diff --git a/arith/Makefile b/arith/Makefile
index c650405..4a6bfdc 100644
--- a/arith/Makefile
+++ b/arith/Makefile
@@ -1,4 +1,4 @@
-TARGETS = adder substractor multiplier divider negator comparator
+TARGETS = adder substractor multiplier divider negator comparator shifter
 
 .PHONY: all clean
 
@@ -18,4 +18,6 @@ divider:
 negator:
 	gcc -I../common/ ../common/auxiliar.c negator.c -o negator
 comparator:
-	gcc -I../common/ ../common/auxiliar.c comparator.c -o comparator
\ No newline at end of file
+	gcc -I../common/ ../common/auxiliar.c comparator.c -o comparator
+shifter:
+	gcc -I../common/ ../common/auxiliar.c shifter.c -o shifter
\ No newline at end of file
diff --git a/arith/adder.c b/arith/adder.c
index c890fa1..8fa1587 100644
--- a/arith/adder.c
+++ b/arith/adder.c
@@ -14,8 +14,6 @@ int check_length(char **inputs, uint8_t num_inputs)
 
 int main(int argc, char **argv)
 {
-	int i;
-	int pos;
 	if(argc != 2)
 	{
 		error();
@@ -41,9 +39,9 @@ int main(int argc, char **argv)
 		error();
 	}
 	int a,b,carry_in,c;
-	a = bin2dec(inputs[0]);
-	b = bin2dec(inputs[1]);
-	carry_in = bin2dec(inputs[2]);
+	a = bin2udec(inputs[0]);
+	b = bin2udec(inputs[1]);
+	carry_in = bin2udec(inputs[2]);
 	c = a+b+carry_in;
 	char *result = dec2bin(c,input_length+1);
 	printf("%s,%c",result+1,result[0]);
diff --git a/arith/bit_adder.c b/arith/bit_adder.c
new file mode 100644
index 0000000..9d7a80b
--- /dev/null
+++ b/arith/bit_adder.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <string.h>
+#include "auxiliar.h"
+
+int main(int argc, char **argv)
+{
+	if(argc != 2)
+	{
+		error();
+	}
+	char *input = argv[1];
+	if(!strcmp(input,"error"))
+	{
+		error();
+	}
+	char **inputs = comma_separate(input);
+	if(inputs == NULL)
+	{
+		error();
+	}
+	int num_inputs = num_occurrences(input,',');
+	if(num_inputs != 1)
+	{
+		error();
+	}
+	int input_length = strlen(inputs[0]);
+	int num = bin2dec(inputs[0]);
+	num *= -1;
+	char *result = dec2bin(num,input_length);
+	printf("%s",result);
+	free(result);
+	free_mem(inputs,num_inputs);
+	return 0;
+}
diff --git a/arith/bit_finder.c b/arith/bit_finder.c
new file mode 100644
index 0000000..9d7a80b
--- /dev/null
+++ b/arith/bit_finder.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <string.h>
+#include "auxiliar.h"
+
+int main(int argc, char **argv)
+{
+	if(argc != 2)
+	{
+		error();
+	}
+	char *input = argv[1];
+	if(!strcmp(input,"error"))
+	{
+		error();
+	}
+	char **inputs = comma_separate(input);
+	if(inputs == NULL)
+	{
+		error();
+	}
+	int num_inputs = num_occurrences(input,',');
+	if(num_inputs != 1)
+	{
+		error();
+	}
+	int input_length = strlen(inputs[0]);
+	int num = bin2dec(inputs[0]);
+	num *= -1;
+	char *result = dec2bin(num,input_length);
+	printf("%s",result);
+	free(result);
+	free_mem(inputs,num_inputs);
+	return 0;
+}
diff --git a/arith/comparator.c b/arith/comparator.c
index 4b6108f..90c90b8 100644
--- a/arith/comparator.c
+++ b/arith/comparator.c
@@ -2,6 +2,9 @@
 #include <string.h>
 #include "auxiliar.h"
 
+#define SIGNED 	 1
+#define UNSIGNED 0
+
 int check_length(char **inputs, uint8_t num_inputs)
 {
 	int input_length = strlen(inputs[0]);
@@ -14,9 +17,8 @@ int check_length(char **inputs, uint8_t num_inputs)
 
 int main(int argc, char **argv)
 {
-	int i;
-	int pos;
-	if(argc != 2)
+	uint8_t signedness;
+	if(argc != 3)
 	{
 		error();
 	}
@@ -25,6 +27,18 @@ int main(int argc, char **argv)
 	{
 		error();
 	}
+	if(!strcmp("unsigned", argv[2]))
+	{
+		signedness = UNSIGNED;
+	}
+	else if(!strcmp("signed", argv[2]))
+	{
+		signedness = SIGNED;
+	}
+	else
+	{
+		error();
+	}
 	char **inputs = comma_separate(input);
 	if(inputs == NULL)
 	{
@@ -37,8 +51,16 @@ int main(int argc, char **argv)
 	}
 	int input_length = check_length(inputs,num_inputs);
 	int a,b;
-	a = bin2dec(inputs[0]);
-	b = bin2dec(inputs[1]);
+	if(signedness == UNSIGNED)
+	{
+		a = bin2udec(inputs[0]);
+		b = bin2udec(inputs[1]);
+	}
+	else if(signedness == SIGNED)
+	{
+		a = bin2dec(inputs[0]);
+		b = bin2dec(inputs[1]);
+	}
 	if(a > b)
 	{
 		printf("1,0,0");
diff --git a/arith/divider.c b/arith/divider.c
index 163d93f..51dde77 100644
--- a/arith/divider.c
+++ b/arith/divider.c
@@ -18,8 +18,6 @@ int check_length(char **inputs, uint8_t num_inputs)
 
 int main(int argc, char **argv)
 {
-	int i;
-	int pos;
 	if(argc != 2)
 	{
 		error();
@@ -51,8 +49,8 @@ int main(int argc, char **argv)
 	memset(op,0x00,input_length+1);
 	strcpy(op,upper);
 	strcat(op,lower);
-	a = bin2dec(op);
-	b = bin2dec(inputs[2]);
+	a = bin2udec(op);
+	b = bin2udec(inputs[2]);
 	c = a/b;
 	rem = a%b;
 	char *result = dec2bin(c,input_length);
diff --git a/arith/multiplier.c b/arith/multiplier.c
index 487d40f..e723a19 100644
--- a/arith/multiplier.c
+++ b/arith/multiplier.c
@@ -18,8 +18,6 @@ int check_length(char **inputs, uint8_t num_inputs)
 
 int main(int argc, char **argv)
 {
-	int i;
-	int pos;
 	if(argc != 2)
 	{
 		error();
@@ -45,9 +43,9 @@ int main(int argc, char **argv)
 		error();
 	}
 	int a,b,carry_in,c;
-	a = bin2dec(inputs[0]);
-	b = bin2dec(inputs[1]);
-	carry_in = bin2dec(inputs[2]);
+	a = bin2udec(inputs[0]);
+	b = bin2udec(inputs[1]);
+	carry_in = bin2udec(inputs[2]);
 	c = (a*b)+carry_in;
 	char *result = dec2bin(c,input_length*2);
 	printf("%s,%.*s",result+input_length,input_length,result);
diff --git a/arith/negator.c b/arith/negator.c
index 2166863..9d7a80b 100644
--- a/arith/negator.c
+++ b/arith/negator.c
@@ -4,8 +4,6 @@
 
 int main(int argc, char **argv)
 {
-	int i;
-	int pos;
 	if(argc != 2)
 	{
 		error();
diff --git a/arith/shifter.c b/arith/shifter.c
new file mode 100644
index 0000000..d776617
--- /dev/null
+++ b/arith/shifter.c
@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <string.h>
+#include "auxiliar.h"
+
+#define LEFT  	0
+#define RIGHT 	1
+#define LOGIC 	0
+#define ARITH 	1
+#define ROTATE 	2
+
+int main(int argc, char **argv)
+{
+	uint8_t direction, type;
+	int shift;
+	if(argc != 3)
+	{
+		error();
+	}
+	char *input = argv[1];
+	if(!strcmp(input,"error"))
+	{
+		error();
+	}
+	char **inputs = comma_separate(input);
+	if(inputs == NULL)
+	{
+		error();
+	}
+	int num_inputs = num_occurrences(input,',');
+	if(num_inputs != 2)
+	{
+		error();
+	}
+	int input_length = strlen(inputs[0]);
+	if(!strcmp("logic-left",argv[2]))
+	{
+		type = LOGIC;
+		direction = LEFT;
+	}
+	else if(!strcmp("logic-right",argv[2]))
+	{
+		type = LOGIC;
+		direction = RIGHT;
+	}
+	else if(!strcmp("arith-left",argv[2]))
+	{
+		type = ARITH;
+		direction = LEFT;
+	}
+	else if(!strcmp("arith-right",argv[2]))
+	{
+		type = ARITH;
+		direction = RIGHT;
+	}
+	else if(!strcmp("rotate-left",argv[2]))
+	{
+		type = ROTATE;
+		direction = LEFT;
+	}
+	else if(!strcmp("rotate-right",argv[2]))
+	{
+		type = ROTATE;
+		direction = RIGHT;
+	}
+	else
+	{
+		error();
+	}
+	shift = bin2udec(inputs[1]);
+	while(shift >= input_length)
+	{
+		shift = shift % input_length;
+	}
+	char *result;
+	if(!shift)
+	{
+		result = inputs[0];
+	}
+	else
+	{
+		if(type == LOGIC)
+		{
+			if(direction == LEFT)
+			{
+				result = dec2bin(bin2udec(inputs[0]) << shift,input_length);
+			}
+			else
+			{
+				result = dec2bin(bin2udec(inputs[0]) >> shift,input_length);
+			}
+		}
+		else if(type == ARITH)
+		{
+			if(direction == LEFT)
+			{
+				result = dec2bin(bin2dec(inputs[0]) << shift,input_length);
+			}
+			else
+			{
+				result = dec2bin(bin2dec(inputs[0]) >> shift,input_length);
+			}
+		}
+		else if(type == ROTATE)
+		{
+			if(direction == RIGHT)
+			{
+				shift = input_length - shift;
+			}
+			result = (char*) malloc(sizeof(char) * (input_length+1));
+			memset(result,0x00,input_length);
+			strncpy(result,inputs[0]+shift,input_length-shift);
+			strncpy(result + (input_length-shift),inputs[0],shift);
+		}
+	}
+	printf("%s",result);
+	free(result);
+	free_mem(inputs,num_inputs);
+	return 0;
+}
diff --git a/arith/substractor.c b/arith/substractor.c
index a89f120..d505406 100644
--- a/arith/substractor.c
+++ b/arith/substractor.c
@@ -14,8 +14,6 @@ int check_length(char **inputs, uint8_t num_inputs)
 
 int main(int argc, char **argv)
 {
-	int i;
-	int pos;
 	if(argc != 2)
 	{
 		error();
@@ -42,9 +40,9 @@ int main(int argc, char **argv)
 	}
 	int a,b,borrow_in,c;
 	char borrow_out = '0';
-	a = bin2dec(inputs[0]);
-	b = bin2dec(inputs[1]);
-	borrow_in = bin2dec(inputs[2]);
+	a = bin2udec(inputs[0]);
+	b = bin2udec(inputs[1]);
+	borrow_in = bin2udec(inputs[2]);
 	c = a-(b+borrow_in);
 	if(c < 0)
 	{
diff --git a/common/auxiliar.c b/common/auxiliar.c
index c2faea2..bda1aef 100644
--- a/common/auxiliar.c
+++ b/common/auxiliar.c
@@ -150,6 +150,27 @@ int bin2dec(char *bin)
         return num;
 }
 
+int bin2udec(char *bin)
+{
+        int i;
+        int num = 0;
+        int length = strlen(bin);
+        int pos = length - 1;
+        char *aux = (char*) malloc(sizeof(char) * (length+1));
+        memset(aux,0x00,length+1);
+        strcpy(aux,bin);
+        normalize(&aux,1);
+        for(i = 0; i < length; i++)
+        {
+                if(aux[pos--])
+                {
+                        num += 0x1 << i;
+                }
+        }
+        free(aux);
+        return num;
+}
+
 char* dec2bin(int dec, int length)
 {
         char *bin = (char*) malloc(sizeof(char) * (length + 1));
diff --git a/common/auxiliar.h b/common/auxiliar.h
index e5dc34e..c787556 100644
--- a/common/auxiliar.h
+++ b/common/auxiliar.h
@@ -15,6 +15,7 @@ void free_mem(char **inputs, int num_inputs);
 
 void normalize(char **inputs, int num_inputs);
 int bin2dec(char *bin);
+int bin2udec(char *bin);
 char* dec2bin(int dec, int length);
 void expand_input(char **input, int required_length);
 void reverse_two_complement(char *bin);