diff --git a/.blocksize.go.swp b/.blocksize.go.swp
new file mode 100644
index 0000000..d406db0
Binary files /dev/null and b/.blocksize.go.swp differ
diff --git a/blocksize b/blocksize
index f51619b..20bc95f 100755
Binary files a/blocksize and b/blocksize differ
diff --git a/blocksize.go b/blocksize.go
index 7179560..a9f2402 100644
--- a/blocksize.go
+++ b/blocksize.go
@@ -33,13 +33,13 @@ func main() {
 
 	if dasd == "" { // no dasd type was input
 		fmt.Println("\nBLK205R No DASD type entered. ")
-		fmt.Println("\nBLK206R pls enter DASD type or restart with -h for list of DASD types")
+		fmt.Println("BLK206R pls enter DASD type or restart with -h for list of DASD types")
 		fmt.Scan(&dasd)
 	}
 	if lrecl == 0 { // no lrecl was input
 
 		fmt.Printf("\nBLK201R lrecl command line argument is not included.\n")
-		fmt.Println("\nBLK202R Please enter lrecl length: ")
+		fmt.Println("BLK202R Please enter lrecl length: ")
 		fmt.Scan(&lrecl)
 	}
 	if *helpPtr { // user asked for help
diff --git a/concurrency b/concurrency
new file mode 100755
index 0000000..eabb86a
Binary files /dev/null and b/concurrency differ
diff --git a/concurrency.go b/concurrency.go
new file mode 100644
index 0000000..e07315e
--- /dev/null
+++ b/concurrency.go
@@ -0,0 +1,72 @@
+package main
+
+/* 2017 copyright by moshix
+   with Apache license             */
+import (
+	"flag"
+	"fmt"
+	"time"
+)
+
+func ta(tamsec int) {
+	for i := 0; i < 9999999; i++ {
+		fmt.Println("Thread A: counter: ", i)
+		time.Sleep(time.Duration(tamsec) * time.Millisecond)
+	}
+}
+func tb(tbmsec int) {
+
+	for i := 0; i < 9999999; i++ {
+		fmt.Println("Thread B counter: ", i)
+		time.Sleep(time.Duration(tbmsec) * time.Millisecond)
+	}
+}
+func timeoutfunc(t chan bool, toutsec int) {
+	time.Sleep(time.Duration(toutsec) * time.Second)
+	t <- true
+}
+
+func main() {
+
+	var tamsec int = 300
+	var tbmsec int = 100
+	var toutsec int = 15
+
+	threadaPtr := flag.Int("tamsec", 300, "thread A millisecond wait time")
+	threadbPtr := flag.Int("tbmsec", 100, "thread B millisecond wait time")
+	toutPtr := flag.Int("tout", 15, "timeout period")
+	helpPtr := flag.Bool("help", false, "help flag")
+	flag.Parse()
+
+	if *helpPtr { //user asked for help...
+		fmt.Println("\nconcurrency is a Golang concurrency testing tool by moshix")
+		fmt.Println("Two parameters are needed, and a flag is optional:")
+		fmt.Println("-tamsec=nnn  hundreds of milliseconds for thread A to wait")
+		fmt.Println("-tbmsec=nnn hundreds of milliseconds for thread B to wait")
+		fmt.Println("-tout=nn  tens of seconds for time-out of all threads.")
+		fmt.Println("-help for this help dialog")
+		fmt.Println("\nconcurrency will in any case time out after 15 seconds")
+		fmt.Println("you can determine the relative and absolute veleocity of each thread by assigning sensible values in tamsec and tbmsec. Have fun!")
+
+		return
+	}
+
+	tamsec = *threadaPtr //assign argument of thread A wait time in msec
+	tbmsec = *threadbPtr //assign argument of thread B wait time in msec
+	toutsec = *toutPtr   // assign time out in seconds
+	t := make(chan bool)
+	go timeoutfunc(t, toutsec)
+
+	go ta(tamsec)
+	go tb(tbmsec)
+
+	for {
+
+		tend := <-t
+		if tend == true {
+			fmt.Println("time-out from control and timing thread!")
+			return
+		}
+
+	}
+}