diff --git a/IO_DNOU8.h b/IO_DNOU8.h
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+++ b/IO_DNOU8.h
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+/*
+ *  © 2022, Chris Harlow. All rights reserved.
+ *  
+ *  This file is part of DCC++EX API
+ *
+ *  This is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#ifndef IO_DNOU8_h
+ #define IO_DNOU8_h
+#include <Arduino.h>
+#include "IODevice.h"
+#define GET_BIT(bit) ((_pinValues[bit/8] >>(bit%8) == 1))
+#define SET_BIT(bit) _pinValues[bit/8] |= 1<<(bit%8)
+#define CLR_BIT(bit) _pinValues[bit/8] &= ~(1<<(bit%8))
+
+class IO_DNOU8 : public IODevice {
+public:
+  static void create(VPIN firstVpin, int nPins, byte latchPin, byte clockPin, byte dataPin ) 
+  {
+      new IO_DNOU8( firstVpin,  nPins,  latchPin,  clockPin,  dataPin);
+  }  
+
+protected:
+  IO_DNOU8(VPIN firstVpin, int nPins, byte latchPin, byte clockPin, byte dataPin) :
+    IODevice(firstVpin, nPins) {
+    _latchPin=latchPin;
+    _clockPin=clockPin;
+    _dataPin=dataPin;
+    _nShiftBytes=(nPins+7)/8; // rounded up to multiples of 8 bits
+    _pinValues=(byte*) calloc(_nShiftBytes,1);  
+    // Connect to HAL so my _write, _read and _loop will be called as required.
+    IODevice::addDevice(this);  
+  }
+
+// Called by HAL to start handling this device
+  void _begin() override {
+    _xmitPending=true; // will cause transmission of all zeros first time out
+    _deviceState = DEVSTATE_NORMAL;
+    pinMode(_latchPin,OUTPUT);
+    pinMode(_clockPin,OUTPUT);
+    pinMode(_dataPin,OUTPUT);
+    _display();
+  }
+
+void _loop(unsigned long currentMicros) override {
+   (void)currentMicros;  // Not needed
+
+   if (!_xmitPending) return; // Nothing to do
+
+    #ifdef DIAG_IO
+        // We will create a DIAG on the fly
+        USB_SERIAL.print("<* DNOU8 ");
+    #endif
+
+    // stream out the bitmap (highest pin first)
+    _xmitPending=false; 
+    digitalWrite(_latchPin, LOW);
+    
+    for (int xmitBit=_nShiftBytes*8 -1; xmitBit>=0; xmitBit--) {
+        bool bit=GET_BIT(xmitBit);
+    #ifdef DIAG_IO
+        USB_SERIAL.print(bit?'1':'0');
+    #endif
+        digitalWrite(_dataPin,bit);
+        digitalWrite(_clockPin,HIGH);
+        digitalWrite(_clockPin,LOW);
+    }
+    
+    digitalWrite(_latchPin, HIGH);
+    #ifdef DIAG_IO
+        USB_SERIAL.print(" *>\n");
+    #endif           
+  }
+
+  void _write(VPIN vpin, int value) override {
+    int pin = vpin - _firstVpin;
+    bool oldval=GET_BIT(pin);
+    bool newval=value!=0;
+    if (newval==oldval) return; // no change  
+    if (newval) SET_BIT(pin);
+           else CLR_BIT(pin);
+    _xmitPending=true;  // shift register will be sent on next _loop()
+  }
+
+  int _read(VPIN vpin) override {
+    int pin = vpin - _firstVpin;
+    return GET_BIT(pin);
+  }
+
+  void _display() override {
+      DIAG(F("IO_DNOU8 Configured on VPins:%d-%d"), (int)_firstVpin, 
+    (int)_firstVpin+_nPins-1);
+  }
+
+private:
+  bool _xmitPending=false;
+  int  _nShiftBytes=0; 
+  VPIN _latchPin,_clockPin,_dataPin;
+  byte* _pinValues;
+};
+
+#endif
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