diff --git a/.gitignore b/.gitignore
index c6127b3..010ee81 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 # Prerequisites
+build
 *.d
 
 # Object files
diff --git a/boot/boot.c b/boot/boot.c
index 8dcd959..4a29add 100644
--- a/boot/boot.c
+++ b/boot/boot.c
@@ -2,7 +2,6 @@
 #include "dat.h"
 #include "fn.h"
 
-
 void (*probe1[])(void) = {
 	a20up,
 };
@@ -31,24 +30,10 @@ machdep(void)
 }
 
 static void
-puts(char *s)
-{
-	for(;*s; ++s)
-		putchar(*s);
-}
-
-static void
-putcn(char *s, int n)
-{
-	for(int i=0; i < n; ++i)
-		putchar(s[i]);
-}
-
-static int
 rdline(char *buf, int n)
 {
 	char *p = buf;
-	char *e = buf + n;
+	char *e = buf + n - 1;
 
 	while(p < e){
 		int c = getchar();
@@ -70,18 +55,20 @@ rdline(char *buf, int n)
 	}
 	putchar('\n');
 done:
-	return p - buf;
+	*p = 0;
 }
 
 void
 boot(int bootdev)
 {
 	machdep();	
+	print("\n\n===> Hello world <===\n\tBooted on disk 0x%x\n", bootdev);
+
 	for(;;){
 		char buf[8192];
 
-		puts("\nboot >> ");
-		int l = rdline(buf, sizeof(buf));
-		putcn(buf, l);
+		print("\nboot >> ");
+		rdline(buf, sizeof buf);
+		print("%s", buf);
 	}
 }
diff --git a/boot/fn.h b/boot/fn.h
index bc3c673..3d4c75c 100644
--- a/boot/fn.h
+++ b/boot/fn.h
@@ -6,6 +6,7 @@ void pcputc(int dev, int c);
 // print.c
 void putchar(int c);
 int getchar(void);
+void print(const char *fmt, ...);
 
 // a20.c
 void a20up(void);
diff --git a/boot/print.c b/boot/print.c
index 6d571b5..857ff56 100644
--- a/boot/print.c
+++ b/boot/print.c
@@ -2,13 +2,55 @@
 #include "dat.h"
 #include "fn.h"
 
-#define TABWIDTH 8
+#define TABWIDTH 4
 
 static void conputc(int c);
 static int congetc(void);
-
+static void doprint(void (*put)(int), const char *fmt, va_list ap);
+static void putint(void (*put)(int), int n, const char *sym, int base);
 static int pos = 0;
 
+void
+print(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);	
+	doprint(putchar, fmt, args);
+	va_end(args);
+}
+
+static void
+doprint(void (*put)(int), const char *s, va_list ap)
+{
+	while(*s){
+		if(*s != '%'){
+			put(*s++);
+			continue;
+		}
+		++s;
+		switch(*s){
+		case 'd':
+			putint(put, va_arg(ap,int), "0123456789", 10);		
+			break;
+		case 'x':
+			putint(put, va_arg(ap,int), "0123456789abcdef", 16);
+			break;
+		case 'X':
+			putint(put, va_arg(ap,int), "0123456789ABCDEF", 16);
+			break;
+		case 's':
+			for(char *p=va_arg(ap,char*); *p; ++p)
+				put(*p);
+			break;
+		default:
+			return;
+		}	
+		++s;
+	}
+}
+
+
 int
 getchar(void)
 {
@@ -67,3 +109,19 @@ congetc(void)
 {
 	return condev.getc(condev.dev);
 }
+
+static void
+putint(void (*put)(int), int n, const char *sym, int base)
+{
+	int i;
+	char buf[16];
+
+	i = 0;
+	do{
+		buf[i++] = n%base;
+		n /= base;
+	}while(n);
+	do{
+		put((int)sym[(int)buf[--i]]);
+	}while(i);
+}
\ No newline at end of file
diff --git a/u.h b/u.h
index 6be17ee..920a125 100644
--- a/u.h
+++ b/u.h
@@ -1,5 +1,6 @@
 #define elem(x) ((int)(sizeof(x)/sizeof((x)[0])))
 #define nil		((void*)0)
+#define USED(x) if(x);
 
 typedef	unsigned short	ushort;
 typedef	unsigned char	uchar;
@@ -18,4 +19,16 @@ typedef unsigned long long u64;
 typedef signed char i8;
 typedef signed short i16;
 typedef signed int i32;
-typedef signed long long i64;
\ No newline at end of file
+typedef signed long long i64;
+
+typedef char* va_list;
+#define va_start(list, start) ((list) = (char*)((int*)&(start)+1))
+#define va_end(list)				\
+	USED(list)
+
+#define va_arg(list, mode)			\
+	((sizeof(mode) == 1) ? 			\
+		((list += 4), (mode*)list)[-4]:	\
+	(sizeof(mode) == 2) ?			\
+		((list += 4), (mode*)list)[-2]:	\
+		((list += sizeof(mode)), (mode*)list)[-1])