, sizeof(buf)) <= 0) {
+        perror("adc");
+        exit(-1);
+    }
+    input = strtol(buf, 0, 10);
+    for (k=0; k<5; k++) {
+        if (input < level[k]) {
+            return k;
+        }
+    }
+    return JOYSTICK_IDLE;
+}
+
+/*-------------------------------------------------------------
+ * Routines for Nokia 5110 display.
+ * See Philips PCD8544 datasheet.
+ */
+#define NROW 48
+#define NCOL 84
+
+/*
+ * Pinout for SainSmart Graphic LCD4884 Shield.
+ */
+#define MASKE_LCD_SCK   (1 << 2)    /* signal D2, pin RE2 */
+#define MASKE_LCD_MOSI  (1 << 3)    /* signal D3, pin RE3 */
+#define MASKE_LCD_DC    (1 << 4)    /* signal D4, pin RE4 */
+#define MASKE_LCD_CS    (1 << 5)    /* signal D5, pin RE5 */
+#define MASKE_LCD_RST   (1 << 6)    /* signal D6, pin RE6 */
+#define MASKE_LCD_BL    (1 << 7)    /* signal D7, pin RE7 */
+
+static unsigned char gpanel_screen [NROW*NCOL/8];
+int gpanel_row, gpanel_col;
+
+static inline void lcd_cs(unsigned on)
+{
+    if (on) {
+        ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_CS);
+    } else {
+        ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_CS);
+    }
+}
+
+static inline void lcd_rst(unsigned on)
+{
+    if (on) {
+        ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_RST);
+    } else {
+        ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_RST);
+    }
+}
+
+static inline void lcd_dc(unsigned on)
+{
+    if (on) {
+        ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_DC);
+    } else {
+        ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_DC);
+    }
+}
+
+static inline void lcd_bl(unsigned on)
+{
+    if (on) {
+        ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_BL);
+    } else {
+        ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_BL);
+    }
+}
+
+static inline void lcd_mosi(unsigned on)
+{
+    if (on) {
+        ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_MOSI);
+    } else {
+        ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_MOSI);
+    }
+}
+
+static inline void lcd_sck(unsigned on)
+{
+    if (on) {
+        ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_SCK);
+    } else {
+        ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_SCK);
+    }
+}
+
+static void lcd_write(unsigned byte, unsigned data_flag)
+{
+    unsigned i;
+
+    lcd_cs(0);
+    lcd_dc(data_flag);
+    for (i=0; i<8; i++, byte<<=1) {
+        lcd_mosi(byte & 0x80);          /* SDIN = bit[i] */
+        lcd_sck(0);                     /* SCLK = 0 */
+        lcd_sck(1);                     /* SCLK = 1 */
+    }
+    lcd_cs(1);
+}
+
+/*
+ * Set up hardware for communication to Nokia 5110 LCD Display.
+ * Do not clear the display.
+ * Leave backlight turned off.
+ */
+void gpanel_init()
+{
+    gpanel_row = 0;
+    gpanel_col = 0;
+
+    /*
+     * Set pins as outputs.
+     */
+    ioctl(gpio, GPIO_PORTE | GPIO_CONFOUT, MASKE_LCD_SCK |
+        MASKE_LCD_MOSI | MASKE_LCD_DC | MASKE_LCD_CS |
+        MASKE_LCD_RST | MASKE_LCD_BL);
+    ioctl(gpio, GPIO_PORTE | GPIO_SET, MASKE_LCD_RST | MASKE_LCD_CS);
+    ioctl(gpio, GPIO_PORTE | GPIO_CLEAR, MASKE_LCD_SCK |
+        MASKE_LCD_MOSI | MASKE_LCD_DC | MASKE_LCD_BL);
+
+    /* Turn off backlight. */
+    lcd_bl(0);
+
+    /* Reset the display. */
+    lcd_rst(0);
+    usleep(10000);          // need 1 usec
+    lcd_rst(1);
+    usleep(10000);          // need 1 usec
+
+    lcd_write(0x21, 0);     // Enable extended instruction set
+    lcd_write(0xbf, 0);     // Set Vop - contrast level
+    lcd_write(0x04, 0);     // Set temperature coefficient to 0
+    lcd_write(0x14, 0);     // Set bias to 4
+    lcd_write(0x20, 0);     // Back to normal instruction set
+    lcd_write(0x0c, 0);     // Set normal mode
+
+    /* Enable backlight. */
+    lcd_bl(1);
+}
+
+/*
+ * Clear the the LCD screen.
+ */
+void gpanel_clear()
+{
+    unsigned i;
+
+    /* Clear data */
+    lcd_write(0x40, 0);
+    lcd_write(0x80, 0);
+    for (i=0; i<NROW*NCOL/8; i++) {
+        gpanel_screen[i] = 0;
+        lcd_write(0, 1);
+    }
+    gpanel_row = 0;
+    gpanel_col = 0;
+}
+
+/*
+ * Lights a single pixel in the specified color
+ * at the specified x and y addresses
+ */
+void gpanel_pixel(int x, int y, int color)
+{
+    unsigned char *data;
+
+    if (x >= NCOL || y >= NROW)
+        return;
+    data = &gpanel_screen [(y >> 3) * NCOL + x];
+
+    if (color)
+        *data |= 1 << (y & 7);
+    else
+        *data &= ~(1 << (y & 7));
+
+    lcd_write(0x40 | (y >> 3), 0);
+    lcd_write(0x80 | x, 0);
+    lcd_write(*data, 1);
+}
+
+/*
+ * Draw a filled rectangle in the specified color from (x1,y1) to (x2,y2).
+ *
+ * The best way to fill a rectangle is to take advantage of the "wrap-around" featute
+ * built into the Philips PCF8833 controller. By defining a drawing box, the memory can
+ * be simply filled by successive memory writes until all pixels have been illuminated.
+ */
+void gpanel_rect_filled(int x0, int y0, int x1, int y1, int color)
+{
+    /* Temporary solution */
+    int xmin, xmax, ymin, ymax, x, y;
+
+    /* calculate the min and max for x and y directions */
+    if (x0 <= x1) {
+        xmin = x0;
+        xmax = x1;
+    } else {
+        xmin = x1;
+        xmax = x0;
+    }
+    if (y0 <= y1) {
+        ymin = y0;
+        ymax = y1;
+    } else {
+        ymin = y1;
+        ymax = y0;
+    }
+    for (y=ymin; y<=ymax; y++)
+        for (x=xmin; x<=xmax; x++)
+            gpanel_pixel(x, y, color);
+}
+
+/*-------------------------------------------------------------
+ * Output piece coordinates given its center and angle
+ */
+void translate(const shape_t *t, coord_t c, int a, coord_t *res)
+{
+    coord_t org, tmp;
+    int yw, xw, i;
+
+    if (a & 1) {            /* 90 deg */
+        xw = t->dy;
+        yw = t->dx;
+    } else {
+        xw = t->dx;
+        yw = t->dy;
+    }
+    org = c;
+    org.x -= (xw + 1) / 2;
+    org.y -= yw / 2;
+    if (org.y < 0)
+        org.y = 0;
+    if (org.y + yw >= PITWIDTH && c.y <= PITWIDTH)
+        org.y = PITWIDTH-1 - yw;
+    for (i=0; t->p[i].x!=FIN; i++) {
+        switch (a) {
+        case 0:
+            res[i].x = t->p[i].x;
+            res[i].y = t->p[i].y;
+            break;
+        case 3:
+            res[i].x = xw - t->p[i].y;
+            res[i].y = t->p[i].x;
+            break;
+        case 2:
+            res[i].x = xw - t->p[i].x;
+            res[i].y = yw - t->p[i].y;
+            break;
+        case 1:
+            res[i].x = t->p[i].y;
+            res[i].y = yw - t->p[i].x;
+        }
+        res[i].x += org.x;
+        res[i].y += org.y;
+    }
+    res[i].x = res[i].y = FIN;
+
+    do {
+        xw = 0;
+        for (i=0; res[i+1].x!=FIN; i++) {
+            if (res[i].x < res[i+1].x)
+                continue;
+            if (res[i].x == res[i+1].x && res[i].y <= res[i+1].y)
+                continue;
+            xw++;
+            tmp = res[i];
+            res[i] = res[i+1];
+            res[i+1] = tmp;
+        }
+    } while (xw);
+}
+
+/*
+ * Draw the block
+ */
+void draw_block(int h, int w, int visible)
+{
+    h *= 4;
+    w *= 4;
+    if (visible) {
+        gpanel_rect_filled(NCOL-1 - h, w, NCOL-1 - (h + 3), w + 3, 1);
+    } else {
+        gpanel_rect_filled(NCOL-1 - h, w, NCOL-1 - (h + 3), w + 3, 0);
+
+        if (h == (PITDEPTH-1)*5)
+            gpanel_pixel(NCOL-1 - (h + 3), w + 2, 1);
+
+        if (w == 0)
+            gpanel_pixel(NCOL-1 - (h + 2), w, 1);
+        else if (w % 16 == 12)
+            gpanel_pixel(NCOL-1 - (h + 2), w + 3, 1);
+    }
+}
+
+/*
+ * Move the piece
+ */
+void move(coord_t *old, coord_t *new)
+{
+    for (;;) {
+        if (old->x == FIN) {
+draw:       if (new->x == FIN)
+                break;
+            if (new->x >= 0)
+                draw_block(new->x, new->y, 1);
+            new++;
+            continue;
+        }
+        if (new->x == FIN) {
+clear:      if (old->x >= 0)
+                draw_block(old->x, old->y, 0);
+            old++;
+            continue;
+        }
+        if (old->x > new->x)
+            goto draw;
+        if (old->x < new->x)
+            goto clear;
+        if (old->y > new->y)
+            goto draw;
+        if (old->y != new->y)
+            goto clear;
+        /* old & new at the same place */
+        old++;
+        new++;
+    }
+}
+
+/*
+ * Draw the pit
+ */
+void clear()
+{
+    int h, w;
+
+    for (h=0; h<PITDEPTH; h++) {
+        for (w=0; w<PITWIDTH; w++) {
+            draw_block(h, w, 0);
+            pit[h][w] = 0;
+        }
+        pitcnt[h] = 0;
+    }
+    for (w=0; w<PITWIDTH; w++)
+        pit[PITDEPTH][w] = 1;
+}
+
+/*
+ * The piece reached the bottom
+ */
+void stopped(coord_t *c)
+{
+    int h, nfull, w, k;
+
+    /* Count the full lines */
+    nfull = 0;
+    for (; c->x!=FIN; c++) {
+        if (c->x <= 0) {
+            /* Game over. */
+            clear();
+            return;
+        }
+        pit[c->x][c->y] = 1;
+        ++pitcnt[c->x];
+        if (pitcnt[c->x] == PITWIDTH)
+            nfull++;
+    }
+    if (! nfull)
+        return;
+
+    /* Clear upper nfull lines */
+    for (h=0; h<nfull; h++) {
+        for (w=0; w<PITWIDTH; w++) {
+            if (pit[h][w]) {
+                draw_block(h, w, 0);
+            }
+        }
+    }
+
+    /* Move lines down */
+    k = nfull;
+    for (h=nfull; h<PITDEPTH && k>0; h++) {
+        if (pitcnt[h-k] == PITWIDTH) {
+            k--;
+            h--;
+            continue;
+        }
+        for (w=0; w<PITWIDTH; w++) {
+            if (pit[h][w] != pit[h-k][w]) {
+                draw_block(h, w, pit[h-k][w]);
+            }
+        }
+    }
+
+    /* Now fix the pit contents */
+    for (h=PITDEPTH-1; h>0; h--) {
+        if (pitcnt[h] != PITWIDTH)
+            continue;
+        memmove(pit[0]+PITWIDTH, pit[0], h * sizeof(pit[0]));
+        memset(pit[0], 0, sizeof(pit[0]));
+        memmove(pitcnt+1, pitcnt, h * sizeof(pitcnt[0]));
+        pitcnt[0] = 0;
+        h++;
+    }
+}
+
+int main()
+{
+    int ptype;              /* Piece type */
+    int angle, anew;        /* Angle */
+    int msec;               /* Timeout */
+    coord_t c, cnew, *cp;
+    unsigned up_pressed = 0, left_pressed = 0;
+    unsigned right_pressed = 0, down_pressed = 0;
+
+    joystick_init();
+    gpanel_init();
+    gpanel_clear();
+
+    /* Draw the pit */
+    clear();
+
+newpiece:
+    ptype = rand() % NSHAPES;
+    angle = rand() % 3;
+
+    c.y = PITWIDTH/2 - 1;
+    for (c.x= -2; ; c.x++) {
+        translate(&shape[ptype], c, angle, new);
+        for (cp=new; cp->x!=FIN; cp++) {
+            if (cp->x >= 0)
+                goto ok;
+        }
+    }
+ok:
+    /* Draw new piece */
+    for (cp=new; cp->x!=FIN; cp++) {
+        if (cp->x >= 0) {
+            draw_block(cp->x, cp->y, 1);
+        }
+    }
+    memcpy(old, new, sizeof old);
+
+    msec = 500;
+    for (;;) {
+        cnew = c;
+        anew = angle;
+
+        if (msec <= 0) {
+            /* Timeout: move down */
+            msec = 500;
+            cnew.x++;
+            translate(&shape[ptype], cnew, anew, chk);
+            for (cp=chk; cp->x!=FIN; cp++) {
+                if (cp->x >= 0 && pit[cp->x][cp->y]) {
+                    stopped(new);
+                    goto newpiece;
+                }
+            }
+            goto check;
+        }
+
+        int key = joystick_get();
+        if (key != JOYSTICK_RIGHT)
+            right_pressed = 0;
+        else if (! right_pressed) {
+            right_pressed = 1;
+
+            /* Right: rotate */
+            if (--anew < 0)
+                anew = 3;
+            translate(&shape[ptype], cnew, anew, chk);
+            goto check;
+        }
+
+        if (key != JOYSTICK_UP)
+            up_pressed = 0;
+        else if (! up_pressed) {
+            up_pressed = 1;
+
+            /* Up: move left. */
+            if (cnew.y <= 0)
+                continue;
+            cnew.y--;
+            translate(&shape[ptype], cnew, anew, chk);
+            goto check;
+        }
+
+        if (key != JOYSTICK_DOWN)
+            down_pressed = 0;
+        else if (! down_pressed) {
+            down_pressed = 1;
+
+            /* Down: move right */
+            if (cnew.y >= PITWIDTH-1)
+                continue;
+            cnew.y++;
+            translate(&shape[ptype], cnew, anew, chk);
+            goto check;
+        }
+
+        if (key != JOYSTICK_LEFT)
+            left_pressed = 0;
+        else if (! left_pressed) {
+            left_pressed = 1;
+
+            /* Right: drop */
+            for (;;) {
+                cnew.x++;
+                translate(&shape[ptype], cnew, anew, chk);
+                for (cp=chk; cp->x!=FIN; cp++) {
+                    if (cp->x >= 0 && pit[cp->x][cp->y]) {
+                        cnew.x--;
+                        translate(&shape[ptype], cnew, anew, chk);
+                        move(new, chk);
+                        stopped(chk);
+                        goto newpiece;
+                    }
+                }
+            }
+        }
+
+        usleep(10000);
+        msec -= 10;
+        continue;
+check:
+        for (cp=chk; cp->x!=FIN; cp++) {
+            if (cp->y < 0 || cp->y >= PITWIDTH)
+                goto done;
+        }
+        for (cp=chk; cp->x!=FIN; cp++) {
+            if (cp->x >= 0 && pit[cp->x][cp->y])
+                goto done;
+        }
+        c = cnew;
+        angle = anew;
+        memcpy(old, new, sizeof old);
+        memcpy(new, chk, sizeof new);
+        move(old, new);
+done:   ;
+    }
+}
diff --git a/share/examples/sensors/Makefile b/share/examples/sensors/Makefile
index 5e6eb74..0f3e15e 100644
--- a/share/examples/sensors/Makefile
+++ b/share/examples/sensors/Makefile
@@ -1,4 +1,4 @@
-PROG    = led2 led3 relay buzzer laser pbuzz irled
+PROG    = led2 led3 relay buzzer laser pbuzz irled joystick
 
 all:    $(PROG)
 
@@ -23,5 +23,8 @@ led3:   led3.c
 irled:  irled.c
 	cc $? -o $@
 
+joystick: joystick.c
+	cc $? -o $@
+
 clean:
 	rm -f *.o *~ $(PROG)
diff --git a/share/examples/sensors/joystick.c b/share/examples/sensors/joystick.c
new file mode 100644
index 0000000..91af108
--- /dev/null
+++ b/share/examples/sensors/joystick.c
@@ -0,0 +1,76 @@
+/*
+ * Example for RetroBSD on Olimex Duinomite board.
+ * Joystick is connected to A0, A1 and D7 pin of Duinomite board.
+ */
+#include <stdio.h>
+#include <sys/ioctl.h>
+#include <sys/gpio.h>
+
+/*
+ * Pin D7 is connected to signal RE7 on pic32 chip.
+ */
+#define MASK_BUTTON     (1 << 7)    /* signal RE7 */
+
+/*
+ * Read value from analog-to-digital converter.
+ * Scale to given max value.
+ */
+int readadc(int fd, int max)
+{
+    char buf[16];
+    int val;
+
+    if (read(fd, buf, sizeof(buf)) <= 0) {
+        perror("adc");
+        exit(-1);
+    }
+    val = strtol(buf, 0, 10);
+    return val * max / 1024;
+}
+
+int main()
+{
+    int gpio, adc3, adc4, porte, x, y;
+
+    /* Open GPIO driver. */
+    gpio = open("/dev/porta", 1);
+    if (gpio < 0) {
+        perror("/dev/porta");
+        return -1;
+    }
+
+    /* Open ADC driver. */
+    adc3 = open("/dev/adc3", 0);
+    if (adc3 < 0) {
+        perror("/dev/adc3");
+        return -1;
+    }
+    adc4 = open("/dev/adc4", 0);
+    if (adc4 < 0) {
+        perror("/dev/adc4");
+        return -1;
+    }
+
+    /* Configure D7 pin is input, active low. */
+    ioctl(gpio, GPIO_PORTE | GPIO_CONFIN, MASK_BUTTON);
+
+    /* Clear screen. */
+    printf("\33[2J");
+
+    for (;;) {
+        /* Poll joystick every 20 msec. */
+        usleep(20000);
+        porte = ioctl(gpio, GPIO_PORTE | GPIO_POLL, 0);
+        x = readadc(adc3, 50);
+        y = readadc(adc4, 25);
+
+        if (~porte & MASK_BUTTON) {
+            /* When button pressed - clear screen. */
+            printf("\33[2J");
+        }
+        printf("\33[H%u, %u  ", x, y);
+        printf("\33[%u;%uHX", y, 78 - x);
+        fflush(stdout);
+    }
+    return 0;
+}