diff --git a/fer.sav b/fer.sav
new file mode 100644
index 0000000..8e62f56
Binary files /dev/null and b/fer.sav differ
diff --git a/main.cpp b/main.cpp
index c3b7413..9871456 100644
--- a/main.cpp
+++ b/main.cpp
@@ -10,6 +10,7 @@
 #include <string.h>
 #include "ui.h"
 #include "ui_menu.h"
+#include "z80analyze.h"
 
 uint8_t memory[65536];
 uint32_t time = 0;
@@ -24,10 +25,16 @@ namespace actions
         zxscreen::refresh(dt);
     }
 
-    int berserk(int value)
+    int fastload(int value)
     {
-        zx_tape::setberserk(!zx_tape::getberserk());
-        return zx_tape::getberserk();
+        zx_tape::toggleOption(ZXTAPE_OPTION_FAST_LOAD);
+        return zx_tape::getOption(ZXTAPE_OPTION_FAST_LOAD);
+    }
+
+    int stopatend(int value)
+    {
+        zx_tape::toggleOption(ZXTAPE_OPTION_STOP_AT_END);
+        return zx_tape::getOption(ZXTAPE_OPTION_STOP_AT_END);
     }
 
     int decZoom(int value)
@@ -47,6 +54,12 @@ namespace actions
         zxscreen::toggleFullscreen();
         return zxscreen::getFullscreen();
     }
+
+    int showAnalyzer(int value)
+    {
+        z80analyze::show();
+        return 0;
+    }
 }
 
 int main(int argc, char *argv[])
@@ -73,13 +86,18 @@ int main(int argc, char *argv[])
     ui::menu::addoption(menu, "SAVE STATE", nullptr);
 
     menu = ui::menu::addsubmenu("TAPE");
-    ui::menu::addbooloption(menu, "BERSERK MODE", zx_tape::getberserk(), actions::berserk);
+    ui::menu::addbooloption(menu, "BERSERK MODE", zx_tape::getOption(ZXTAPE_OPTION_FAST_LOAD), actions::fastload);
+    ui::menu::addbooloption(menu, "STOP AT END", zx_tape::getOption(ZXTAPE_OPTION_STOP_AT_END), actions::stopatend);
 
     menu = ui::menu::addsubmenu("SCREEN");
     ui::menu::addoption(menu, "DEC ZOOM", actions::decZoom);
     ui::menu::addoption(menu, "INC ZOOM", actions::incZoom);
     ui::menu::addbooloption(menu, "FULLSCREEN", zxscreen::getFullscreen(), actions::fullscreen);
 
+    menu = ui::menu::addsubmenu("EMULATION");
+    ui::menu::addbooloption(menu, "STOP ON INVALID OP", z80::getOption(Z80_OPTION_STOP_ON_INVALID), actions::decZoom);
+    ui::menu::addoption(menu, "SHOW ANALYZER", actions::showAnalyzer);
+
     zx_ula::sound_init();
 
     zx_tape::load("fernandomartin.tap");
@@ -206,9 +224,9 @@ int main(int argc, char *argv[])
                 zxscreen::redraw();
             } else {
                 //if (z80::getPC()==0x05C8) zx_tape::go_berserk();
-                bool berserk=false;
-                if (zx_tape::getplaying() && zx_tape::getberserk()) { berserk=true; time = SDL_GetTicks(); }
-                while (zx_tape::getplaying() && zx_tape::getberserk())
+                bool fastload=false;
+                if (zx_tape::getplaying() && zx_tape::getOption(ZXTAPE_OPTION_FAST_LOAD)) { fastload=true; time = SDL_GetTicks(); }
+                while (zx_tape::getplaying() && zx_tape::getOption(ZXTAPE_OPTION_FAST_LOAD))
                 {
 //                    zx_tape::update(z80::step());
                     uint8_t dt = z80::step();
@@ -221,7 +239,7 @@ int main(int argc, char *argv[])
                     //zx_ula::sound_update(dt);
                     //zxscreen::refresh(dt);
                 }
-                if (berserk) { printf("%i\n", SDL_GetTicks()-time); t_states=0; }
+                if (fastload) { printf("%i\n", SDL_GetTicks()-time); t_states=0; }
                 // En cada bucle fem 10 pasos de la CPU, sino s'ofega
                 for (int i=0;i<5;++i) {
                     uint8_t dt = z80::step();
diff --git a/z80.cpp b/z80.cpp
index 34bb329..e286f1a 100644
--- a/z80.cpp
+++ b/z80.cpp
@@ -9,6 +9,7 @@ namespace z80
     static uint8_t memtag[65536];
     static uint32_t t = 0;
     static uint16_t current_opcode_address = 0;
+    bool options[Z80_NUM_OPTIONS] = { true };
 
     int (*in_ports[256])(int);
     void (*out_ports[256])(int, int);
@@ -1032,9 +1033,8 @@ namespace z80
 
     void INVALID(uint8_t opcode)
     {
-        // [TODO]
         printf("INVALID OPCODE AT: %04x\n", current_opcode_address);
-        z80debug::stop();
+        if (options[Z80_OPTION_STOP_ON_INVALID]) z80debug::stop();
     }
 
     void reset(uint8_t* mem)
@@ -2738,4 +2738,19 @@ namespace z80
 
     uint8_t getMemTag(const uint16_t addr) { return memtag[addr]; };
 
+    const bool getOption(const int option)
+    {
+        return options[option];
+    }
+
+    void setOption(const int option, const bool value)
+    {
+        options[option] = value;
+    }
+
+    void toggleOption(const int option)
+    {
+        options[option] = !options[option];
+    }
+
 }
\ No newline at end of file
diff --git a/z80.h b/z80.h
index 957efa4..7920c39 100644
--- a/z80.h
+++ b/z80.h
@@ -9,6 +9,9 @@ namespace z80
     #define MEMTAG_CODE     2
     #define MEMTAG_DATA     3
 
+    #define Z80_OPTION_STOP_ON_INVALID  0
+    #define Z80_NUM_OPTIONS 1
+    
     void reset(uint8_t* mem);
     void connect_port(int num, int (*in_ptr)(int), void (*out_ptr)(int,int));
     void interrupt();
@@ -34,4 +37,8 @@ namespace z80
 
     void setPC(const uint16_t addr);
     uint8_t getMemTag(const uint16_t addr);
+
+    const bool getOption(const int option);
+    void setOption(const int option, const bool value);
+    void toggleOption(const int option);
 }
\ No newline at end of file
diff --git a/z80analyze.cpp b/z80analyze.cpp
new file mode 100644
index 0000000..996531b
--- /dev/null
+++ b/z80analyze.cpp
@@ -0,0 +1,43 @@
+#include "z80analyze.h"
+#include "z80.h"
+#include <SDL2/SDL.h>
+
+namespace z80analyze
+{
+    SDL_Window *win = nullptr;
+    SDL_Renderer *ren = nullptr;
+    SDL_Texture *tex = nullptr;
+
+    void show()
+    {
+        if (!win)
+        {
+            win = SDL_CreateWindow("Z80 Analyzer", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 256, 256, SDL_WINDOW_SHOWN);
+            ren = SDL_CreateRenderer(win, -1, 0);
+            tex = SDL_CreateTexture(ren, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, 256, 256);
+        }
+        refresh();
+    }
+
+    void refresh()
+    {
+        Uint32 *pixels;
+        int pitch;
+        SDL_LockTexture(tex, NULL, (void**)&pixels, &pitch);
+        for (int i=0; i<65536; ++i)
+        {
+            uint8_t tag = z80::getMemTag(i);
+            pixels[i] = tag==MEMTAG_NONE ? 0x808080 : tag==MEMTAG_DATA ? 0x0000FF : 0x00FF00;
+        }
+        SDL_UnlockTexture(tex);
+        SDL_RenderCopy(ren, tex, NULL, NULL);
+        SDL_RenderPresent(ren);
+    }
+
+    void hide()
+    {
+        SDL_DestroyTexture(tex);
+        SDL_DestroyRenderer(ren);
+        SDL_DestroyWindow(win);
+    }
+}
diff --git a/z80analyze.h b/z80analyze.h
new file mode 100644
index 0000000..b5a93b6
--- /dev/null
+++ b/z80analyze.h
@@ -0,0 +1,8 @@
+#pragma once
+
+namespace z80analyze
+{
+    void show();
+    void refresh();
+    void hide();
+}
diff --git a/zx_screen.cpp b/zx_screen.cpp
index 4f3f049..2adfa1f 100644
--- a/zx_screen.cpp
+++ b/zx_screen.cpp
@@ -181,7 +181,7 @@ namespace zxscreen
 
     void redraw(const bool present)
     {
-        if (zx_tape::getplaying() && zx_tape::getberserk()) return;
+        if (zx_tape::getplaying() && zx_tape::getOption(ZXTAPE_OPTION_FAST_LOAD)) return;
 
         Uint32* pixels;
         int pitch;
diff --git a/zx_tape.cpp b/zx_tape.cpp
index 895dfdf..2888446 100644
--- a/zx_tape.cpp
+++ b/zx_tape.cpp
@@ -1,6 +1,7 @@
 #include "zx_tape.h"
 #include "zx_ula.h"
 #include "zx_screen.h"
+#include "z80debug.h"
 #include <vector>
 #include <stdio.h>
 #include <stdlib.h>
@@ -34,7 +35,7 @@ namespace zx_tape
 
     bool playing = false;
     bool loaded = false;
-    bool berserk_mode = true;
+    bool options[ZXTAPE_NUM_OPTIONS] = { true, true };
 
     std::vector<block_t> blocks;
     uint8_t current_block = 0;
@@ -80,7 +81,7 @@ namespace zx_tape
     void stop()
     {
         playing = false;
-        berserk_mode = false;
+        //berserk_mode = false;
     }
 
     void rewind()
@@ -220,6 +221,7 @@ namespace zx_tape
                     printf("end\n");
                     stop();
                     rewind();
+                    if (options[ZXTAPE_OPTION_STOP_AT_END]) z80debug::stop();
                 }
                 else
                 {
@@ -232,8 +234,6 @@ namespace zx_tape
         zx_ula::set_ear(pulse_level);
     }
 
-    void setberserk(const bool value) { berserk_mode = value; }
-    const bool getberserk() { return berserk_mode; }
     const bool getplaying() { return playing; }
 
     void report()
@@ -242,4 +242,19 @@ namespace zx_tape
         const int percent = (float(block_pos)/float(blocks[current_block].length))*100;
         printf("tape loading: %i%\n", percent);
     }
+
+    const bool getOption(const int option)
+    {
+        return options[option];
+    }
+
+    void setOption(const int option, const bool value)
+    {
+        options[option] = value;
+    }
+
+    void toggleOption(const int option)
+    {
+        options[option] = !options[option];
+    }
 }
diff --git a/zx_tape.h b/zx_tape.h
index 50e39e5..d9a9122 100644
--- a/zx_tape.h
+++ b/zx_tape.h
@@ -3,13 +3,19 @@
 
 namespace zx_tape
 {
+    #define ZXTAPE_OPTION_FAST_LOAD      0
+    #define ZXTAPE_OPTION_STOP_AT_END    1
+    #define ZXTAPE_NUM_OPTIONS          2
+
     void load(const char* filename);
     void play();
     void stop();
     void rewind();
     void update(const uint8_t dt);
-    void setberserk(const bool value);
-    const bool getberserk();
     const bool getplaying();
     void report();
+
+    const bool getOption(const int option);
+    void setOption(const int option, const bool value);
+    void toggleOption(const int option);
 }