diff --git a/07_day/Makefile b/07_day/Makefile
index 199cdee..2bda89c 100644
--- a/07_day/Makefile
+++ b/07_day/Makefile
@@ -1,5 +1,5 @@
 OBJS_BOOTPACK = bootpack.obj naskfunc.obj hankaku.obj graphic.obj dsctbl.obj \
-		int.obj
+		int.obj fifo.obj
 
 TOOLPATH = ../z_tools/
 INCPATH  = ../z_tools/haribote/
diff --git a/07_day/bootpack.c b/07_day/bootpack.c
index aaec63f..dbe463c 100644
--- a/07_day/bootpack.c
+++ b/07_day/bootpack.c
@@ -3,18 +3,19 @@
 #include "bootpack.h"
 #include <stdio.h>
 
-extern struct KEYBUF keybuf;
+extern struct FIFO8 keyfifo;
 
 void HariMain(void)
 {
 	struct BOOTINFO *binfo = (struct BOOTINFO *) ADR_BOOTINFO;
-	char s[40], mcursor[256];
-	int mx, my, i, j;
+	char s[40], mcursor[256], keybuf[32];
+	int mx, my, i;
 
 	init_gdtidt();
 	init_pic();
 	io_sti(); /* IDT/PICの初期化が終わったのでCPUの割り込み禁止を解除 */
 
+	fifo8_init(&keyfifo, 32, keybuf);
 	io_out8(PIC0_IMR, 0xf9); /* PIC1とキーボードを許可(11111001) */
 	io_out8(PIC1_IMR, 0xef); /* マウスを許可(11101111) */
 
@@ -29,15 +30,10 @@ void HariMain(void)
 
 	for (;;) {
 		io_cli();
-		if (keybuf.len == 0) {
+		if (fifo8_status(&keyfifo) == 0) {
 			io_stihlt();
 		} else {
-			i = keybuf.data[keybuf.next_r];
-			keybuf.len--;
-			keybuf.next_r++;
-			if (keybuf.next_r == 32) {
-				keybuf.next_r = 0;
-			}
+			i = fifo8_get(&keyfifo);
 			io_sti();
 			sprintf(s, "%02X", i);
 			boxfill8(binfo->vram, binfo->scrnx, COL8_008484, 0, 16, 15, 31);
diff --git a/07_day/bootpack.h b/07_day/bootpack.h
index 0a9000e..650af9c 100644
--- a/07_day/bootpack.h
+++ b/07_day/bootpack.h
@@ -22,6 +22,16 @@ void asm_inthandler21(void);
 void asm_inthandler27(void);
 void asm_inthandler2c(void);
 
+/* fifo.c */
+struct FIFO8 {
+	unsigned char *buf;
+	int p, q, size, free, flags;
+};
+void fifo8_init(struct FIFO8 *fifo, int size, unsigned char *buf);
+int fifo8_put(struct FIFO8 *fifo, unsigned char data);
+int fifo8_get(struct FIFO8 *fifo);
+int fifo8_status(struct FIFO8 *fifo);
+
 /* graphic.c */
 void init_palette(void);
 void set_palette(int start, int end, unsigned char *rgb);
@@ -74,10 +84,6 @@ void set_gatedesc(struct GATE_DESCRIPTOR *gd, int offset, int selector, int ar);
 #define AR_INTGATE32	0x008e
 
 /* int.c */
-struct KEYBUF {
-	unsigned char data[32];
-	int next_r, next_w, len;
-};
 void init_pic(void);
 void inthandler21(int *esp);
 void inthandler27(int *esp);
diff --git a/07_day/fifo.c b/07_day/fifo.c
new file mode 100644
index 0000000..f582a49
--- /dev/null
+++ b/07_day/fifo.c
@@ -0,0 +1,57 @@
+/* FIFO */
+
+#include "bootpack.h"
+
+#define FLAGS_OVERRUN		0x0001
+
+void fifo8_init(struct FIFO8 *fifo, int size, unsigned char *buf)
+/* 初始化FIFO缓冲区 */
+{
+	fifo->size = size;
+	fifo->buf = buf;
+	fifo->free = size; /* 缓冲区大小 */
+	fifo->flags = 0;
+	fifo->p = 0; /* 下一个数据写入位置 */
+	fifo->q = 0; /* 下一个数据读出位置 */
+	return;
+}
+
+int fifo8_put(struct FIFO8 *fifo, unsigned char data)
+/* 向FIFO传送数据并保存 */
+{
+	if (fifo->free == 0) {
+		/* 没有空间了，溢出 */
+		fifo->flags |= FLAGS_OVERRUN;
+		return -1;
+	}
+	fifo->buf[fifo->p] = data;
+	fifo->p++;
+	if (fifo->p == fifo->size) {
+		fifo->p = 0;
+	}
+	fifo->free--;
+	return 0;
+}
+
+int fifo8_get(struct FIFO8 *fifo)
+/* 从FIFO取得一个数据 */
+{
+	int data;
+	if (fifo->free == fifo->size) {
+		/* 如果缓冲区为空则返回-1 */
+		return -1;
+	}
+	data = fifo->buf[fifo->q];
+	fifo->q++;
+	if (fifo->q == fifo->size) {
+		fifo->q = 0;
+	}
+	fifo->free++;
+	return data;
+}
+
+int fifo8_status(struct FIFO8 *fifo)
+/* 报告一下积攒是数据量 */
+{
+	return fifo->size - fifo->free;
+}
diff --git a/07_day/int.c b/07_day/int.c
index bd4a18c..c8595e5 100644
--- a/07_day/int.c
+++ b/07_day/int.c
@@ -26,7 +26,7 @@ void init_pic(void)
 
 #define PORT_KEYDAT		0x0060
 
-struct KEYBUF keybuf;
+struct FIFO8 keyfifo;
 
 void inthandler21(int *esp)
 /* 来自PS/2键盘的中断 */
@@ -35,14 +35,7 @@ void inthandler21(int *esp)
 	unsigned char data, s[4];
 	io_out8(PIC0_OCW2, 0x61);	/* 通知PIC IRQ-01 已经受理完毕 */
 	data = io_in8(PORT_KEYDAT);
-	if (keybuf.len < 32) {
-		keybuf.data[keybuf.next_w] = data;
-		keybuf.len++;
-		keybuf.next_w++;
-		if (keybuf.next_w == 32) {
-			keybuf.next_w = 0;
-		}
-	}
+	fifo8_put(&keyfifo, data);
 	return;
 }