diff --git a/csim.c b/csim.c
index 54814b9..64dea3b 100644
--- a/csim.c
+++ b/csim.c
@@ -22,23 +22,28 @@ Exit statuses:
 /* Typedefs and structs */
 typedef unsigned char uint8_t;
 
-/* UNSURE. As defined in conference. */
-struct line_s {
+/* Linked Line and related prototypes */
+typedef struct linked_line_s linked_line;
+struct linked_line_s {
 	uint8_t validity;
-	int tag;
+	long tag;
+	linked_line* newer;
+	linked_line* older;
 };
-typedef struct line_s line;
+
 
 /* Macros */
 #define mprintf(...) if (VERBOSE) printf(__VA_ARGS__)
 
-/* Prototypes */
+/* General Prototypes */
 void print_usage(void);
 void bad_usage_error(void);
 long parse_int_arg(char *arg, char opt);
 long bits_to_size(int bits);
-line** make_cache(long set_indices, long lines);
-void free_cache(line** cache, long lines);
+linked_line** make_cache(long set_indices, long num_lines);
+linked_line* make_set(linked_line* newer, long num_lines);
+void free_cache(linked_line** cache, long num_sets);
+void free_set(linked_line* line);
 
 /* Global variables */
 uint8_t VERBOSE = 0; /**< If nonzero, mprintf will not print. Set in main() if -v flag is given. */
@@ -86,7 +91,7 @@ int main(int argc, char* argv[])
 	/* End of argument parsing. */
 	//probably broken: printf("Arguments: s=%hhu, E=%u, b=%hhu, t=%s, v=%hhu, 2^s=%d, 2^b=%u\n", set_index_bits, num_lines, block_bits, filename, VERBOSE, set_indices, block_size);
 
-	line** cache = make_cache(set_indices, num_lines);
+	linked_line** cache = make_cache(set_indices, num_lines);
 
 	/* FILE READING */
 	FILE* f = fopen(filename, "r");
@@ -114,31 +119,63 @@ int main(int argc, char* argv[])
 	printSummary(0, 0, 0);
 
 	fclose(f);
-	free_cache(cache, num_lines);
+	free_cache(cache, set_index_bits);
 
 	return 0;
 }
 
-/** What do you think? */
-line** make_cache(long set_indices, long lines)
+
+
+
+linked_line** make_cache(long set_indices, long num_lines)
 {
-	line** cache = calloc(set_indices, sizeof(line*));
-	int ii;
-	for (ii = 0; ii < lines; ii++) {
-		cache[ii] = calloc(lines, sizeof(line));
+	linked_line** cache = (linked_line**)calloc(set_indices, sizeof(linked_line*));
+	long ii;
+	for (ii = 0; ii < num_lines; ii++) {
+		cache[ii] = make_set(NULL, num_lines);
 	}
 	return cache;
 }
 
-void free_cache(line** cache, long lines)
+/**
+   Creates a set by creating and linking a given number of lines.
+   @param newer A pointer to the previously-created element of the set.
+   @param num_lines The number of lines remaining to be added.
+   @return A pointer to the created line.
+*/
+linked_line* make_set(linked_line* newer, long num_lines) {
+	linked_line* current = (linked_line*)calloc(1, sizeof(linked_line));
+	current->newer = newer;
+	if (num_lines) { // If not on the last line
+		current->older = make_set(current, num_lines-1);
+	}
+	else {
+		current->older = NULL;
+	}
+	return current;
+}
+
+void free_cache(linked_line** cache, long num_sets)
 {
 	int ii;
-	for (ii = 0; ii < lines; ii++) {
-		free(cache[ii]);
+	for (ii = 0; ii < num_sets; ii++) {
+		free_set(cache[ii]);
 	}
 	free(cache);
 }
 
+/**
+   Frees a set by recursing through it, then freeing each element from oldest to newest.
+   @param line A pointer to the next line in the set.
+   @param num_lines The number
+ */
+void free_set(linked_line* line) {
+	if (line != NULL) {
+		free_set(line->older);
+		free(line);
+	}
+}
+
 void print_usage(void)
 {
 	printf("Usage: ./csim [-hv] -s <number> -E <number> -b <number> -t <file>\n"