diff --git a/15_day/bootpack.c b/15_day/bootpack.c
index 42ea912..224c5de 100644
--- a/15_day/bootpack.c
+++ b/15_day/bootpack.c
@@ -22,7 +22,7 @@ void HariMain(void)
 	struct FIFO32 fifo;
 	char s[40];
 	int fifobuf[128];
-	struct TIMER *timer, *timer2, *timer3;
+	struct TIMER *timer, *timer2, *timer3, *timer_ts;
 	int mx, my, i, cursor_x, cursor_c, task_b_esp;
 	unsigned int memtotal;
 	struct MOUSE_DEC mdec;
@@ -60,6 +60,9 @@ void HariMain(void)
 	timer3 = timer_alloc();
 	timer_init(timer3, &fifo, 1);
 	timer_settime(timer3, 50);
+	timer_ts = timer_alloc();
+	timer_init(timer_ts, &fifo, 2);
+	timer_settime(timer_ts, 2);
 
 	memtotal = memtest(0x00400000, 0xbfffffff);
 	memman_init(memman);
@@ -128,7 +131,10 @@ void HariMain(void)
 		} else {
 			i = fifo32_get(&fifo);
 			io_sti();
-			if (256 <= i && i <= 511) { /* 键盘数据*/
+			if (i == 2) {
+				farjmp(0, 4 * 8);
+				timer_settime(timer_ts, 2);
+			} else if (256 <= i && i <= 511) { /* 键盘数据*/
 				sprintf(s, "%02X", i - 256);
 				putfonts8_asc_sht(sht_back, 0, 16, COL8_FFFFFF, COL8_008484, s, 2);
 				if (i < 0x54 + 256) {
@@ -185,7 +191,6 @@ void HariMain(void)
 				}
 			} else if (i == 10) { /* 10秒定时器 */
 				putfonts8_asc_sht(sht_back, 0, 64, COL8_FFFFFF, COL8_008484, "10[sec]", 7);
-				taskswitch4();
 			} else if (i == 3) { /* 3秒定时器 */
 				putfonts8_asc_sht(sht_back, 0, 80, COL8_FFFFFF, COL8_008484, "3[sec]", 6);
 			} else if (i <= 1) { /* 光标用定时器*/
@@ -279,12 +284,12 @@ void make_textbox8(struct SHEET *sht, int x0, int y0, int sx, int sy, int c)
 void task_b_main(void)
 {
 	struct FIFO32 fifo;
-	struct TIMER *timer;
+	struct TIMER *timer_ts;
 	int i, fifobuf[128];
 	fifo32_init(&fifo, 128, fifobuf);
-	timer = timer_alloc();
-	timer_init(timer, &fifo, 1);
-	timer_settime(timer, 500);
+	timer_ts = timer_alloc();
+	timer_init(timer_ts, &fifo, 1);
+	timer_settime(timer_ts, 2);
 
 	for (;;) {
 		io_cli();
@@ -293,8 +298,9 @@ void task_b_main(void)
 		} else {
 			i = fifo32_get(&fifo);
 			io_sti();
-			if (i == 1) { /*超时时间为5秒 */
-				taskswitch3(); /*返回任务A */
+			if (i == 1) { /*任务切换*/
+				farjmp(0, 3 * 8);
+				timer_settime(timer_ts, 2);
 			}
 		}
 	}
diff --git a/15_day/bootpack.h b/15_day/bootpack.h
index 5868890..14fe41c 100644
--- a/15_day/bootpack.h
+++ b/15_day/bootpack.h
@@ -28,8 +28,7 @@ void asm_inthandler21(void);
 void asm_inthandler27(void);
 void asm_inthandler2c(void);
 unsigned int memtest_sub(unsigned int start, unsigned int end);
-void taskswitch3(void);
-void taskswitch4(void);
+void farjmp(int eip, int cs);
 
 /* fifo.c */
 struct FIFO32 {
diff --git a/15_day/naskfunc.nas b/15_day/naskfunc.nas
index d7194a7..6901d26 100644
--- a/15_day/naskfunc.nas
+++ b/15_day/naskfunc.nas
@@ -16,7 +16,7 @@
 		GLOBAL	_asm_inthandler20, _asm_inthandler21
 		GLOBAL	_asm_inthandler27, _asm_inthandler2c
 		GLOBAL	_memtest_sub
-		GLOBAL	_taskswitch3, _taskswitch4
+		GLOBAL	_farjmp
 		EXTERN	_inthandler20, _inthandler21
 		EXTERN	_inthandler27, _inthandler2c
 
@@ -207,10 +207,6 @@ mts_fin:
 		POP		EDI
 		RET
 
-_taskswitch3:  ; void taskswitch3(void);
-		JMP    3*8:0
-		RET
-
-_taskswitch4:	; void taskswitch4(void);
-		JMP		4*8:0
-		RET
+_farjmp:		; void farjmp(int eip, int cs);
+		JMP    FAR [ESP+4]    ; eip, cs
+		RET
\ No newline at end of file