diff --git a/testcases/run-in-simulavr.sh b/testcases/run-in-simulavr.sh
index a3429d9..8b0ba68 100755
--- a/testcases/run-in-simulavr.sh
+++ b/testcases/run-in-simulavr.sh
@@ -25,6 +25,7 @@ for GCODE_FILE in "triangle.gcode" "straight-speeds.gcode"; do
 
   FILE="${GCODE_FILE%.gcode}"
   VCD_FILE="${FILE}.vcd"
+  VEL_FILE="${FILE}.processed.vcd"
   
 
   # We assume here queue and rx buffer are large enough to read
@@ -84,7 +85,7 @@ for GCODE_FILE in "triangle.gcode" "straight-speeds.gcode"; do
   ' < "${VCD_FILE}"
 
 
-  # Finally, create a plot.
+  # Create a plot.
   gnuplot << EOF
     set terminal png size 1024,768
     set output "${FILE}.png"
@@ -101,7 +102,118 @@ for GCODE_FILE in "triangle.gcode" "straight-speeds.gcode"; do
          "${FILE}.data" using (\$2):(\$5) with dots title "Y feedrate"
 EOF
 
-  display "${FILE}.png" &
+
+  # Next task: rewrite the VCD file to add speed values.
+  #
+  # This is a bit tricky, as VCD files demand timestamps in ascending order.
+  # Strategy taken: write out all timestamped data with one line per event,
+  # then run it through 'sort -g' and reformat it yet again to be a properly
+  # formatted VCD file.
+  awk '
+    function print_binary(n, e) {  # n = number; e = number of bits
+      string = "";
+      for (i = 0; i < e; i++) {
+        if (n >= (2 ^ (e - 1))) # top bit set
+          string = string "1";
+        else
+          string = string "0";
+        n *= 2;
+        if (n > (2 ^ e))
+          n -= (2 ^ e);
+      }
+      return string;
+    }
+    BEGIN {
+      # These lines must match the ones after the sort.
+      intLen = 16;
+      xStepID = "0"; xVelID = "1";
+      yStepID = "2"; yVelID = "3";
+
+      xDir = yDir = 0;
+      xPos = yPos = 0;
+      xVel = yVel = 0;
+      yAcc = yAcc = 0;
+      lastxTime = lastyTime = 0;
+    }
+    /^#/ {
+      time = substr($0, 2);
+      if (time == 0) {
+        do {
+          getline;
+        } while ($0 != "$end");
+      }
+      next;
+    }
+    {
+      bit = substr($1, 2);
+      if ($2 == "0") { # X Dir
+        if (bit == 0) xDir = -1;
+        else if (bit == 1) xDir = 1;
+        else xDir = 0;
+      }
+      if ($2 == "2") { # Y Dir
+        if (bit == 0) yDir = -1;
+        else if (bit == 1) yDir = 1;
+        else yDir = 0;
+      }
+      if ($2 == "1") { # X Step
+        if (bit == 1) { # raising flange
+          xPos += xDir;
+          xVel = 1000000000 / (time - lastxTime);
+          print lastxTime " b" print_binary(xVel, intLen) " " xVelID;
+          print time " b" bit " " xStepID;
+          lastxTime = time;
+        } else { # falling flange
+          print time " b" bit " " xStepID;
+        }
+      }
+      if ($2 == "3") { # Y Step
+        if (bit == 1) { # raising flange
+          yPos += yDir;
+          yVel = 1000000000 / (time - lastyTime);
+          print lastyTime " b" print_binary(yVel, intLen) " " yVelID;
+          print time " b" bit " " yStepID;
+          lastyTime = time;
+        } else { # falling flange
+          print time " b" bit " " yStepID;
+        }
+      }
+    }
+  ' < "${VCD_FILE}" | \
+  sort -g | \
+  awk '
+    BEGIN {
+      # These lines must match the ones before the sort.
+      intLen = 16;
+      xStepID = "0"; xVelID = "1";
+      yStepID = "2"; yVelID = "3";
+      lastTime = "";
+
+      print "$timescale 1ns $end";
+      print "$scope module Steppers $end";
+      print "$var wire 1 " xStepID " X_step $end";
+      print "$var integer " intLen " " xVelID " X_steps/s $end";
+      print "$var wire 1 " yStepID " Y_step $end";
+      print "$var integer " intLen " " yVelID " Y_steps/s $end";
+      print "$upscope $end";
+      print "$enddefinitions $end";
+      print "#0";
+      print "$dumpvars";
+      print "b0 " xStepID;
+      print "b0 " xVelID;
+      print "b0 " yStepID;
+      print "b0 " yVelID;
+      print "$end";
+    }
+    {
+      if ($1 != lastTime) {
+        print "#" $1;
+        lastTime = $1;
+      }
+      print $2 " " $3;
+    }
+  ' > "${VEL_FILE}"
+
 
 done