diff --git a/21_day/Makefile b/21_day/Makefile
index aa474f4..6c408b7 100644
--- a/21_day/Makefile
+++ b/21_day/Makefile
@@ -73,8 +73,11 @@ crack1.bim : crack1.obj Makefile
 crack1.hrb : crack1.bim Makefile
 	$(BIM2HRB) crack1.bim crack1.hrb 0
 
+crack2.hrb : crack2.nas Makefile
+	$(NASK) crack2.nas crack2.hrb crack2.lst
+
 haribote.img : ipl10.bin haribote.sys Makefile \
-		hello.hrb hello2.hrb a.hrb hello3.hrb crack1.hrb
+		hello.hrb hello2.hrb a.hrb hello3.hrb crack1.hrb crack2.hrb
 	$(EDIMG)   imgin:../z_tools/fdimg0at.tek \
 		wbinimg src:ipl10.bin len:512 from:0 to:0 \
 		copy from:haribote.sys to:@: \
@@ -85,6 +88,7 @@ haribote.img : ipl10.bin haribote.sys Makefile \
 		copy from:a.hrb to:@: \
 		copy from:hello3.hrb to:@: \
 		copy from:crack1.hrb to:@: \
+		copy from:crack2.hrb to:@: \
 		imgout:haribote.img
 		
 # 其他指令
diff --git a/21_day/crack2.nas b/21_day/crack2.nas
new file mode 100644
index 0000000..f9b467c
--- /dev/null
+++ b/21_day/crack2.nas
@@ -0,0 +1,6 @@
+[INSTRSET "i486p"]
+[BITS 32]
+		MOV		EAX,1*8			; OS用的段号
+		MOV		DS,AX				; 将其存入DS
+		MOV		BYTE [0x102600],0
+		RETF