diff --git a/grbl_machine.cpp b/grbl_machine.cpp
index 884aac9..d75f1de 100644
--- a/grbl_machine.cpp
+++ b/grbl_machine.cpp
@@ -373,16 +373,25 @@ std::string grbl::setting_description(int number) {
         case 75:
             return "Bluetooth service ()\nBluetooth service name.";
 
-        case 80: return "Spindle P-gain";
-        case 81: return "Spindle I-gain";
-        case 82: return "Spindle D-gain";
-        case 84: return "Spindle PID max error";
-        case 85: return "Spindle PID max I error\nSpindle PID max integrator error";
+        case 80:
+            return "Spindle P-gain";
+        case 81:
+            return "Spindle I-gain";
+        case 82:
+            return "Spindle D-gain";
+        case 84:
+            return "Spindle PID max error";
+        case 85:
+            return "Spindle PID max I error\nSpindle PID max integrator error";
 
-        case 90: return "Spindle sync P-gain";
-        case 91: return "Spindle sync I-gain";
-        case 92: return "Spindle sync D-gain";
-        case 95: return "Spindle sync PID max I error\nSpindle sync PID max integrator error";
+        case 90:
+            return "Spindle sync P-gain";
+        case 91:
+            return "Spindle sync I-gain";
+        case 92:
+            return "Spindle sync D-gain";
+        case 95:
+            return "Spindle sync PID max I error\nSpindle sync PID max integrator error";
 
         case 100:
             return "X-axis travel resolution (step/mm)\nX-axis travel resolution in steps per millimeter.";
@@ -609,6 +618,30 @@ const std::map<std::string, std::string, grbl::parameters_cmp>& grbl::machine::g
     return parameters;
 }
 
+void grbl::machine::zero_offset(int which) {
+    while (awaiting_responses > 0);
+    pipe->send("G10 L20 P" + std::to_string(1 + which) + " X0 Y0 Z0"); // P1 => G54
+    awaiting_responses++;
+    while (awaiting_responses > 0);
+
+    pipe->send("$#");
+    awaiting_responses++;
+    while (awaiting_responses > 0);
+    listener->on_parameters_reloaded();
+}
+
+void grbl::machine::zero_offset_axis(int offset_index, int axis) {
+    while (awaiting_responses > 0);
+    pipe->send("G10 L20 P" + std::to_string(1 + offset_index) + " " + char('X' + axis) + "0"); // P1 => G54
+    awaiting_responses++;
+    while (awaiting_responses > 0);
+
+    pipe->send("$#");
+    awaiting_responses++;
+    while (awaiting_responses > 0);
+    listener->on_parameters_reloaded();
+}
+
 bool grbl::jog_state::no_jogging() const {
     return !(up_pressed || down_pressed || left_pressed || right_pressed || z_up_pressed || z_down_pressed);
 }
@@ -678,7 +711,7 @@ void grbl::machine_state_init::move_to_next_init_stage() {
     switch (init_state) {
         case init_stage::start:
             init_state = init_stage::set_work_pos;
-            cnc->pipe->send("$10=0");
+            cnc->pipe->send("$10=1"); // machine pos in report, please
             break;
         case init_stage::set_work_pos:
             init_state = init_stage::fetch_settings;
@@ -714,18 +747,31 @@ void grbl::machine_state_idle::on_exit(grbl::machine *m) {
 
 void grbl::machine_state_idle::on_line_received(std::string line) {
     if (starts_with(line, "ok")) {
+        if (cnc->awaiting_responses > 0) {
+            cnc->awaiting_responses--;
+        }
     } else if (starts_with(line, "error")) {
+        if (cnc->awaiting_responses > 0) {
+            cnc->awaiting_responses--;
+        }
     } else if (starts_with(line, "Grbl")) {
         cnc->listener->on_banner(line);
         cnc->reset_machine_state();
     } else if (starts_with(line, "<")) {
         cnc->last_report = parse_status_report(line, cnc->last_report);
         cnc->listener->on_realtime_status_report(cnc->last_report);
-
     } else if (starts_with(line, "[MSG:")) {
         cnc->listener->on_message(line.substr(5, line.size() - 6));
     } else if (starts_with(line, "ALARM:")) {
         cnc->listener->on_alarm(std::stoi(line.substr(6)));
+    } else if (starts_with(line, "$")) {
+        auto pieces = split_string(line, "=");
+        cnc->settings[pieces[0]] = pieces[1];
+    } else if (starts_with(line, "[G") || starts_with(line, "[H") || starts_with(line, "[T") || starts_with(line, "[P")) {
+        line = line.substr(1, line.size() - 2);
+        // TODO: some parameters have more than two :
+        auto pieces = split_string(line, ":");
+        cnc->parameters[pieces[0]] = pieces[1];
     }
 }
 
diff --git a/grbl_machine.h b/grbl_machine.h
index 01a1a03..c11f2a6 100644
--- a/grbl_machine.h
+++ b/grbl_machine.h
@@ -112,6 +112,8 @@ struct machine_listener {
     virtual void on_init_completed() = 0;
     virtual void on_run_completed(bool success, size_t failed_index, size_t error) = 0;
     virtual void on_check_completed(bool success, size_t failed_index, size_t error) = 0;
+    virtual void on_settings_reloaded() = 0;
+    virtual void on_parameters_reloaded() = 0;
 };
 
 
@@ -210,10 +212,14 @@ struct machine : public transport_callbacks {
     void request_unlock();
     void request_home();
     void request_reset();
-
     void request_cycle_start();
     void request_feed_hold();
 
+    // 0 = G54, 1 = G55, etc
+    void zero_offset(int which);
+
+    // 0 = G54, 1 = G55, etc axis 0=X, 1=Y, 2=Z
+    void zero_offset_axis(int offset_index, int axis);
 
 protected:
     void on_connected(transport *transport) override;
@@ -232,6 +238,7 @@ protected:
     std::map<std::string, std::string, settings_cmp> settings;
     std::map<std::string, std::string, parameters_cmp> parameters;
 
+    volatile size_t awaiting_responses = 0;
     realtime_status_report last_report{};
     machine_listener *listener = nullptr;
     transport *pipe = nullptr;
diff --git a/main.cpp b/main.cpp
index a5cee6a..e51f97c 100644
--- a/main.cpp
+++ b/main.cpp
@@ -51,7 +51,6 @@ public:
 
     Window *window;
     grbl::jog_state jog;
-    Label *m_pos_x, *m_pos_y, *m_pos_z;
     TextArea *lblStatus, *lblSubstatus;
     nanogui::Color colRed = nanogui::Color(255, 0, 0, 255);
     nanogui::Color colGreen = nanogui::Color(0, 255, 0, 255);
@@ -60,7 +59,6 @@ public:
     grbl::program pgm;
     Button *btnLoadProgram, *btnCheckProgram, *btnRunProgram;
 
-
     grbl::program_renderer renderer;
 
     glm::vec3 cam_target = glm::vec3(0);
@@ -74,66 +72,10 @@ public:
     VScrollPanel *parameters_vscroll;
     Widget *parameters_layer;
     TextBox *mpos_x_text, *mpos_y_text, *mpos_z_text;
-
-    void fill_in_settings() {
-        settings_vscroll = new VScrollPanel(tab_widget);
-        tab_widget->append_tab("Settings", settings_vscroll);
-
-        settings_layer = new Widget(settings_vscroll);
-        settings_layer->set_layout(new GridLayout(Orientation::Horizontal, 1, Alignment::Middle));
-
-        auto& settings = cnc.get_settings();
-
-        for (auto& s: settings) {
-            auto w = settings_layer->add<Widget>();
-            w->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 2, 2));
-            auto x = w->add<Label>(s.first, "sans-bold", 20);
-            x->set_fixed_width(40);
-
-            auto desc = grbl::setting_description(std::stoi(s.first.substr(1)));
-
-            auto y = w->add<TextBox>(s.second);
-            y->set_editable(true);
-            y->set_tooltip(desc);
-            y->set_fixed_width(200);
-
-            auto z = w->add<ToolButton>(FA_SAVE);
-            z->set_flags(Button::Flags::NormalButton); // no toggle, please
-            z->set_tooltip("save");
-
-            auto t = w->add<TextArea>();
-            t->set_fixed_width(200);
-            t->set_fixed_height(20);
-            t->clear();
-            t->append(desc.substr(0, desc.find_first_of('\n')));
-        }
-    }
-
-    void fill_in_parameters() {
-        parameters_vscroll = new VScrollPanel(tab_widget);
-        tab_widget->append_tab("Parameters", parameters_vscroll);
-
-        parameters_layer = new Widget(parameters_vscroll);
-        parameters_layer->set_layout(new GridLayout(Orientation::Horizontal, 1, Alignment::Middle));
-
-        auto& parameters = cnc.get_parameters();
-
-        for (auto& entry: parameters) {
-            auto w = parameters_layer->add<Widget>();
-            w->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 2, 2));
-            auto x = w->add<Label>(entry.first, "sans-bold", 20);
-            x->set_fixed_width(50);
-
-            auto y = w->add<TextBox>(entry.second);
-            y->set_editable(true);
-            y->set_fixed_width(200);
-
-            auto z = w->add<ToolButton>(FA_SAVE);
-            z->set_flags(Button::Flags::NormalButton); // no toggle, please
-            z->set_tooltip("save");
-        }
-    }
-
+    ComboBox *cboOffset, *cboTool;
+    float offset_x = 0;
+    float offset_y = 0;
+    float offset_z = 0;
 
     SenderApp() : Screen(Vector2i(1024, 768), "GRBL Sender") {
         inc_ref();
@@ -162,77 +104,107 @@ public:
         layer->set_layout(new GroupLayout());
         tab_widget->append_tab("Info", layer);
 
-//        Widget *layer3 = new Widget(tab_widget);
-//        tab_widget->append_tab("Offsets", layer3);
-//        layer3->set_layout(new GroupLayout());
-//        layer3->add<Label>("Parameters");
-//        layer3->add<TextBox>();
-
-
         new Label(layer, "Status", "sans-bold");
         Widget *status_holder = new Widget(layer);
         status_holder->set_layout(new GridLayout());
 
-        lblStatus = new TextArea(layer);
+        lblStatus = layer->add<TextArea>();
         lblStatus->set_fixed_height(20);
         lblStatus->set_font("sans");
 
-        lblSubstatus = new TextArea(layer);
+        lblSubstatus = layer->add<TextArea>();
         lblSubstatus->set_font("sans");
         lblSubstatus->set_fixed_height(50);
 
-        // Machine pos
-        layer->add<Label>("Machine pos", "sans-bold");
+        // DRO
+        layer->add<Label>("DRO", "sans-bold", 20);
         Widget *mpos = new Widget(layer);
-        mpos->set_layout(new GridLayout(Orientation::Horizontal, 1, Alignment::Middle));
+        mpos->set_layout(new GridLayout(Orientation::Horizontal, 1, Alignment::Middle, 0, 6));
 
         auto x_holder = mpos->add<Widget>();
-        x_holder->set_layout(new BoxLayout(Orientation::Horizontal));
-        auto lbl = x_holder->add<Label>("X");
-        lbl->set_font_size(20);
-        lbl->set_fixed_width(50);
-        mpos_x_text = x_holder->add<TextBox>(std::to_string(cnc.get_status().work_pos[0]));
+        x_holder->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 0, 6));
+        auto lbl = x_holder->add<Label>("X", "sans-bold", 20);
+        lbl->set_fixed_width(30);
+        mpos_x_text = x_holder->add<TextBox>(std::to_string(cnc.get_status().machine_pos[0]));
         mpos_x_text->set_fixed_width(200);
+        auto zero_btn = x_holder->add<ToolButton>(FA_BAN);
+        zero_btn->set_flags(Button::Flags::NormalButton);
+        zero_btn->set_tooltip("Zero axis");
+        zero_btn->set_callback([&]() {
+            cnc.zero_offset_axis(cboOffset->selected_index(), 0);
+        });
 
         auto y_holder = mpos->add<Widget>();
-        y_holder->set_layout(new BoxLayout(Orientation::Horizontal));
-        lbl = y_holder->add<Label>("Y");
-        lbl->set_font_size(20);
-        lbl->set_fixed_width(50);
-        mpos_y_text = y_holder->add<TextBox>(std::to_string(cnc.get_status().work_pos[1]));
+        y_holder->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 0, 6));
+        lbl = y_holder->add<Label>("Y", "sans-bold", 20);
+        lbl->set_fixed_width(30);
+        mpos_y_text = y_holder->add<TextBox>(std::to_string(cnc.get_status().machine_pos[1]));
         mpos_y_text->set_fixed_width(200);
+        zero_btn = y_holder->add<ToolButton>(FA_BAN);
+        zero_btn->set_flags(Button::Flags::NormalButton);
+        zero_btn->set_tooltip("Zero axis");
+        zero_btn->set_callback([&]() {
+            cnc.zero_offset_axis(cboOffset->selected_index(), 1);
+        });
 
         auto z_holder = mpos->add<Widget>();
-        z_holder->set_layout(new BoxLayout(Orientation::Horizontal));
-        lbl = z_holder->add<Label>("Z");
-        lbl->set_font_size(20);
-        lbl->set_fixed_width(50);
-        mpos_z_text = z_holder->add<TextBox>(std::to_string(cnc.get_status().work_pos[0]));
+        z_holder->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 0, 6));
+        lbl = z_holder->add<Label>("Z", "sans-bold", 20);
+        lbl->set_fixed_width(30);
+        mpos_z_text = z_holder->add<TextBox>(std::to_string(cnc.get_status().machine_pos[0]));
         mpos_z_text->set_fixed_width(200);
+        zero_btn = z_holder->add<ToolButton>(FA_BAN);
+        zero_btn->set_flags(Button::Flags::NormalButton);
+        zero_btn->set_tooltip("Zero axis");
+        zero_btn->set_callback([&]() {
+            cnc.zero_offset_axis(cboOffset->selected_index(), 2);
+        });
+
+        auto zero_all_btn = mpos->add<Button>("Zero all");
+        zero_all_btn->set_callback([&]() {
+            cnc.zero_offset(cboOffset->selected_index());
+        });
+
+        // work parameters
+        layer->add<Label>("Work parameters", "sans-bold", 20);
+        auto x = new Widget(layer);
+        x->set_layout(new GridLayout(Orientation::Horizontal, 4, Alignment::Middle, 0, 6));
+
+        x->add<Label>("Offset:");
+        std::vector<std::string> offset_items = {"G54", "G55", "G56", "G57", "G58", "G59"};
+        cboOffset = x->add<ComboBox>(offset_items);
+        cboOffset->set_callback([&](int idx) {
+            refresh_offset();
+            update_dro();
+        });
+
+        x->add<Label>("Tool:");
+        std::vector<std::string> tool_items = {"None"};
+        cboTool = x->add<ComboBox>(tool_items);
 
         // buttons to change state
         new Label(layer, "Actions", "sans-bold");
-        Widget *actions = new Widget(layer);
+        auto *actions = new Widget(layer);
         actions->set_layout(new BoxLayout(Orientation::Horizontal));
 
-        Button *btnUnlock = new Button(actions, "Unlock");
+        auto *btnUnlock = new Button(actions, "Unlock");
         btnUnlock->set_callback([&] {
             cnc.request_unlock();
         });
-        Button *btnHome = new Button(actions, "Home");
+        auto *btnHome = new Button(actions, "Home");
         btnHome->set_callback([&] {
             cnc.request_home();
         });
-        Button *btnReset = new Button(actions, "Reset");
+        auto *btnReset = new Button(actions, "Reset");
         btnReset->set_background_color(colRed);
         btnReset->set_callback([&] {
             cnc.request_reset();
         });
-        Button *btnCycleStart = new Button(actions, "Cycle Start");
+        auto *btnCycleStart = new Button(actions, "Cycle Start");
         btnCycleStart->set_callback([&] {
             cnc.request_cycle_start();
         });
-        Button *btnFeedHold = new Button(actions, "Feed Hold");
+        auto *btnFeedHold = new Button(actions, "Feed Hold");
         btnFeedHold->set_callback([&] {
             cnc.request_feed_hold();
         });
@@ -280,68 +252,83 @@ public:
         });
         btnRunProgram->set_tooltip("Execute program");
 
-
-//        // Alternative construction notation using variadic template
-//        btnLoadProgram = window->add<Button>("Styled", FA_ROCKET);
-//        btnLoadProgram->set_background_color(Color(0, 0, 255, 25));
-//        btnLoadProgram->set_callback([] { std::cout << "pushed!" << std::endl; });
-//        btnLoadProgram->set_tooltip("This button has a fairly long tooltip. It is so long, in "
-//                                    "fact, that the shown text will span several lines.");
-//
-//        new Label(window, "Toggle buttons", "sans-bold");
-//        btnLoadProgram = new Button(window, "Toggle me");
-//        btnLoadProgram->set_flags(Button::ToggleButton);
-//        btnLoadProgram->set_change_callback([](bool state) { std::cout << "Toggle button state: " << state << std::endl; });
-//
-//        new Label(window, "Radio buttons", "sans-bold");
-//        btnLoadProgram = new Button(window, "Radio button 1");
-//        btnLoadProgram->set_flags(Button::RadioButton);
-//        btnLoadProgram = new Button(window, "Radio button 2");
-//        btnLoadProgram->set_flags(Button::RadioButton);
-//
-//        new Label(window, "A tool palette", "sans-bold");
-//        Widget *tools = new Widget(window);
-//        tools->set_layout(new BoxLayout(Orientation::Horizontal,
-//                                        Alignment::Middle, 0, 6));
-//
-//        btnLoadProgram = new ToolButton(tools, FA_CLOUD);
-//        btnLoadProgram = new ToolButton(tools, FA_FAST_FORWARD);
-//        btnLoadProgram = new ToolButton(tools, FA_COMPASS);
-//        btnLoadProgram = new ToolButton(tools, FA_UTENSILS);
-//
-//        new Label(window, "Popup buttons", "sans-bold");
-//        PopupButton *popup_btn = new PopupButton(window, "Popup", FA_FLASK);
-//        Popup *popup = popup_btn->popup();
-//        popup->set_layout(new GroupLayout());
-//        new Label(popup, "Arbitrary widgets can be placed here");
-//        new CheckBox(popup, "A check box");
-//        // popup right
-//        popup_btn = new PopupButton(popup, "Recursive popup", FA_CHART_PIE);
-//        Popup *popup_right = popup_btn->popup();
-//        popup_right->set_layout(new GroupLayout());
-//        new CheckBox(popup_right, "Another check box");
-//        // popup left
-//        popup_btn = new PopupButton(popup, "Recursive popup", FA_DNA);
-//        popup_btn->set_side(Popup::Side::Left);
-//        Popup *popup_left = popup_btn->popup();
-//        popup_left->set_layout(new GroupLayout());
-//        new CheckBox(popup_left, "Another check box");
-
         perform_layout();
 
-//           All NanoGUI widgets are initialized at this point. Now
-//           create shaders to draw the main window contents.
-//
-//           NanoGUI comes with a simple wrapper around OpenGL 3, which
-//           eliminates most of the tedious and error-prone shader and buffer
-//           object management.
-
         m_render_pass = new RenderPass({this});
         m_render_pass->set_clear_color(0, Color(0.3f, 0.3f, 0.32f, 1.f));
         m_render_pass->set_depth_test(RenderPass::DepthTest::Always, true);
         m_render_pass->set_cull_mode(RenderPass::CullMode::Disabled);
     }
 
+    void refresh_offset() {
+        auto offset_name = "G" + std::to_string(cboOffset->selected_index() + 54);
+        auto offset_values = cnc.get_parameters().at(offset_name);
+        auto offset_pieces = split_string(offset_values, ",");
+        offset_x = std::stof(offset_pieces[0]);
+        offset_y = std::stof(offset_pieces[1]);
+        offset_z = std::stof(offset_pieces[2]);
+    }
+
+    void fill_in_parameters() {
+        parameters_vscroll = new VScrollPanel(tab_widget);
+        tab_widget->append_tab("Parameters", parameters_vscroll);
+
+        parameters_layer = new Widget(parameters_vscroll);
+        parameters_layer->set_layout(new GridLayout(Orientation::Horizontal, 1, Alignment::Middle));
+
+        auto& parameters = cnc.get_parameters();
+
+        for (auto& entry: parameters) {
+            auto w = parameters_layer->add<Widget>();
+            w->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 2, 2));
+            auto x = w->add<Label>(entry.first, "sans-bold", 20);
+            x->set_fixed_width(50);
+
+            auto y = w->add<TextBox>(entry.second);
+            y->set_editable(true);
+            y->set_fixed_width(200);
+
+            auto z = w->add<ToolButton>(FA_SAVE);
+            z->set_flags(Button::Flags::NormalButton); // no toggle, please
+            z->set_tooltip("save");
+        }
+    }
+
+
+    void fill_in_settings() {
+        settings_vscroll = new VScrollPanel(tab_widget);
+        tab_widget->append_tab("Settings", settings_vscroll);
+
+        settings_layer = new Widget(settings_vscroll);
+        settings_layer->set_layout(new GridLayout(Orientation::Horizontal, 1, Alignment::Middle));
+
+        auto& settings = cnc.get_settings();
+
+        for (auto& s: settings) {
+            auto w = settings_layer->add<Widget>();
+            w->set_layout(new BoxLayout(Orientation::Horizontal, Alignment::Middle, 2, 2));
+            auto x = w->add<Label>(s.first, "sans-bold", 20);
+            x->set_fixed_width(40);
+
+            auto desc = grbl::setting_description(std::stoi(s.first.substr(1)));
+
+            auto y = w->add<TextBox>(s.second);
+            y->set_editable(true);
+            y->set_tooltip(desc);
+            y->set_fixed_width(200);
+
+            auto z = w->add<ToolButton>(FA_SAVE);
+            z->set_flags(Button::Flags::NormalButton); // no toggle, please
+            z->set_tooltip("save");
+
+            auto t = w->add<TextArea>();
+            t->set_fixed_width(200);
+            t->set_fixed_height(20);
+            t->clear();
+            t->append(desc.substr(0, desc.find_first_of('\n')));
+        }
+    }
+
     void init_program_geometry() {
         renderer.update(pgm, cnc);
 
@@ -363,16 +350,26 @@ public:
     void on_disconnected() override {
     }
 
+    void on_settings_reloaded() override {
+    }
+
+    void on_parameters_reloaded() override {
+        refresh_offset();
+        update_dro();
+    }
+
 
     grbl::realtime_status_report last_report;
 
     void on_init_completed() override {
         fill_in_settings();
         fill_in_parameters();
+        refresh_offset();
+        update_dro();
     }
 
     void on_realtime_status_report(grbl::realtime_status_report report) override {
-        if (report == last_report) return;
+//        if (report == last_report) return;
 
         if (last_report.status != report.status) {
             lblStatus->clear();
@@ -386,14 +383,16 @@ public:
             }
         }
 
-
-        mpos_x_text->set_value(std::to_string(cnc.get_status().work_pos[0]));
-        mpos_y_text->set_value(std::to_string(cnc.get_status().work_pos[1]));
-        mpos_z_text->set_value(std::to_string(cnc.get_status().work_pos[2]));
-
+        update_dro();
         last_report = report;
     }
 
+    void update_dro() {
+        mpos_x_text->set_value(std::to_string(cnc.get_status().machine_pos[0] - offset_x));
+        mpos_y_text->set_value(std::to_string(cnc.get_status().machine_pos[1] - offset_y));
+        mpos_z_text->set_value(std::to_string(cnc.get_status().machine_pos[2] - offset_z));
+    }
+
     void on_banner(std::string line) override {
     }