diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index bee45e4b3..6a23663ab 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -2973,6 +2973,9 @@ bool DivEngine::init() {
   oscBuf[0]=new float[32768];
   oscBuf[1]=new float[32768];
 
+  memset(oscBuf[0],0,32768*sizeof(float));
+  memset(oscBuf[1],0,32768*sizeof(float));
+
   initDispatch();
   renderSamples();
   reset();
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 40f00e91e..50729a155 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -3927,6 +3927,9 @@ bool FurnaceGUI::init() {
   if (orderEditMode<0) orderEditMode=0;
   if (orderEditMode>3) orderEditMode=3;
 
+  oscZoom=e->getConfFloat("oscZoom",0.5f);
+  oscWindowSize=e->getConfFloat("oscWindowSize",20.0f);
+
   pianoOctaves=e->getConfInt("pianoOctaves",pianoOctaves);
   pianoOctavesEdit=e->getConfInt("pianoOctavesEdit",pianoOctavesEdit);
   pianoOptions=e->getConfBool("pianoOptions",pianoOptions);
@@ -4137,6 +4140,10 @@ bool FurnaceGUI::finish() {
   e->setConf("followPattern",followPattern);
   e->setConf("orderEditMode",orderEditMode);
 
+  // commit oscilloscope state
+  e->setConf("oscZoom",oscZoom);
+  e->setConf("oscWindowSize",oscWindowSize);
+
   // commit piano state
   e->setConf("pianoOctaves",pianoOctaves);
   e->setConf("pianoOctavesEdit",pianoOctavesEdit);
@@ -4422,6 +4429,7 @@ FurnaceGUI::FurnaceGUI():
   openSampleFilterOpt(false),
   oscTotal(0),
   oscZoom(0.5f),
+  oscWindowSize(20.0f),
   oscZoomSlider(false),
   chanOscCols(3),
   chanOscWindowSize(20.0f),
diff --git a/src/gui/gui.h b/src/gui/gui.h
index 2c6d54b00..e62311c12 100644
--- a/src/gui/gui.h
+++ b/src/gui/gui.h
@@ -1240,6 +1240,7 @@ class FurnaceGUI {
   int oscTotal;
   float oscValues[512];
   float oscZoom;
+  float oscWindowSize;
   bool oscZoomSlider;
 
   // per-channel oscilloscope
diff --git a/src/gui/osc.cpp b/src/gui/osc.cpp
index f85a323d6..406d3ccce 100644
--- a/src/gui/osc.cpp
+++ b/src/gui/osc.cpp
@@ -21,9 +21,6 @@
 #include "imgui_internal.h"
 #include <imgui.h>
 
-// TODO:
-// - potentially move oscilloscope seek position to the end, and read the last samples
-//   - this allows for setting up the window size
 void FurnaceGUI::readOsc() {
   int writePos=e->oscWritePos;
   int readPos=e->oscReadPos;
@@ -47,8 +44,11 @@ void FurnaceGUI::readOsc() {
   total=oscTotal+(bias>>6);
   if (total>avail) total=avail;
   //printf("total: %d. avail: %d bias: %d\n",total,avail,bias);
+
+  int winSize=e->getAudioDescGot().rate*(oscWindowSize/1000.0);
+  int oscReadPos=(writePos-winSize)&0x7fff;
   for (int i=0; i<512; i++) {
-    int pos=(readPos+(i*total/512))&0x7fff;
+    int pos=(oscReadPos+(i*winSize/512))&0x7fff;
     oscValues[i]=(e->oscBuf[0][pos]+e->oscBuf[1][pos])*0.5f;
     if (oscValues[i]>0.001f || oscValues[i]<-0.001f) {
       WAKE_UP;
@@ -97,6 +97,14 @@ void FurnaceGUI::drawOsc() {
         if (oscZoom>2.0) oscZoom=2.0;
       }
       ImGui::SameLine();
+      if (ImGui::VSliderFloat("##OscWinSize",ImVec2(20.0f*dpiScale,ImGui::GetContentRegionAvail().y),&oscWindowSize,5.0,100.0)) {
+        if (oscWindowSize<5.0) oscWindowSize=5.0;
+        if (oscWindowSize>100.0) oscWindowSize=100.0;
+      }
+      if (ImGui::IsItemClicked(ImGuiMouseButton_Middle)) {
+        oscWindowSize=20.0;
+      }
+      ImGui::SameLine();
     }
 
     ImDrawList* dl=ImGui::GetWindowDrawList();