diff --git a/CVReader.ino b/CVReader.ino
index 49431c9..ccea2d3 100644
--- a/CVReader.ino
+++ b/CVReader.ino
@@ -24,13 +24,13 @@ void setup() {
   Serial.begin(115200);
   DCC::begin();
 
-  DIAG(F("\n===== CVReader begin ==============================\n"));
-
-  for (byte x = 0; x < sizeof(cvnums) / sizeof(cvnums[0]); x++) {
-    int value = DCC::readCV(cvnums[x]);
-    DIAG(F("\nCV %d = %d  0x%x  %s\n"), cvnums[x], value, value, value >= 0 ? " VERIFIED OK" : "FAILED VERIFICATION");
-  }
-  DIAG(F("\n===== CVReader done ==============================\n"));
+//  DIAG(F("\n===== CVReader begin ==============================\n"));
+//
+//  for (byte x = 0; x < sizeof(cvnums) / sizeof(cvnums[0]); x++) {
+//    int value = DCC::readCV(cvnums[x]);
+//    DIAG(F("\nCV %d = %d  0x%x  %s\n"), cvnums[x], value, value, value >= 0 ? " VERIFIED OK" : "FAILED VERIFICATION");
+//  }
+//  DIAG(F("\n===== CVReader done ==============================\n"));
   DIAG(F("\nReady for JMRI commands\n"));
 }
 
diff --git a/DCC.cpp b/DCC.cpp
index 439faab..79e42a3 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -27,21 +27,20 @@ void DCC::setThrottle( uint16_t cab, uint8_t tSpeed, bool tDirection)  {
 
 void DCC::setThrottle2( uint16_t cab, uint8_t tSpeed, bool tDirection)  {
  
-  uint8_t b[5];
+  uint8_t b[4];
   uint8_t nB = 0;
 
   if (cab > 127)
     b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
-
   b[nB++] = lowByte(cab);
-  b[nB++] = 0x3F;                      // 128-step speed control byte
+  b[nB++] = SET_SPEED;                      // 128-step speed control byte
   b[nB++] = tSpeed + (tSpeed > 0) + tDirection * 128; // max speed is 126, but speed codes range from 2-127 (0=stop, 1=emergency stop)
  
   DCCWaveform::mainTrack.schedulePacket(b, nB, 0);
 }
 
 void DCC::setFunction(int cab, byte byte1)  {
-  uint8_t b[4];
+  uint8_t b[3];
   uint8_t nB = 0;
 
   if (cab > 127)
@@ -53,7 +52,7 @@ void DCC::setFunction(int cab, byte byte1)  {
 }
 
 void DCC::setFunction(int cab, byte byte1, byte byte2)  {
-  byte b[5];
+  byte b[4];
   byte nB = 0;
 
   if (cab > 127)
@@ -66,7 +65,7 @@ void DCC::setFunction(int cab, byte byte1, byte byte2)  {
 }
 
 void DCC::setAccessory(int address, byte number, bool activate) {
-  byte b[3];                      // save space for checksum byte
+  byte b[2];                    
 
   b[0] = address % 64 + 128;                                     // first byte is of the form 10AAAAAA, where AAAAAA represent 6 least signifcant bits of accessory address
   b[1] = ((((address / 64) % 8) << 4) + (number % 4 << 1) + activate % 2) ^ 0xF8; // second byte is of the form 1AAACDDD, where C should be 1, and the least significant D represent activate/deactivate
@@ -75,13 +74,13 @@ void DCC::setAccessory(int address, byte number, bool activate) {
 }
 
 void DCC::writeCVByteMain(int cab, int cv, byte bValue)  {
-  byte b[6];                      // save space for checksum byte
+  byte b[5];                     
   byte nB = 0;
   if (cab > 127)
     b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
 
   b[nB++] = lowByte(cab);
-  b[nB++] = cv1(0xEC, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
+  b[nB++] = cv1(WRITE_BYTE_MAIN, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
   b[nB++] = cv2(cv);
   b[nB++] = bValue;
 
@@ -89,7 +88,7 @@ void DCC::writeCVByteMain(int cab, int cv, byte bValue)  {
 }
 
 void DCC::writeCVBitMain(int cab, int cv, byte bNum, bool bValue)  {
-  byte b[6];                      // save space for checksum byte
+  byte b[5];                      
   byte nB = 0;
   bValue = bValue % 2;
   bNum = bNum % 8;
@@ -98,52 +97,51 @@ void DCC::writeCVBitMain(int cab, int cv, byte bNum, bool bValue)  {
     b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
 
   b[nB++] = lowByte(cab);
-  b[nB++] = cv1(0xE8, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
+  b[nB++] = cv1(WRITE_BIT_MAIN, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
   b[nB++] = cv2(cv);
-  b[nB++] = 0xF0 + bValue * 8 + bNum;
+  b[nB++] = WRITE_BIT | (bValue?BIT_ON:BIT_OFF) | bNum;
 
   DCCWaveform::mainTrack.schedulePacket(b, nB, 4);
 }
 
 bool  DCC::writeCVByte(int cv, byte bValue)  {
-  uint8_t message[] = {cv1(0x7C, cv), cv2(cv), bValue};
+  uint8_t message[] = {cv1(WRITE_BYTE, cv), cv2(cv), bValue};
   DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 6);           // NMRA recommends 6 write or reset packets for decoder recovery time
-  return verifyCV(cv, bValue);
+  return verifyCVByte(cv, bValue);
 }
 
+bool DCC::verifyCVByte(int cv, byte value) {
+  byte message[] = { cv1(VERIFY_BYTE, cv), cv2(cv), value};
+  return DCCWaveform::progTrack.schedulePacketWithAck(message, sizeof(message), 5);
+  }
 
 bool DCC::writeCVBit(int cv, byte bNum, bool bValue)  {
-  bValue = bValue % 2;
-  bNum = bNum % 8;
-  uint8_t message[] = {cv1(0x78, cv), cv2(cv), 0xF0 + bValue * 8 + bNum};
-  DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 6);           // NMRA recommends 6 write or reset packets for decoder recovery time
-
-  /* TODO... what is the verify opcode here?
-    bitWrite(message[2],4,1);              // change instruction code from Write Bit to Verify Bit
-    DCCWaveform::progTrack.schedulePacket(message,sizeof(message),6);             // NMRA recommends 6 write or reset packets for decoder recovery time
-  */
- return true; // <<<< NOT  ACCURATE... see comment above 
+  if (bNum>=8) return false;
+  byte instruction=WRITE_BIT | bValue?BIT_ON:BIT_OFF | bNum;
+  byte message[] = {cv1(BIT_MANIPULATE, cv), cv2(cv), instruction };
+  DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 6);           // NMRA recommends 6 write or reset packets for decoder recovery time 
+  return verifyCVBit(cv, bNum, bValue); 
 }
 
+bool DCC::verifyCVBit(int cv, byte bNum, bool bValue)  {
+  if (bNum>=8) return false;
+  byte instruction=VERIFY_BIT | bValue?BIT_ON:BIT_OFF | bNum;
+  byte message[] = {cv1(BIT_MANIPULATE, cv), cv2(cv), instruction };
+  return DCCWaveform::progTrack.schedulePacketWithAck(message, sizeof(message), 5);           // NMRA recommends 6 write or reset packets for decoder recovery time
+}
+
+
 
 int DCC::readCV(int cv)  {
-  byte message[] = {  cv1(0x78, cv)  , // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
-                      cv2(cv),
-                      0
-                   };    // trailing zero will be updated in loop below
-
   byte value = 0;
-
-  // get each bit individually
-  for (int i = 0; i < 8; i++) {
-    message[2] = 0xE8 + i;
-    bool one=DCCWaveform::progTrack.schedulePacketWithAck(message, sizeof(message), 4);     // NMRA recommends 5 read packets
-    value += one << i;
+  // get each bit individually by validating against a one. 
+  for (int bNum = 0; bNum < 8; bNum++) {
+    value += verifyCVBit(cv,bNum,true) << bNum;
   }
-
-  return verifyCV(cv, value) ? value : -1;
+  return verifyCVByte(cv, value) ? value : -1;
 }
 
+  
 void DCC::loop()  {
   DCCWaveform::loop(); // powwer overload checks
   // if the main track transmitter still has a pending packet, skip this loop.
@@ -167,6 +165,7 @@ void DCC::loop()  {
 }
 
 ///// Private helper functions below here /////////////////////
+
 byte DCC::cv1(byte opcode, int cv)  {
   cv--;
   return (highByte(cv) & (byte)0x03) | opcode;
@@ -176,11 +175,7 @@ byte DCC::cv2(int cv)  {
   return lowByte(cv);
 }
 
-bool DCC::verifyCV(int cv, byte value) {
-  byte message[] = { cv1(0x74, cv), cv2(cv), value};
-  DIAG(F("\n\nVerifying cv %d = %d"), cv, value);
-  return DCCWaveform::progTrack.schedulePacketWithAck(message, sizeof(message), 5);
-  }
+
 
 void  DCC::updateLocoReminder(int loco, byte tSpeed, bool forward) {
   // determine speed reg for this loco
diff --git a/DCC.h b/DCC.h
index 8022454..041e576 100644
--- a/DCC.h
+++ b/DCC.h
@@ -14,7 +14,9 @@ class DCC {
   static void setThrottle( uint16_t cab, uint8_t tSpeed, bool tDirection);
   static int  readCV(int cv);
   static bool writeCVByte(int cv, byte bValue) ;
+  static bool verifyCVByte(int cv,byte bValue);
   static bool writeCVBit(int cv, byte bNum, bool bValue);
+  static bool verifyCVBit(int cv, byte bNum, bool bValue);
   static void writeCVByteMain(int cab, int cv, byte bValue);
   static void writeCVBitMain(int cab, int cv, byte bNum, bool bValue);
   static void setFunction( int cab, byte fByte, byte eByte);
@@ -28,13 +30,23 @@ private:
        byte speed;
        bool forward;
   };
-  static bool verifyCV(int cv,byte bValue);
   static void setThrottle2( uint16_t cab, uint8_t tSpeed, bool tDirection);
   static void updateLocoReminder(int loco, byte tSpeed, bool forward);
   static int nextLoco;
   static LOCO speedTable[MAX_LOCOS];
   static byte cv1(byte opcode, int cv);
   static byte cv2(int cv);
-  
+
+  // NMRA codes #
+  static const byte SET_SPEED=0x3f;
+  static const byte WRITE_BYTE_MAIN = 0xEC;
+  static const byte WRITE_BIT_MAIN = 0xE8;
+  static const byte WRITE_BYTE = 0x7C;
+  static const byte VERIFY_BYTE= 0x74;
+  static const byte BIT_MANIPULATE=0x78;
+  static const byte WRITE_BIT=0xF0;
+  static const byte VERIFY_BIT=0xE0;
+  static const byte BIT_ON=0x08;
+  static const byte BIT_OFF=0x00;
 };
 #endif