diff --git a/12_day/bootpack.c b/12_day/bootpack.c
index a2468c9..811e2ef 100644
--- a/12_day/bootpack.c
+++ b/12_day/bootpack.c
@@ -10,7 +10,7 @@ void HariMain(void)
 	struct BOOTINFO *binfo = (struct BOOTINFO *) ADR_BOOTINFO;
 	char s[40], keybuf[32], mousebuf[128];
 	int mx, my, i;
-	unsigned int memtotal, count = 0;
+	unsigned int memtotal;
 	struct MOUSE_DEC mdec;
 	struct MEMMAN *memman = (struct MEMMAN *) MEMMAN_ADDR;
 	struct SHTCTL *shtctl;
@@ -62,8 +62,7 @@ void HariMain(void)
 	sheet_refresh(sht_back, 0, 0, binfo->scrnx, 48); /* 刷新文字 */
 
 	for (;;) {
-		count++; /* 从这里开始 */
-		sprintf(s, "%010d", count);
+		sprintf(s, "%010d", timerctl.count);
 		boxfill8(buf_win, 160, COL8_C6C6C6, 40, 28, 119, 43);
 		putfonts8_asc(buf_win, 160, 40, 28, COL8_000000, s);
 		sheet_refresh(sht_win, 40, 28, 120, 44); /* 到这里结束 */
diff --git a/12_day/bootpack.h b/12_day/bootpack.h
index dd81c9b..4453c10 100644
--- a/12_day/bootpack.h
+++ b/12_day/bootpack.h
@@ -169,5 +169,10 @@ void sheet_slide(struct SHEET *sht, int vx0, int vy0);
 void sheet_free(struct SHEET *sht);
 
 /* timer.c */
+struct TIMERCTL {
+	unsigned int count;
+};
+extern struct TIMERCTL timerctl;
+
 void init_pit(void);
 void inthandler20(int *esp);
diff --git a/12_day/timer.c b/12_day/timer.c
index 1020139..41b7e81 100644
--- a/12_day/timer.c
+++ b/12_day/timer.c
@@ -5,16 +5,20 @@
 #define PIT_CTRL 0x0043
 #define PIT_CNT0 0x0040
 
+struct TIMERCTL timerctl;
+
 void init_pit(void)
 {
 	io_out8(PIT_CTRL, 0x43);
 	io_out8(PIT_CNT0, 0x9c);
 	io_out8(PIT_CNT0, 0x2e);
+	timerctl.count = 0;
+	return;
 }
 
 void inthandler20(int *esp)
 {
 	io_out8(PIC0_OCW2, 0x60); /* 把IRQ-00信号接收完了的信息通知给PIC */
-	/* 暂时什么也不做 */    
+	timerctl.count++;
 	return;
 }