diff --git a/src/main/java/org/redstonechips/basiccircuits/BasicCircuits.java b/src/main/java/org/redstonechips/basiccircuits/BasicCircuits.java
index a6c210c..eb699d4 100755
--- a/src/main/java/org/redstonechips/basiccircuits/BasicCircuits.java
+++ b/src/main/java/org/redstonechips/basiccircuits/BasicCircuits.java
@@ -11,8 +11,8 @@
 public class BasicCircuits extends CircuitLibrary {
     @Override
     public Class[] getCircuitClasses() {
-        return new Class[] { adder.class, and.class, clock.class, counter.class, demultiplexer.class, divider.class, flipflop.class,
-                multiplexer.class, multiplier.class, or.class, pisoregister.class, print.class, random.class, receiver.class,
+        return new Class[] { adder.class, and.class, clock.class, counter.class, combocounter.class, demultiplexer.class, divider.class,
+                flipflop.class, multiplexer.class, multiplier.class, or.class, pisoregister.class, print.class, random.class, receiver.class,
                 shiftregister.class, transmitter.class, xor.class, decoder.class, encoder.class, pixel.class, pulse.class, not.class,
                 synth.class, srnor.class, terminal.class, router.class, ringcounter.class, iptransmitter.class, ipreceiver.class,
                 comparator.class, delay.class, repeater.class, nand.class, nor.class, xnor.class, segdriver.class, dregister.class, 
diff --git a/src/main/java/org/redstonechips/basiccircuits/combocounter.java b/src/main/java/org/redstonechips/basiccircuits/combocounter.java
new file mode 100644
index 0000000..3018a4d
--- /dev/null
+++ b/src/main/java/org/redstonechips/basiccircuits/combocounter.java
@@ -0,0 +1,92 @@
+package org.redstonechips.basiccircuits;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.redstonechips.circuit.Circuit;
+
+/**
+ * Combination counter that can both increment and decrement
+ */
+public class combocounter extends Circuit {
+    private int incPin = 0;
+    private int decPin = 1;
+    private int resetPin = 2;
+
+    int min;
+    int max;
+    int count;
+
+    @Override
+    public void input(boolean state, int inIdx) {
+        if (state) {
+            if (inIdx == incPin) {
+                if (count >= max) {
+                    count = min;
+                }
+                else {
+                    count = count + 1;
+                }
+                
+                if (chip.hasListeners()) debug("Counting " + count + ".");
+                this.writeInt(count, 0, outputlen);
+            }
+            else if (inIdx == decPin) {
+                if (count <= min) {
+                    count = max;
+                }
+                else {
+                    count = count - 1;
+                }
+                
+                if (chip.hasListeners()) debug("Counting " + count + ".");
+                this.writeInt(count, 0, outputlen);
+            }
+            else if (inIdx == resetPin) {
+                count = 0;
+                
+                if (chip.hasListeners()) debug("Resetting counter to " + count + ".");
+                this.writeInt(count, 0, outputlen);
+            }
+            
+        }
+    }
+
+    @Override
+    public Circuit init(String[] args) {
+        if (inputlen == 0) {
+            return error("Expecting at least 1 input.");
+        }
+
+        if (args.length==0) {
+            min = 0;
+            max = (int)Math.pow(2, outputlen) - 1;
+        }
+        else {
+            return error("Illegal number of arguments (max 0).");
+        }
+        
+        count = min;
+        return this;
+    }
+
+    @Override
+    public boolean isStateless() {
+        return false;
+    }
+
+    @Override
+    public void setInternalState(Map<String, String> state) {
+        String loadedCount = state.get("count");
+        if (loadedCount != null) {
+            count = Integer.decode(loadedCount);
+            writeInt(count, 0, outputlen);
+        }
+    }
+
+    @Override
+    public Map<String, String> getInternalState() {
+        Map<String,String> state = new HashMap<String, String>();
+        state.put("count", Integer.toString(count));
+        return state;
+    }
+}
diff --git a/src/main/java/org/redstonechips/basiccircuits/display.java b/src/main/java/org/redstonechips/basiccircuits/display.java
index 488dec3..2dd1e79 100755
--- a/src/main/java/org/redstonechips/basiccircuits/display.java
+++ b/src/main/java/org/redstonechips/basiccircuits/display.java
@@ -14,6 +14,7 @@
 import org.redstonechips.memory.RamListener;
 import org.redstonechips.util.BooleanArrays;
 import org.redstonechips.util.BooleanSubset;
+import org.redstonechips.util.Optional;
 import org.redstonechips.wireless.Receiver;
 
 /**
@@ -101,7 +102,8 @@ public void dataChanged(Ram ram, long address, boolean[] data) {
     private void refreshDisplayFromRam() {
         long offset = ramPage * ramPageLength;
         for (long i=offset; i<offset+ramPageLength; i++) {
-            int color = (int)BooleanArrays.toUnsignedInt(ram.read(i));
+            boolean[] data = ram.readDefaultZero(i, colorWordlength);
+            int color = (int)BooleanArrays.toUnsignedInt(data);
             int x = (int)((i-offset) % screen.getDescription().addrWidth);
             int y = (int)((i-offset) / screen.getDescription().addrWidth);
             
diff --git a/src/main/java/org/redstonechips/basiccircuits/dregister.java b/src/main/java/org/redstonechips/basiccircuits/dregister.java
index 6665219..ebcceb3 100755
--- a/src/main/java/org/redstonechips/basiccircuits/dregister.java
+++ b/src/main/java/org/redstonechips/basiccircuits/dregister.java
@@ -71,7 +71,7 @@ public Circuit init(String[] args) {
         if (ram != null) {
             ramListener = new dregisterRamListener();
             ram.addListener(ramListener);
-            this.writeBits(ram.read(ramaddr));
+            this.writeBits(ram.read(ramaddr).get());
             info("Created "+outputlen+"-bit register backed by memory: "+ram.getId()+"@"+Long.toHexString(ramaddr));
         } else
             info("Created "+outputlen+"-bit register.");
diff --git a/src/main/java/org/redstonechips/basiccircuits/encoder.java b/src/main/java/org/redstonechips/basiccircuits/encoder.java
index 9aacde7..ea26104 100755
--- a/src/main/java/org/redstonechips/basiccircuits/encoder.java
+++ b/src/main/java/org/redstonechips/basiccircuits/encoder.java
@@ -10,9 +10,20 @@ public class encoder extends Circuit {
 
     @Override
     public void input(boolean state, int inIdx) {
-        if (state) {
-            writeInt(inIdx, 0, outputlen);
-        } else {
+        int totalEnabledBits = 0;
+        int mostSignificantBit = -1;
+        
+        for (int i = 0; i < inputs.length; i++) {
+            if (inputs[i]) {
+                totalEnabledBits++;
+                mostSignificantBit = i;
+            }
+        }
+        
+        if (totalEnabledBits == 1) {
+            writeInt(mostSignificantBit, 0, outputlen);
+        }
+        else {
             this.clearOutputs();
         }
     }
diff --git a/src/main/java/org/redstonechips/basiccircuits/pixel.java b/src/main/java/org/redstonechips/basiccircuits/pixel.java
index f33c278..5238b63 100755
--- a/src/main/java/org/redstonechips/basiccircuits/pixel.java
+++ b/src/main/java/org/redstonechips/basiccircuits/pixel.java
@@ -181,7 +181,11 @@ public void receive(BooleanSubset bits) {
             // if we have 0 or 1 inputs there's no clock to adjust. just use the incoming bits.        
             boolean[] valbits;
             if (inputlen<=1) {
-                valbits = bits.copy(0, (inputlen==0?5:inputlen));
+                int copylen = 5;
+                if (bits.length() < copylen) {
+                    copylen = bits.length();
+                }
+                valbits = bits.copy(0, copylen);
             }  else {
                 valbits = new boolean[bits.length()+1];
                 for (int i=0; i<bits.length(); i++)
diff --git a/src/main/java/org/redstonechips/basiccircuits/pulse.java b/src/main/java/org/redstonechips/basiccircuits/pulse.java
index 14faf86..68ec843 100755
--- a/src/main/java/org/redstonechips/basiccircuits/pulse.java
+++ b/src/main/java/org/redstonechips/basiccircuits/pulse.java
@@ -10,23 +10,22 @@
 public class pulse extends Circuit {
 
     public enum EdgeTriggering { positive, negative, doubleEdge };
+    public enum RepeatedTriggerMode { legacy, ignore, extend };
 
     private EdgeTriggering trigger = EdgeTriggering.positive;
+    private RepeatedTriggerMode repeatedTriggerMode = RepeatedTriggerMode.legacy;
 
     private long interval;
     private PulseOff[] pulseOffs;
+    private Integer[] pulseOffIds;
     private long intervalInTicks;
 
     @Override
     public void input(boolean state, final int inIdx) {
         if (state && (trigger==EdgeTriggering.positive || trigger==EdgeTriggering.doubleEdge)) {
-            if (inputlen==outputlen)
-                pulse(inIdx);
-            else pulseSequence();
+            trigger(inIdx);
         } else if (!state && (trigger == EdgeTriggering.negative || trigger == EdgeTriggering.doubleEdge)) {
-            if (inputlen==outputlen)
-                pulse(inIdx);
-            else pulseSequence();
+            trigger(inIdx);
         }
 
     }
@@ -38,7 +37,6 @@ public Circuit init(String[] args) {
 
         if (inputlen==0) 
             return error("Expecting at least one input and one output.");
-        
 
         if (args.length==0) interval = 1000; // 1 sec default
         
@@ -51,33 +49,75 @@ public Circuit init(String[] args) {
         }
 
         if (args.length>=2) {
-            if (args.length==2) {
-                try {
-                    trigger = EdgeTriggering.valueOf(args[1]);
-                } catch (IllegalArgumentException ie) {
-                    return error("Bad trigger argument: " + args[1]);
-                }
+            try {
+                trigger = EdgeTriggering.valueOf(args[1]);
+            } catch (IllegalArgumentException ie) {
+                return error("Bad trigger argument: " + args[1]);
+            }
+        }
+        
+        if (args.length>=3) {
+            try {
+                repeatedTriggerMode = RepeatedTriggerMode.valueOf(args[2]);
+            } catch (IllegalArgumentException e) {
+                return error("Bad repeated trigger mode argument: " + args[2]);
             }
         }
+        
+        if (repeatedTriggerMode==RepeatedTriggerMode.extend && inputlen!=outputlen) {
+            return error("Extend mode is incompatible with sequence mode");
+        }
 
         if (interval!=0) {
             intervalInTicks = Math.round(interval/50);
+            pulseOffIds = new Integer[outputlen];
 
             pulseOffs = new PulseOff[outputlen];
             for (int i=0; i < outputlen; i++) {
-                pulseOffs[i] = new PulseOff(i);
+                pulseOffs[i] = new PulseOff(i, pulseOffIds);
             }
         }
 
         return this;
     }
-
+    
+    private void trigger(final int idx) {
+        int checkRepeatIdx = 0;
+        
+        if (repeatedTriggerMode==RepeatedTriggerMode.legacy) {
+            pulse(idx);
+        }
+        else {
+            if (inputlen==outputlen) {
+                checkRepeatIdx = idx;
+            }
+            if (repeatedTriggerMode==RepeatedTriggerMode.ignore) {
+                if (pulseOffIds[checkRepeatIdx]==null) {
+                    pulse(idx);
+                }
+            }
+            else if (repeatedTriggerMode==RepeatedTriggerMode.extend) {
+                if (pulseOffIds[checkRepeatIdx]!=null) {
+                    rc.getServer().getScheduler().cancelTask(pulseOffIds[checkRepeatIdx]);
+                    pulseOffIds[checkRepeatIdx] = null;
+                }
+                pulse(idx);
+            }
+        }
+    }
+    
     private void pulse(final int idx) {
+        if (inputlen==outputlen)
+            pulseSingle(idx);
+        else pulseSequence();
+    }
+
+    private void pulseSingle(final int idx) {
         write(true, idx);
         if (interval==0) {
             write(false, idx);
         } else {
-            rc.getServer().getScheduler().scheduleSyncDelayedTask(rc, pulseOffs[idx], intervalInTicks);
+            pulseOffIds[idx] = rc.getServer().getScheduler().scheduleSyncDelayedTask(rc, pulseOffs[idx], intervalInTicks);
         }
 
     }
@@ -90,18 +130,25 @@ private void pulseSequence() {
             }
         } else {
             write(true, 0);
-            rc.getServer().getScheduler().scheduleSyncDelayedTask(rc, pulseOffs[0], intervalInTicks);
+            pulseOffIds[0] = rc.getServer().getScheduler().scheduleSyncDelayedTask(rc, pulseOffs[0], intervalInTicks);
         }
     }
 
     class PulseOff implements Runnable {
         int index;
+        Integer[] pulseOffIds;
 
-        public PulseOff(int index) { this.index = index; }
+        public PulseOff(int index, Integer[] pulseOffIds) {
+            this.index = index;
+            this.pulseOffIds = pulseOffIds;
+        }
 
         @Override
         public void run() {
             write(false, index);
+            if (inputlen==outputlen || index==0) {
+                pulseOffIds[index] = null;
+            }
             if (inputlen!=outputlen && pulseOffs.length>index+1) {
                 write(true, index+1);
                 rc.getServer().getScheduler().scheduleSyncDelayedTask(rc, pulseOffs[index+1], intervalInTicks);
diff --git a/src/main/java/org/redstonechips/basiccircuits/sram.java b/src/main/java/org/redstonechips/basiccircuits/sram.java
index 44ce54e..6c520da 100755
--- a/src/main/java/org/redstonechips/basiccircuits/sram.java
+++ b/src/main/java/org/redstonechips/basiccircuits/sram.java
@@ -2,6 +2,7 @@
 package org.redstonechips.basiccircuits;
 
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.logging.Level;
 import org.redstonechips.paging.LineSource;
 import org.redstonechips.parsing.Range;
@@ -16,6 +17,7 @@
 import org.redstonechips.memory.RamListener;
 import org.redstonechips.paging.Pager;
 import org.redstonechips.util.BooleanArrays;
+import org.redstonechips.util.Optional;
 
 /**
  *
@@ -155,7 +157,8 @@ public void save() {
 
     private void readMemory() {
         long address = getInputAddress();
-        boolean[] data = memory.read(address);
+        boolean[] data = memory.readDefaultZero(address, wordLength);
+
         if (chip.hasListeners()) debug("Reading " + BooleanArrays.toPrettyString(data, wordLength) + " from address " + address);
         writeBits(data, 0, wordLength);
     }
@@ -301,9 +304,16 @@ public MemoryLineSource(int offset, int length) {
         public String getLine(int idx) {
             String value;
             String address = zeroPad(idx+offset, (int)Math.pow(2, addressLength)-1);
-            boolean[] data = memory.read(idx+offset);
-            if (wordLength>32) value = Long.toHexString(BooleanArrays.toSignedInt(data, 0, wordLength));
-            else value = BooleanArrays.toPrettyString(data, wordLength);
+            Optional<boolean[]> dataOpt = memory.read(idx+offset);
+            boolean[] data = memory.readDefaultZero(idx+offset, wordLength);
+            
+            if (wordLength > 32) {
+                value = Long.toHexString(BooleanArrays.toSignedInt(data, 0, wordLength));
+            }
+            else {
+                value = BooleanArrays.toPrettyString(data, wordLength);
+            }
+            
             return ChatColor.YELLOW.toString() + address + ": " + ChatColor.WHITE + value + "\n";
         }