diff --git a/Greeter.cpp b/Greeter.cpp
index 576fd54..415393d 100755
--- a/Greeter.cpp
+++ b/Greeter.cpp
@@ -97,7 +97,7 @@ int main(int argc, char **argv){
 		return 0;
 	}
 	train1->DoTask ();// a train of 10 times should be enough, so just do it once
-	train2->DoTask ();
+	train2->DoOrUndoTasks (1);
 	// show that the train is running on its own
 	printf ("Trains were started and should be printing in a second\n");
 	// a loop to show we can do real work in the main thread while the pulsedThreads do their own things.
diff --git a/pulsedThread.cpp b/pulsedThread.cpp
index a438a42..17f9a89 100755
--- a/pulsedThread.cpp
+++ b/pulsedThread.cpp
@@ -440,6 +440,7 @@ void pulsedThread::DoTasks(unsigned int nTasks){
 	pthread_mutex_unlock( &theTask.taskMutex );
 }
 
+
 /* ************ countermands currently requested tasks ***************************************
  The thread will finish the current pulse or train of pulses then stop
  Last Modified:
@@ -455,6 +456,31 @@ void pulsedThread::UnDoTasks (void){
     }
 }
 
+
+/* ****************************************************************************************************
+// gets the lock on the task and increments doTask to signal the thread to do task it is configured to do nTasks times
+//Last Modified:
+2018/11/05 by Jmie Boyd - added bounds checking
+2018/10/25 by Jamie Boyd - initial version */
+void pulsedThread::DoOrUndoTasks(int nTasks){
+	// for infinite task, this function is a NOP
+	if (theTask.nPulses != kINFINITETRAIN){
+		pthread_mutex_lock (&theTask.taskMutex);
+		// scrunch resulting value of doTask between 0 and kMODDELAY (first of signal bits)
+		unsigned int currentTasks = (theTask.doTask &~kMODANY);
+		if ((int)(currentTasks + nTasks) < 0){
+			theTask.doTask &= 1;
+		}else{
+			if ((int)currentTasks + nTasks >= kMODDELAY){
+				theTask.doTask = kMODDELAY -1;
+			}else{
+				theTask.doTask +=nTasks;
+			}
+		}
+		pthread_cond_signal(&theTask.taskVar);
+		pthread_mutex_unlock( &theTask.taskMutex );
+	}
+}
 /* ****************************************************************************************************
 /returns 0 if a thread is not currently doing a task, else returns number of tasks still left to do
 Last Modified 2015/09/28 by Jamie Boyd -  initial verison */
diff --git a/pulsedThread.h b/pulsedThread.h
index d362125..c62772c 100755
--- a/pulsedThread.h
+++ b/pulsedThread.h
@@ -242,6 +242,7 @@ class pulsedThread{
 		void DoTask (void); // requests that the thread perform its task once, as currently configured, if not an infinite train, or will start an infinite train
 		void DoTasks (unsigned int nTasks); // requests that the thread perform its task nTasks times, as currently configured, or
 		void UnDoTasks (void); // removes requested tasks in doTask, save 1. Thread stops after current task
+		void DoOrUndoTasks(int nTasks); // signed integer, to add OR ubtract from the number of tasks left to do
 		int isBusy(void); // checks if a task is busy, returns how many tasks are left to do
 		int waitOnBusy(float timeOut); // doesn't return until a thread is no longer busy
 		// for infinite trains