diff --git a/.gitignore b/.gitignore
index 301b097..21f2c54 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,3 +17,6 @@
 /myapi.key
 /.suf
 tags
+.gdb_history
+peda*.txt
+.*.swp
diff --git a/CODING b/CODING
index 898097e..f1d0795 100644
--- a/CODING
+++ b/CODING
@@ -15,8 +15,6 @@ We have the following conventions in our code:
 
 * Function names are all lower-case separated by underscores.
 
-* Beginning-of-line indentation via tabs, not spaces.
-
 * Preprocessor macros are always UPPERCASE.
   There are a few grandfathered exceptions: assert, panic,
   static_assert, offsetof.
diff --git a/README.info b/README.info
new file mode 100644
index 0000000..eaf6de5
--- /dev/null
+++ b/README.info
@@ -0,0 +1,4 @@
+Lab 1 : Tue 10:00 ~ 11:20
+Lab 2 : Tue 12:00 ~ 13:20
+Lab 3 : Wed 15:00 ~ 16:20
+Lab 4 : Fri 14:00 ~ 15:20
diff --git a/kern/monitor.c b/kern/monitor.c
index 4e00796..7156224 100644
--- a/kern/monitor.c
+++ b/kern/monitor.c
@@ -22,6 +22,7 @@ struct Command {
 	int (*func)(int argc, char** argv, struct Trapframe* tf);
 };
 
+// LAB 1: add your command to here...
 static struct Command commands[] = {
 	{ "help", "Display this list of commands", mon_help },
 	{ "kerninfo", "Display information about the kernel", mon_kerninfo },
@@ -58,7 +59,9 @@ mon_kerninfo(int argc, char **argv, struct Trapframe *tf)
 int
 mon_backtrace(int argc, char **argv, struct Trapframe *tf)
 {
-	// Your code here.
+	// LAB 1: Your code here.
+    // HINT 1: use read_ebp().
+    // HINT 2: print the current ebp on the first line (not current_ebp[0])
 	return 0;
 }
 
diff --git a/kern/trap.c b/kern/trap.c
index 1ca8182..2dfaa17 100644
--- a/kern/trap.c
+++ b/kern/trap.c
@@ -66,14 +66,26 @@ static const char *trapname(int trapno)
 }
 
 
+// XYZ: write a function declaration here...
+// e.g., void t_divide();
+
 void
 trap_init(void)
 {
 	extern struct Segdesc gdt[];
 
+    /*
+     *
+     * HINT
+     * Do something like this: SETGATE(idt[T_DIVIDE], 0, GD_KT, t_divide, 0);
+     * if your trap handler's name for divide by zero is t_device.
+     * Additionally, you should declare trap handler as a function
+     * to refer that in C code... (see the comment XYZ above)
+     *
+     */
 	// LAB 3: Your code here.
 
-	// Per-CPU setup 
+	// Per-CPU setup
 	trap_init_percpu();
 }
 
diff --git a/kern/trapentry.S b/kern/trapentry.S
index 2dbeeca..7b51b6a 100644
--- a/kern/trapentry.S
+++ b/kern/trapentry.S
@@ -48,9 +48,15 @@
  * Lab 3: Your code here for generating entry points for the different traps.
  */
 
-
+// HINT 1 : TRAPHANDLER_NOEC(t_divide, T_DIVIDE);
+//          Do something like this if there is no error code for the trap
+// HINT 2 : TRAPHANDLER(t_dblflt, T_DBLFLT);
+//          Do something like this if the trap includes an error code..
+// HINT 3 : READ Intel's manual to check if the trap includes an error code
+//          or not...
 
 /*
  * Lab 3: Your code here for _alltraps
  */
 
+
diff --git a/lib/printfmt.c b/lib/printfmt.c
index 22e6abe..2aeb2dc 100644
--- a/lib/printfmt.c
+++ b/lib/printfmt.c
@@ -207,7 +207,7 @@ vprintfmt(void (*putch)(int, void*), void *putdat, const char *fmt, va_list ap)
 
 		// (unsigned) octal
 		case 'o':
-			// Replace this with your code.
+			// LAB 1: Replace this with your code.
 			putch('X', putdat);
 			putch('X', putdat);
 			putch('X', putdat);
diff --git a/student.info b/student.info
new file mode 100644
index 0000000..f3ede52
--- /dev/null
+++ b/student.info
@@ -0,0 +1,5 @@
+OSU  ID  (xxx-yyy-zzz)  : 933456789
+FLIP ID (e.g., jangye)  : jangye
+Name                    : Yeongjin Jang
+CS 444/544 ?            : 444
+Lab Class #             : Lab 1