diff --git a/papers/doc/7-systems/fds.md b/papers/doc/7-systems/fds.md
new file mode 100644
index 00000000..ee288198
--- /dev/null
+++ b/papers/doc/7-systems/fds.md
@@ -0,0 +1,26 @@
+# Famicom Disk System
+
+the Famicom Disk System is an expansion device for the Famicom (known as NES outside Japan), a popular console from the '80's.
+as it name implies, it allowed people to play games on specialized floppy disks that could be rewritten on vending machines, therefore reducing the cost of ownership and manufacturing.
+
+it also offers an additional wavetable sound channel with (somewhat limited) FM capabilities, which is what Furnace supports.
+
+# effects
+
+- `10xx`: change wave.
+- `11xx`: set modulation depth.
+- `12xy`: set modulation speed high byte and toggle on/off.
+  - `x` is the toggle. a value of 1 turns on the modulator.
+  - `y` is the speed.
+- `13xx`: set modulation speed low byte.
+- `14xx`: set modulator position.
+- `15xx`: set modulator wave.
+  - `xx` points to a wavetable. it should (preferably) have a height of 7 with the values mapping to:
+    - 0: +0
+    - 1: +1
+    - 2: +2
+    - 3: +3
+    - 4: reset
+    - 5: -3
+    - 6: -2
+    - 7: -1
diff --git a/src/engine/platform/fds.cpp b/src/engine/platform/fds.cpp
index b4103748..ede447df 100644
--- a/src/engine/platform/fds.cpp
+++ b/src/engine/platform/fds.cpp
@@ -63,10 +63,10 @@ const char* DivPlatformFDS::getEffectName(unsigned char effect) {
       return "11xx: Set modulation depth";
       break;
     case 0x12:
-      return "12xy: Set modulation frequency high byte (x: enable; y: value)";
+      return "12xy: Set modulation speed high byte (x: enable; y: value)";
       break;
     case 0x13:
-      return "13xx: Set modulation frequency low byte";
+      return "13xx: Set modulation speed low byte";
       break;
     case 0x14:
       return "14xx: Set modulator position";
@@ -163,6 +163,22 @@ void DivPlatformFDS::tick() {
         //if (!chan[i].keyOff) chan[i].keyOn=true;
       }
     }
+    if (chan[i].std.hadEx1) { // mod depth
+      chan[i].modOn=chan[i].std.ex1;
+      chan[i].modDepth=chan[i].std.ex1;
+      rWrite(0x4084,(chan[i].modOn<<7)|0x40|chan[i].modDepth);
+    }
+    if (chan[i].std.hadEx2) { // mod speed
+      chan[i].modFreq=chan[i].std.ex2;
+      rWrite(0x4086,chan[i].modFreq&0xff);
+      rWrite(0x4087,chan[i].modFreq>>8);
+    }
+    if (chan[i].std.hadEx3) { // mod position
+      chan[i].modPos=chan[i].std.ex3;
+      rWrite(0x4087,0x80|chan[i].modFreq>>8);
+      rWrite(0x4085,chan[i].modPos);
+      rWrite(0x4087,chan[i].modFreq>>8);
+    }
     if (chan[i].sweepChanged) {
       chan[i].sweepChanged=false;
       if (i==0) {
@@ -199,6 +215,42 @@ int DivPlatformFDS::dispatch(DivCommand c) {
         chan[c.chan].freqChanged=true;
         chan[c.chan].note=c.value;
       }
+      if (chan[c.chan].insChanged) {
+        DivInstrument* ins=parent->getIns(chan[c.chan].ins);
+        if (ins->fds.initModTableWithFirstWave) { // compatible
+          if (chan[c.chan].wave==-1) {
+            DivWavetable* wt=parent->getWave(0);
+            for (int i=0; i<32; i++) {
+              if (wt->max<1 || wt->len<1) {
+                rWrite(0x4040+i,0);
+              } else {
+                int data=wt->data[i*MIN(32,wt->len)/32]*7/wt->max;
+                if (data<0) data=0;
+                if (data>7) data=7;
+                chan[c.chan].modTable[i]=data;
+              }
+            }
+            rWrite(0x4087,0x80|chan[c.chan].modFreq>>8);
+            for (int i=0; i<32; i++) {
+              rWrite(0x4088,chan[c.chan].modTable[i]);
+            }
+            rWrite(0x4087,chan[c.chan].modFreq>>8);
+          }
+        } else { // The Familiar Way
+          chan[c.chan].modDepth=ins->fds.modDepth;
+          chan[c.chan].modOn=ins->fds.modDepth;
+          chan[c.chan].modFreq=ins->fds.modSpeed;
+          rWrite(0x4084,(chan[c.chan].modOn<<7)|0x40|chan[c.chan].modDepth);
+          rWrite(0x4086,chan[c.chan].modFreq&0xff);
+
+          rWrite(0x4087,0x80|chan[c.chan].modFreq>>8);
+          for (int i=0; i<32; i++) {
+            chan[c.chan].modTable[i]=ins->fds.modTable[i]&7;
+            rWrite(0x4088,chan[c.chan].modTable[i]);
+          }
+          rWrite(0x4087,chan[c.chan].modFreq>>8);
+        }
+      }
       chan[c.chan].active=true;
       chan[c.chan].keyOn=true;
       chan[c.chan].std.init(parent->getIns(chan[c.chan].ins));
@@ -256,7 +308,9 @@ int DivPlatformFDS::dispatch(DivCommand c) {
       break;
     case DIV_CMD_FDS_MOD_POS:
       chan[c.chan].modPos=c.value&0x7f;
-      // TODO
+      rWrite(0x4087,0x80|chan[c.chan].modFreq>>8);
+      rWrite(0x4085,chan[c.chan].modPos);
+      rWrite(0x4087,chan[c.chan].modFreq>>8);
       break;
     case DIV_CMD_FDS_MOD_WAVE: {
       DivWavetable* wt=parent->getWave(c.value);
diff --git a/src/gui/insEdit.cpp b/src/gui/insEdit.cpp
index d626a6b7..8ddbcbe3 100644
--- a/src/gui/insEdit.cpp
+++ b/src/gui/insEdit.cpp
@@ -2116,8 +2116,11 @@ void FurnaceGUI::drawInsEdit() {
           ImGui::EndTabItem();
         }
         if (ins->type==DIV_INS_FDS) if (ImGui::BeginTabItem("FDS")) {
-          ImGui::Text("FDS config goes here");
-          ImGui::Checkbox("Initialize modulation table with first wavetable (compatibility)",&ins->fds.initModTableWithFirstWave);
+          float modTable[32];
+          ImGui::Checkbox("Compatibility mode",&ins->fds.initModTableWithFirstWave);
+          if (ImGui::IsItemHovered()) {
+            ImGui::SetTooltip("only use for compatibility with .dmf modules!\n- initializes modulation table with first wavetable\n- does not alter modulation parameters on instrument change");
+          }
           if (ImGui::InputInt("Modulation depth",&ins->fds.modDepth,1,32)) {
             if (ins->fds.modDepth<0) ins->fds.modDepth=0;
             if (ins->fds.modDepth>63) ins->fds.modDepth=63;
@@ -2127,6 +2130,26 @@ void FurnaceGUI::drawInsEdit() {
             if (ins->fds.modSpeed>4095) ins->fds.modSpeed=4095;
           }
           ImGui::Text("Modulation table");
+          for (int i=0; i<32; i++) {
+            modTable[i]=ins->fds.modTable[i];
+          }
+          ImVec2 modTableSize=ImVec2(ImGui::GetContentRegionAvail().x,96.0f*dpiScale);
+          PlotCustom("ModTable",modTable,32,0,NULL,-4,3,modTableSize,sizeof(float),ImVec4(1.0f,1.0f,1.0f,1.0f),0,NULL,true);
+          if (ImGui::IsItemClicked(ImGuiMouseButton_Left)) {
+            macroDragStart=ImGui::GetItemRectMin();
+            macroDragAreaSize=modTableSize;
+            macroDragMin=-4;
+            macroDragMax=3;
+            macroDragBitOff=0;
+            macroDragBitMode=false;
+            macroDragInitialValueSet=false;
+            macroDragInitialValue=false;
+            macroDragLen=32;
+            macroDragActive=true;
+            macroDragCTarget=(unsigned char*)ins->fds.modTable;
+            macroDragChar=true;
+            processDrags(ImGui::GetMousePos().x,ImGui::GetMousePos().y); \
+          }
           ImGui::EndTabItem();
         }
         if (ImGui::BeginTabItem("Macros")) {
@@ -2268,6 +2291,10 @@ void FurnaceGUI::drawInsEdit() {
             ex1Max=252;
             ex2Max=2;
           }
+          if (ins->type==DIV_INS_FDS) {
+            ex1Max=63;
+            ex2Max=4095;
+          }
           if (ins->type==DIV_INS_SAA1099) ex1Max=8;
 
           if (settings.macroView==0) { // modern view
@@ -2296,6 +2323,8 @@ void FurnaceGUI::drawInsEdit() {
                 NORMAL_MACRO(ins->std.ex1Macro,ins->std.ex1MacroLen,ins->std.ex1MacroLoop,ins->std.ex1MacroRel,0,ex1Max,"ex1","Envelope Mode",160,ins->std.ex1MacroOpen,true,x1_010EnvBits,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[4],0,ex1Max,NULL,false);
               } else if (ins->type==DIV_INS_N163) {
                 NORMAL_MACRO(ins->std.ex1Macro,ins->std.ex1MacroLen,ins->std.ex1MacroLoop,ins->std.ex1MacroRel,0,ex1Max,"ex1","Waveform len.",160,ins->std.ex1MacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[4],0,ex1Max,NULL,false);
+              } else if (ins->type==DIV_INS_FDS) {
+                NORMAL_MACRO(ins->std.ex1Macro,ins->std.ex1MacroLen,ins->std.ex1MacroLoop,ins->std.ex1MacroRel,0,ex1Max,"ex1","Mod Depth",160,ins->std.ex1MacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[4],0,ex1Max,NULL,false);
               } else {
                 NORMAL_MACRO(ins->std.ex1Macro,ins->std.ex1MacroLen,ins->std.ex1MacroLoop,ins->std.ex1MacroRel,0,ex1Max,"ex1","Duty",160,ins->std.ex1MacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[4],0,ex1Max,NULL,false);
               }
@@ -2305,6 +2334,8 @@ void FurnaceGUI::drawInsEdit() {
                 NORMAL_MACRO(ins->std.ex2Macro,ins->std.ex2MacroLen,ins->std.ex2MacroLoop,ins->std.ex2MacroRel,0,ex2Max,"ex2","Resonance",64,ins->std.ex2MacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[5],0,ex2Max,NULL,false);
               } else if (ins->type==DIV_INS_N163) {
                 NORMAL_MACRO(ins->std.ex2Macro,ins->std.ex2MacroLen,ins->std.ex2MacroLoop,ins->std.ex2MacroRel,0,ex2Max,"ex2","Waveform update",64,ins->std.ex2MacroOpen,true,n163UpdateBits,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[5],0,ex2Max,NULL,false);
+              } else if (ins->type==DIV_INS_FDS) {
+                NORMAL_MACRO(ins->std.ex2Macro,ins->std.ex2MacroLen,ins->std.ex2MacroLoop,ins->std.ex2MacroRel,0,ex2Max,"ex2","Mod Speed",160,ins->std.ex2MacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[5],0,ex2Max,NULL,false);
               } else {
                 NORMAL_MACRO(ins->std.ex2Macro,ins->std.ex2MacroLen,ins->std.ex2MacroLoop,ins->std.ex2MacroRel,0,ex2Max,"ex2","Envelope",ex2Bit?64:160,ins->std.ex2MacroOpen,ex2Bit,ayEnvBits,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[5],0,ex2Max,NULL,false);
               }
@@ -2327,6 +2358,9 @@ void FurnaceGUI::drawInsEdit() {
               NORMAL_MACRO(ins->std.fbMacro,ins->std.fbMacroLen,ins->std.fbMacroLoop,ins->std.fbMacroRel,0,252,"fb","Wave len. to Load",160,ins->std.fbMacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[8],0,252,NULL,false);
               NORMAL_MACRO(ins->std.fmsMacro,ins->std.fmsMacroLen,ins->std.fmsMacroLoop,ins->std.fmsMacroRel,0,2,"fms","Waveform load",64,ins->std.fmsMacroOpen,true,n163UpdateBits,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[9],0,2,NULL,false);
             }
+            if (ins->type==DIV_INS_FDS) {
+              NORMAL_MACRO(ins->std.ex3Macro,ins->std.ex3MacroLen,ins->std.ex3MacroLoop,ins->std.ex3MacroRel,0,127,"ex3","Mod Position",160,ins->std.ex3MacroOpen,false,NULL,false,NULL,0,0,0,NULL,uiColors[GUI_COLOR_MACRO_OTHER],mmlString[6],0,2,NULL,false);
+            }
 
             MACRO_END;
           } else { // classic view
diff --git a/src/gui/plot_nolerp.cpp b/src/gui/plot_nolerp.cpp
index 1c1cf94a..c8970c95 100644
--- a/src/gui/plot_nolerp.cpp
+++ b/src/gui/plot_nolerp.cpp
@@ -332,6 +332,8 @@ int PlotCustomEx(ImGuiPlotType plot_type, const char* label, float (*values_gett
             scale_max = v_max;
     }
 
+    if (blockMode) scale_max+=1.0f;
+
     ImU32 bgColor=ImGui::GetColorU32(ImVec4(color.x,color.y,color.z,color.w*0.15));
 
     ImGui::RenderFrame(frame_bb.Min, frame_bb.Max, ImGui::GetColorU32(ImGuiCol_FrameBg), true, style.FrameRounding);
@@ -372,7 +374,7 @@ int PlotCustomEx(ImGuiPlotType plot_type, const char* label, float (*values_gett
         float v0 = values_getter(data, (0) % values_count);
         float t0 = 0.0f;
         ImVec2 tp0 = ImVec2( t0, 1.0f - ImSaturate((v0 - scale_min) * inv_scale) );                       // Point in the normalized space of our target rectangle
-        float histogram_zero_line_t = (scale_min * scale_max < 0.0f) ? (1 + scale_min * inv_scale) : (scale_min < 0.0f ? 0.0f : 1.0f);   // Where does the zero line stands
+        float histogram_zero_line_t = (scale_min * scale_max < 0.0f) ? (1 + (blockMode?(scale_min-0.5):scale_min) * inv_scale) : (scale_min < 0.0f ? 0.0f : 1.0f);   // Where does the zero line stands
 
         const ImU32 col_base = ImGui::GetColorU32(color);
         const ImU32 col_hovered = ImGui::GetColorU32(color);