diff --git a/libs/master.lib/keybios.asm b/libs/master.lib/keybios.asm
new file mode 100644
index 00000000..b0efeab2
--- /dev/null
+++ b/libs/master.lib/keybios.asm
@@ -0,0 +1,60 @@
+; master library - PC-9801
+;
+; Description:
+;	PC-9801の KEY BIOS を用いて、キーバッファの先頭の値を取り出す
+;
+; Function/Procedures:
+;	unsigned key_wait_bios(void) ;
+;	unsigned key_sense_bios(void) ;
+;
+; Parameters:
+;	none
+;
+; Returns:
+;	上位8bit:キーコード
+;	下位8bit:キーデータ(キャラクタコード)
+;
+;	key_wait_bios:	キー入力が無ければ押されるまで待ち、バッファから
+;			取り除く。
+;	key_sense_bios:	キー入力が無ければ、0を返す。キー入力がある場合も
+;			バッファの更新は行わない。
+;
+; Binding Target:
+;	Microsoft-C / Turbo-C / Turbo Pascal
+;
+; Running Target:
+;	PC-9801
+;
+; Requiring Resources:
+;	CPU: 8086
+;
+; Notes:
+;	
+;
+; Assembly Language Note:
+;	
+;
+; Compiler/Assembler:
+;	TASM 3.0
+;	OPTASM 1.6
+;
+; Author:
+;	恋塚昭彦
+;
+; Revision History:
+;	93/ 8/17 Initial: keybios.asm/master.lib 0.21
+
+func KEY_WAIT_BIOS	; key_wait_bios() {
+	mov	AH,0
+	int	18h
+	ret
+endfunc		; }
+
+func KEY_SENSE_BIOS	; key_sense_bios() {
+	mov	AH,1
+	int	18h
+	shr	BH,1
+	sbb	BX,BX
+	and	AX,BX
+	ret
+endfunc		; }
diff --git a/th01_op.asm b/th01_op.asm
index 6c4d9888..bc9d7e51 100644
--- a/th01_op.asm
+++ b/th01_op.asm
@@ -1907,29 +1907,7 @@ loc_129F:
 locret_12A8:
 		retf
 ; ---------------------------------------------------------------------------
-		nop
-		mov	ah, 0
-		int	18h		; TRANSFER TO ROM BASIC
-					; causes transfer to ROM-based BASIC (IBM-PC)
-					; often	reboots	a compatible; often has	no effect at all
-		retf
-; ---------------------------------------------------------------------------
-		nop
-
-; =============== S U B	R O U T	I N E =======================================
-
-
-sub_12B0	proc far
-		mov	ah, 1
-		int	18h		; TRANSFER TO ROM BASIC
-					; causes transfer to ROM-based BASIC (IBM-PC)
-					; often	reboots	a compatible; often has	no effect at all
-		shr	bh, 1
-		sbb	bx, bx
-		and	ax, bx
-		retf
-sub_12B0	endp
-
+include libs/master.lib/keybios.asm
 include libs/master.lib/dos_ropen.asm
 include libs/master.lib/egc.asm
 include libs/master.lib/random.asm
@@ -9074,7 +9052,7 @@ loc_B126:
 		inc	di
 
 loc_B135:
-		call	sub_12B0
+		call	key_sense_bios
 		or	ax, ax
 		jz	short loc_B126
 		push	cs