diff --git a/README.md b/README.md
index 3343e30..56663bb 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,15 @@
 as -o model.o model.S
 ld -o model model.o
 ```
+
+#### R0 Status Codes (Linux)
+
+```
+ 1	: standard out (monitor)
+```
+
+#### R7 Linux Service Commands
+
+```
+ 4	: write string
+```
diff --git a/math/modulus/mod.S b/math/modulus/mod.S
new file mode 100644
index 0000000..91dce6a
--- /dev/null
+++ b/math/modulus/mod.S
@@ -0,0 +1,13 @@
+/*****************************************************************************
+*
+* Name:
+*
+* Description:
+*
+* Author: Curtis L. Lewis
+* Date:
+*
+******************************************************************************/
+/*
+-------|-------|----------------|----------------------------------------------
+*/
diff --git a/utils/v_dec/README.md b/utils/v_dec/README.md
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/utils/v_dec/README.md
diff --git a/utils/v_dec/v_dec_orig.S b/utils/v_dec/v_dec_orig.S
new file mode 100644
index 0000000..11aadcd
--- /dev/null
+++ b/utils/v_dec/v_dec_orig.S
@@ -0,0 +1,56 @@
+/*****************************************************************************
+*
+* Name: v_dec_orig
+*
+* Description: display numbers in decimal
+*
+* From Chapter 7 of "Assembly Language Using the Raspberry Pi" by Robert Dunne
+* Pages: 151 - 168
+*
+* Author: 
+* Date:
+*
+*------|-------|----------------|----------------------------------------------
+*
+******************************************************************************/
+
+	.global _start
+
+_start:	mov	r0, #125	 // An arbitrary sample decimal value for test
+	bl	v_dec		 // Call subroutine to view dec value in R0 in
+				 // ASCI
+	mov	r0, #0		 // Exit status code
+	mov 	r7, #1		 // service command to terminate program
+	svc	0		 // Issue Linux command to terminate program
+
+/*
+  Subroutine v_dec will display a 32-bit register in decimal digits
+
+  	r0	: contains number to be displayed
+		  if negative (bit 31 = 1), then a minus sign will be output
+	lr	: contains return address
+
+	ALL REGISTER CONTENTS WILL BE PRESERVED
+*/
+
+v_dec:	push 	{r0 - r7}	 // Save contents of registers r0 through r7
+	mov	r3, r0		 // r3 will hold a copy of input word to be
+				 // displayed
+	mov	r2, #1		 // number of characters to display at a time
+	mov     r0, #1		 // code for standard output
+	mov     r7, #4		 // Linux service command to write string
+
+// If bit 31 is set, then register contains a negative number and "-" should
+// be output.
+
+	cmp	r3, #0		 // determin if minus sign is needed
+	bge	absval		 // if positive number, then display it
+	ldr	r1, =msign	 // address of minus sign in memory
+	svc	0		 // service call to write string out to stdout
+
+	rsb	r3, r3, #0	 // get absolute value (negative of negative)
+				 // for display
+
+/*
+-------|-------|----------------|----------------------------------------------
+*/