diff --git a/16_day/bootpack.c b/16_day/bootpack.c
index 85eb835..22dc57f 100644
--- a/16_day/bootpack.c
+++ b/16_day/bootpack.c
@@ -7,13 +7,6 @@ void make_window8(unsigned char *buf, int xsize, int ysize, char *title);
 void putfonts8_asc_sht(struct SHEET *sht, int x, int y, int c, int b, char *s, int l);
 void make_textbox8(struct SHEET *sht, int x0, int y0, int sx, int sy, int c);
 
-struct TSS32 {
-	int backlink, esp0, ss0, esp1, ss1, esp2, ss2, cr3;
-	int eip, eflags, eax, ecx, edx, ebx, esp, ebp, esi, edi;
-	int es, cs, ss, ds, fs, gs;
-	int ldtr, iomap;
-};
-
 void task_b_main(struct SHEET *sht_back);
 
 void HariMain(void)
@@ -23,7 +16,7 @@ void HariMain(void)
 	char s[40];
 	int fifobuf[128];
 	struct TIMER *timer, *timer2, *timer3;
-	int mx, my, i, cursor_x, cursor_c, task_b_esp;
+	int mx, my, i, cursor_x, cursor_c;
 	unsigned int memtotal;
 	struct MOUSE_DEC mdec;
 	struct MEMMAN *memman = (struct MEMMAN *) MEMMAN_ADDR;
@@ -38,8 +31,7 @@ void HariMain(void)
 		0, 0, 0, 0, 0, 0, 0, '7', '8', '9', '-', '4', '5', '6', '+', '1',
 		'2', '3', '0', '.'
 	};
-	struct TSS32 tss_a, tss_b;
-	struct SEGMENT_DESCRIPTOR *gdt = (struct SEGMENT_DESCRIPTOR *) ADR_GDT;
+	struct TASK *task_b;
 
 	init_gdtidt();
 	init_pic();
@@ -96,32 +88,18 @@ void HariMain(void)
 			memtotal / (1024 * 1024), memman_total(memman) / 1024);
 	putfonts8_asc_sht(sht_back, 0, 32, COL8_FFFFFF, COL8_008484, s, 40);
 
-	tss_a.ldtr = 0;
-	tss_a.iomap = 0x40000000;
-	tss_b.ldtr = 0;
-	tss_b.iomap = 0x40000000;
-	set_segmdesc(gdt + 3, 103, (int) &tss_a, AR_TSS32);
-	set_segmdesc(gdt + 4, 103, (int) &tss_b, AR_TSS32);
-	load_tr(3 * 8);
-	task_b_esp = memman_alloc_4k(memman, 64 * 1024) + 64 * 1024 - 8;
-	tss_b.eip = (int) &task_b_main;
-	tss_b.eflags = 0x00000202; /* IF = 1; */
-	tss_b.eax = 0;
-	tss_b.ecx = 0;
-	tss_b.edx = 0;
-	tss_b.ebx = 0;
-	tss_b.esp = task_b_esp;
-	tss_b.ebp = 0;
-	tss_b.esi = 0;
-	tss_b.edi = 0;
-	tss_b.es = 1 * 8;
-	tss_b.cs = 2 * 8;
-	tss_b.ss = 1 * 8;
-	tss_b.ds = 1 * 8;
-	tss_b.fs = 1 * 8;
-	tss_b.gs = 1 * 8;
-	*((int *) (task_b_esp + 4)) = (int) sht_back;
-	mt_init();
+	task_init(memman);
+	task_b = task_alloc();
+	task_b->tss.esp = memman_alloc_4k(memman, 64 * 1024) + 64 * 1024 - 8;
+	task_b->tss.eip = (int) &task_b_main;
+	task_b->tss.es = 1 * 8;
+	task_b->tss.cs = 2 * 8;
+	task_b->tss.ss = 1 * 8;
+	task_b->tss.ds = 1 * 8;
+	task_b->tss.fs = 1 * 8;
+	task_b->tss.gs = 1 * 8;
+	*((int *) (task_b->tss.esp + 4)) = (int) sht_back;
+	task_run(task_b);
 
 	for (;;) {
 		io_cli();
diff --git a/16_day/bootpack.h b/16_day/bootpack.h
index 53e8840..5622ba7 100644
--- a/16_day/bootpack.h
+++ b/16_day/bootpack.h
@@ -185,6 +185,26 @@ void timer_settime(struct TIMER *timer, unsigned int timeout);
 void inthandler20(int *esp);
 
 /* mtask.c */
-extern struct TIMER *mt_timer;
-void mt_init(void);
-void mt_taskswitch(void);
+#define MAX_TASKS 1000	/*最大任务数量*/
+#define TASK_GDT0 3			/*定义从GDT的几号开始分配给TSS */
+struct TSS32 {
+	int backlink, esp0, ss0, esp1, ss1, esp2, ss2, cr3;
+	int eip, eflags, eax, ecx, edx, ebx, esp, ebp, esi, edi;
+	int es, cs, ss, ds, fs, gs;
+	int ldtr, iomap;
+};
+struct TASK {
+	int sel, flags;		/* sel用来存放GDT的编号*/
+	struct TSS32 tss;
+};
+struct TASKCTL {
+	int running;		/*正在运行的任务数量*/
+	int now;				/*这个变量用来记录当前正在运行的是哪个任务*/
+	struct TASK *tasks[MAX_TASKS];
+	struct TASK tasks0[MAX_TASKS];
+};
+extern struct TIMER *task_timer;
+struct TASK *task_init(struct MEMMAN *memman);
+struct TASK *task_alloc(void);
+void task_run(struct TASK *task);
+void task_switch(void);
diff --git a/16_day/mtask.c b/16_day/mtask.c
index ccc5227..a382f22 100644
--- a/16_day/mtask.c
+++ b/16_day/mtask.c
@@ -2,26 +2,78 @@
 
 #include "bootpack.h"
 
-struct TIMER *mt_timer;
-int mt_tr;
+struct TASKCTL *taskctl;
+struct TIMER *task_timer;
 
-void mt_init(void)
+struct TASK *task_init(struct MEMMAN *memman)
 {
-	mt_timer = timer_alloc();
-	/*这里没有必要使用timer_init */
-	timer_settime(mt_timer, 2);
-	mt_tr = 3 * 8;
+	int i;
+	struct TASK *task;
+	struct SEGMENT_DESCRIPTOR *gdt = (struct SEGMENT_DESCRIPTOR *) ADR_GDT;
+	taskctl = (struct TASKCTL *) memman_alloc_4k(memman, sizeof (struct TASKCTL));
+
+	for (i = 0; i < MAX_TASKS; i++) {
+		taskctl->tasks0[i].flags = 0;
+		taskctl->tasks0[i].sel = (TASK_GDT0 + i) * 8;
+		set_segmdesc(gdt + TASK_GDT0 + i, 103, (int) &taskctl->tasks0[i].tss, AR_TSS32);
+	}
+
+	task = task_alloc();
+	task->flags = 2; /*活动中标志*/
+	taskctl->running = 1;
+	taskctl->now = 0;
+	taskctl->tasks[0] = task;
+	load_tr(task->sel);
+	task_timer = timer_alloc();
+	timer_settime(task_timer, 2);
+	return task;
+}
+
+struct TASK *task_alloc(void)
+{
+	int i;
+	struct TASK *task;
+	for (i = 0; i < MAX_TASKS; i++) {
+		if (taskctl->tasks0[i].flags == 0) {
+			task = &taskctl->tasks0[i];
+			task->flags = 1;   /*正在使用的标志*/
+			task->tss.eflags = 0x00000202; /* IF = 1; */
+			task->tss.eax = 0; /*这里先置为0*/
+			task->tss.ecx = 0;
+			task->tss.edx = 0;
+			task->tss.ebx = 0;
+			task->tss.ebp = 0;
+			task->tss.esi = 0;
+			task->tss.edi = 0;
+			task->tss.es = 0;
+			task->tss.ds = 0;
+			task->tss.fs = 0;
+			task->tss.gs = 0;
+			task->tss.ldtr = 0;
+			task->tss.iomap = 0x40000000;
+			return task;
+		}
+	}
+	return 0; /*全部正在使用*/
+}
+
+void task_run(struct TASK *task)
+{
+	task->flags = 2; /*活动中标志*/
+	taskctl->tasks[taskctl->running] = task;
+	taskctl->running++;
 	return;
 }
 
-void mt_taskswitch(void)
+void task_switch(void)
 {
-	if (mt_tr == 3 * 8) {
-		mt_tr = 4 * 8;
-	} else {
-		mt_tr = 3 * 8;
+	timer_settime(task_timer, 2);
+	if (taskctl->running >= 2) {
+		taskctl->now++;
+		if (taskctl->now == taskctl->running) {
+			taskctl->now = 0;
+		}
+		farjmp(0, taskctl->tasks[taskctl->now]->sel);
 	}
-	timer_settime(mt_timer, 2);
-	farjmp(0, mt_tr);
 	return;
-}
\ No newline at end of file
+}
diff --git a/16_day/timer.c b/16_day/timer.c
index 85634b0..f2138aa 100644
--- a/16_day/timer.c
+++ b/16_day/timer.c
@@ -102,7 +102,7 @@ void inthandler20(int *esp)
 		}
 		/* 超时 */
 		timer->flags = TIMER_FLAGS_ALLOC;
-		if (timer != mt_timer) {
+		if (timer != task_timer) {
 			fifo32_put(timer->fifo, timer->data);
 		} else {
 			ts = 1; /* mt_timer超时*/
@@ -112,7 +112,7 @@ void inthandler20(int *esp)
 	timerctl.t0 = timer;
 	timerctl.next = timer->timeout;
 	if (ts != 0) {
-		mt_taskswitch();
+		task_switch();
 	}
 	return;
 }
\ No newline at end of file