diff --git a/th01_reiiden.asm b/th01_reiiden.asm
index 990a9c46..b075af1b 100644
--- a/th01_reiiden.asm
+++ b/th01_reiiden.asm
@@ -1007,7 +1007,7 @@ loc_BF6E:
 loc_BF75:
 		cmp	si, COLOR_COUNT
 		jl	short loc_BF15
-		mov	byte_3876C, 0FFh
+		mov	byte_3876C, -1
 		jmp	loc_C42E
 ; ---------------------------------------------------------------------------
 
@@ -1585,7 +1585,7 @@ arg_0		= word ptr  6
 		push	si
 		cmp	[bp+arg_0], 0
 		jnz	short loc_C4AB
-		cmp	word_387DA, 0FFh
+		cmp	word_387DA, 255
 		jz	loc_C5B1
 		xor	si, si
 		jmp	short loc_C49D
@@ -1606,12 +1606,12 @@ loc_C47E:
 loc_C49D:
 		cmp	si, 8
 		jl	short loc_C47E
-		mov	word_387DA, 0FFh
+		mov	word_387DA, 255
 		jmp	loc_C5B1
 ; ---------------------------------------------------------------------------
 
 loc_C4AB:
-		cmp	word_387DA, 0FFh
+		cmp	word_387DA, 255
 		jnz	short loc_C4C7
 		xor	si, si
 		jmp	short loc_C4C2
@@ -5214,7 +5214,7 @@ loc_11B26:
 		add	bx, dx
 		cmp	al, es:[bx+si]
 		jle	short loc_11B62
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_11B64
 ; ---------------------------------------------------------------------------
 
@@ -10583,7 +10583,7 @@ arg_20		= dword	ptr  26h
 		cbw
 		cmp	ax, 1
 		jnz	loc_17F73
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		les	bx, [bp+arg_16]
@@ -10615,7 +10615,7 @@ arg_20		= dword	ptr  26h
 ; ---------------------------------------------------------------------------
 
 loc_17F3C:
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	7
@@ -12240,7 +12240,7 @@ arg_0		= word ptr  6
 		mov	byte_35B42, 0
 		mov	byte_35B43, 0
 		mov	byte_35B44, 0
-		mov	byte_39DB2, 0FFh
+		mov	byte_39DB2, -1
 		mov	byte_35B45, 1
 		mov	byte_35B46, 0
 		mov	byte_34A58, 0
@@ -20235,7 +20235,7 @@ arg_0		= word ptr  6
 		push	si
 		cmp	[bp+arg_0], 0
 		jnz	short loc_1EFB1
-		mov	byte_39E25, 0FFh
+		mov	byte_39E25, -1
 		mov	byte_35B7B, 4
 		call	IRand
 		mov	bx, 2
@@ -20247,7 +20247,7 @@ arg_0		= word ptr  6
 ; ---------------------------------------------------------------------------
 
 loc_1EFB1:
-		cmp	byte_39E25, 0FFh
+		cmp	byte_39E25, -1
 		jnz	short loc_1EFE5
 		push	1
 		call	_graph_accesspage_func
@@ -20385,7 +20385,7 @@ loc_1F0F8:
 		call	@CBossEntity@put_8$xqiii stdcall, offset mima_still, ds, large [dword ptr mima_still.BE_cur_left], 0
 		call	_z_palette_set_all_show stdcall, offset palette_39B8C, ds
 		add	sp, 1Ch
-		mov	byte_39E25, 0FFh
+		mov	byte_39E25, -1
 		mov	al, 1
 		sub	al, byte_39E26
 		mov	byte_39E26, al
@@ -20628,7 +20628,7 @@ loc_1F322:
 		add	bx, bx
 		cmp	word ptr [bx+5487h], 20h ; ' '
 		jle	short loc_1F380
-		push	0FFh
+		push	255
 		push	0
 		push	4
 		mov	bx, si
@@ -20703,7 +20703,7 @@ loc_1F3DD:
 		add	bx, bx
 		cmp	word ptr [bx+5487h], 20h ; ' '
 		jle	short loc_1F458
-		push	0FFh
+		push	255
 		push	0
 		push	4
 		push	7
@@ -22829,7 +22829,7 @@ arg_0		= byte ptr  6
 loc_2079C:
 		push	ds
 		mov	ax, si
-		imul	ax, 0FFh
+		imul	ax, 255
 		add	ax, 228Eh
 		push	ax
 		push	250
@@ -23076,7 +23076,7 @@ loc_20952:
 
 loc_20957:
 		mov	bx, [bp+arg_0]
-		imul	bx, 0FFh
+		imul	bx, 255
 		mov	al, [bx+di+228Eh]
 		cbw
 		test	ax, si
@@ -23100,7 +23100,7 @@ loc_20972:
 
 loc_2097C:
 		mov	bx, [bp+arg_0]
-		imul	bx, 0FFh
+		imul	bx, 255
 		mov	al, [bx+di+228Eh]
 		cbw
 		dec	ax
@@ -23269,7 +23269,7 @@ loc_20AEB:
 
 loc_20AF0:
 		mov	bx, [bp+arg_0]
-		imul	bx, 0FFh
+		imul	bx, 255
 		mov	al, [bx+di+228Eh]
 		cbw
 		test	ax, si
@@ -23333,7 +23333,7 @@ loc_20B79:
 
 loc_20B8B:
 		mov	bx, [bp+arg_0]
-		imul	bx, 0FFh
+		imul	bx, 255
 		mov	al, [bx+di+228Eh]
 		cbw
 		dec	ax
@@ -23392,7 +23392,7 @@ loc_20BE1:
 		cmp	ax, [bp+var_A]
 		jnz	short loc_20C20
 		mov	bx, [bp+arg_0]
-		imul	bx, 0FFh
+		imul	bx, 255
 		mov	al, [bx+di+228Eh]
 		add	al, 0F3h
 		les	bx, off_39E96
@@ -23454,7 +23454,7 @@ loc_20C59:
 		call	sub_207BD
 		add	sp, 8
 		mov	bx, [bp+arg_0]
-		imul	bx, 0FFh
+		imul	bx, 255
 		mov	al, [bx+di+228Eh]
 		mov	bx, [bp+var_E]
 		mov	es, word ptr off_39EA2+2
@@ -26058,7 +26058,7 @@ arg_2		= word ptr  8
 		enter	2, 0
 		push	si
 		mov	si, [bp+arg_0]
-		cmp	si, 0FFh
+		cmp	si, 255
 		jnz	short loc_2229C
 		mov	[bp+var_1], 0
 		jmp	short loc_22287
@@ -26972,7 +26972,7 @@ sub_229D1	proc far
 ; ---------------------------------------------------------------------------
 
 loc_229EF:
-		mov	al, 0FFh
+		mov	al, -1
 
 loc_229F1:
 		mov	byte_3A388, al
@@ -31479,7 +31479,7 @@ var_8		= qword	ptr -8
 loc_2546B:
 		cmp	word_3A6CA, 3Ch	; '<'
 		jnz	short loc_254A0
-		push	0FFh
+		push	255
 		push	0
 		push	2
 		push	40020h
@@ -31507,7 +31507,7 @@ loc_254A0:
 		idiv	bx
 		or	dx, dx
 		jnz	short loc_25528
-		push	0FFh
+		push	255
 		push	0
 		push	2
 		push	word_3A6E3
@@ -31521,7 +31521,7 @@ loc_254A0:
 		call	sub_17956
 		add	sp, 0Eh
 		add	word_3A6E3, 8
-		push	0FFh
+		push	255
 		push	0
 		cmp	word_3A6CA, 64h	; 'd'
 		jge	short loc_254F7
@@ -31558,7 +31558,7 @@ loc_25504:
 loc_25528:
 		cmp	word_3A6CA, 78h	; 'x'
 		jnz	short loc_25556
-		push	0FFh
+		push	255
 		push	0
 		push	20h ; ' '
 		push	word_3A6E3
@@ -32042,7 +32042,7 @@ loc_25977:
 		mov	angle_3A6FB, al
 		cmp	angle_3A6FB, 40h
 		jb	loc_25C4A
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -32053,7 +32053,7 @@ loc_25977:
 		add	ax, 64
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	70080h
@@ -32096,7 +32096,7 @@ loc_25AED:
 		idiv	bx
 		or	dx, dx
 		jnz	short loc_25B3E
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -32108,7 +32108,7 @@ loc_25AED:
 		push	ax
 		call	sub_17956
 		add	sp, 0Eh
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	4
@@ -32122,7 +32122,7 @@ loc_25B3E:
 		idiv	bx
 		cmp	dx, 4
 		jnz	loc_25C4A
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -32134,7 +32134,7 @@ loc_25B3E:
 		push	ax
 		call	sub_17956
 		add	sp, 0Eh
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	7
@@ -32155,7 +32155,7 @@ loc_25B7A:
 loc_25B99:
 		cmp	word_3A6FC, 0
 		jz	loc_25C4A
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -32554,7 +32554,7 @@ loc_25EE1:
 		call	sub_1786D
 		add	sp, 30h
 		mov	al, byte ptr word_3A6FE
-		add	al, 0C2h ; '?'
+		add	al, 194
 		push	ax
 		mov	al, byte ptr word_3A6FE
 		add	al, 0C0h ; '?'
@@ -32576,7 +32576,7 @@ loc_25EE1:
 		cmp	byte ptr word_3A6FE, 40h
 		jb	loc_260D8
 		mov	word_3A6FE+1, 1
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -32587,7 +32587,7 @@ loc_25EE1:
 		add	ax, 64
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	70080h
@@ -32623,7 +32623,7 @@ loc_26006:
 		jnz	short loc_26029
 		push	bx
 		call	sub_25DE6
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	4
@@ -32641,7 +32641,7 @@ loc_26029:
 		jnz	short loc_26068
 		push	7
 		call	sub_25DE6
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	7
@@ -32678,7 +32678,7 @@ loc_26068:
 		push	96h
 		push	0EAh
 		call	sub_25CFD
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -34728,7 +34728,7 @@ loc_27317:
 		mov	angle_3A76F, al
 		cmp	angle_3A76F, 40h
 		jb	loc_275EF
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -34737,7 +34737,7 @@ loc_27317:
 		add	ax, 10h
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	70080h
@@ -34780,7 +34780,7 @@ loc_27464:
 		idiv	bx
 		or	dx, dx
 		jnz	short loc_274C6
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -34789,7 +34789,7 @@ loc_27464:
 		add	ax, 10h
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	70080h
@@ -34881,7 +34881,7 @@ loc_27572:
 		jl	short loc_275EF
 		cmp	word_3A76B, 0C8h ; '?'
 		jnz	short loc_275A1
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -35097,7 +35097,7 @@ loc_27759:
 		mov	angle_3A770, al
 		cmp	angle_3A770, 40h
 		jb	loc_27A1C
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -35108,7 +35108,7 @@ loc_27759:
 		add	ax, 64
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	70080h
@@ -35151,7 +35151,7 @@ loc_278BE:
 		idiv	bx
 		or	dx, dx
 		jnz	short loc_2790F
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -35163,7 +35163,7 @@ loc_278BE:
 		push	ax
 		call	sub_17956
 		add	sp, 0Eh
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	4
@@ -35177,7 +35177,7 @@ loc_2790F:
 		idiv	bx
 		cmp	dx, 4
 		jnz	loc_27A1C
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -35189,7 +35189,7 @@ loc_2790F:
 		push	ax
 		call	sub_17956
 		add	sp, 0Eh
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	7
@@ -35210,7 +35210,7 @@ loc_2794B:
 loc_2796A:
 		cmp	word_3A771, 0
 		jz	loc_27A1C
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	800080h
@@ -38328,7 +38328,7 @@ loc_295EF:
 		idiv	bx
 		or	dx, dx
 		jz	short loc_29665
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	[bp+var_2]
@@ -38349,7 +38349,7 @@ loc_29665:
 		idiv	bx
 		cmp	dx, 8
 		jz	short loc_296EC
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	4
@@ -38979,7 +38979,7 @@ loc_29BE7:
 		lea	ax, [bp+var_18]
 		add	si, ax
 		mov	ax, ss:[si]
-		and	ax, 0FFh
+		and	ax, 11111111b
 		mov	es:[bx], ax
 
 loc_29C15:
@@ -39053,7 +39053,7 @@ loc_29C2A:
 		lea	ax, [bp+var_E]
 		add	si, ax
 		mov	ax, ss:[si]
-		and	ax, 0FFh
+		and	ax, 11111111b
 		mov	es:[bx], ax
 
 loc_29CAB:
@@ -39476,7 +39476,7 @@ loc_2A0B0:
 loc_2A0CF:
 		cmp	word_35E03, 3
 		jnz	loc_2A16A
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	60010h
@@ -39485,7 +39485,7 @@ loc_2A0CF:
 		sar	ax, 4
 		push	ax
 		call	sub_1786D
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	60030h
@@ -39494,7 +39494,7 @@ loc_2A0CF:
 		sar	ax, 4
 		push	ax
 		call	sub_1786D
-		push	0FFh
+		push	255
 		push	0
 		push	6
 		push	70018h
@@ -39534,7 +39534,7 @@ loc_2A175:
 		or	dx, dx
 		jnz	loc_2A2BA
 		call	_egc_copy_rect_1_to_0_16 stdcall, x_3AF34, y_3AF38, 16, bx
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	word_3AF40
@@ -39544,7 +39544,7 @@ loc_2A175:
 		sar	ax, 4
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	word_3AF3E
@@ -39554,7 +39554,7 @@ loc_2A175:
 		sar	ax, 4
 		push	ax
 		call	sub_17956
-		push	0FFh
+		push	255
 		push	0
 		push	6
 		push	word_3AF42
@@ -39592,7 +39592,7 @@ loc_2A175:
 ; ---------------------------------------------------------------------------
 
 loc_2A245:
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	5
@@ -39603,7 +39603,7 @@ loc_2A245:
 		sar	ax, 4
 		push	ax
 		call	sub_1786D
-		push	0FFh
+		push	255
 		push	0
 		push	8
 		push	5
@@ -39614,7 +39614,7 @@ loc_2A245:
 		sar	ax, 4
 		push	ax
 		call	sub_1786D
-		push	0FFh
+		push	255
 		push	0
 		push	6
 		push	7
@@ -41195,7 +41195,7 @@ loc_2B2D1:
 		idiv	di
 		or	dx, dx
 		jnz	short loc_2B349
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	word_3B053
@@ -41211,7 +41211,7 @@ loc_2B2D1:
 ; ---------------------------------------------------------------------------
 
 loc_2B30B:
-		push	0FFh
+		push	255
 		push	0
 		push	1
 		push	[bp+arg_4]
@@ -46288,7 +46288,7 @@ loc_2E580:
 ; ---------------------------------------------------------------------------
 
 loc_2E589:
-		cmp	word_3A6CA, 0FFh
+		cmp	word_3A6CA, 255
 		jge	short loc_2E5B0
 		call	sub_2CE17 c, large (70 shl 16) or 410, point_3B511.x, point_3B511.y, 6
 		sub	point_3B511.y, 8
@@ -46296,7 +46296,7 @@ loc_2E589:
 ; ---------------------------------------------------------------------------
 
 loc_2E5B0:
-		cmp	word_3A6CA, 0FFh
+		cmp	word_3A6CA, 255
 		jnz	short loc_2E5E9
 		mov	point_3B511.x, RES_X - 1
 		mov	point_3B511.y, 64
diff --git a/th02_main.asm b/th02_main.asm
index 598e320e..5f8e3272 100644
--- a/th02_main.asm
+++ b/th02_main.asm
@@ -230,7 +230,7 @@ loc_3DED:
 		mov	word_1FFF4, 0
 		mov	byte_1FFF8, 0Fh
 		mov	byte_1FFF9, 0
-		mov	byte_1FFFA, 0FFh
+		mov	byte_1FFFA, -1
 		mov	word_1FFF6, 20h	; ' '
 		pop	bp
 		retf
@@ -3079,7 +3079,7 @@ loc_C015:
 		mov	eax, _boss_update_func
 		mov	_boss_update, eax
 		setfarfp	farfp_1F48C, sub_BF9C
-		mov	byte_20343, 0FFh
+		mov	byte_20343, -1
 		mov	bgm_show_timer, 1
 		mov	al, byte_1F46E
 		mov	_bgm_title_id, al
@@ -6013,7 +6013,7 @@ arg_2		= word ptr  6
 		mov	[bp+var_14], al
 		cmp	point_205F6.x, 128
 		jg	short loc_D794
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_D7A2
 ; ---------------------------------------------------------------------------
 
@@ -6563,7 +6563,7 @@ loc_DBFE:
 		cmp	ax, RANK_HARD
 		jl	short loc_DC28
 		mov	cl, _rank
-		add	cl, 0FFh
+		add	cl, -1
 		mov	eax, dword_218A4
 		shl	eax, cl
 		mov	dword_218A4, eax
@@ -8541,7 +8541,7 @@ loc_EE0B:
 		mov	cx, 4
 		mov	dx, 10h
 		mov	bx, [bp+arg_0]
-		mov	al, 0FFh
+		mov	al, 11111111b
 
 loc_EE2E:
 		mov	es:[di], al
@@ -8735,7 +8735,7 @@ loc_EF5F:
 		cmp	_player_is_hit, 0
 		jz	short loc_EF7F
 		call	sub_EFF2
-		cmp	_player_is_hit, 0FFh
+		cmp	_player_is_hit, -1
 		jnz	short loc_EFEF
 		mov	byte_20607, 1
 		mov	_player_is_hit, 0
@@ -8888,7 +8888,7 @@ loc_F0B9:
 		push	word ptr [bx]
 		call	sub_D743
 		mov	byte_218A1, 0
-		mov	_player_is_hit, 0FFh
+		mov	_player_is_hit, -1
 		jmp	loc_F1D5
 ; ---------------------------------------------------------------------------
 
@@ -9166,7 +9166,7 @@ loc_F2FB:
 		mov	[bx], ax
 		test	byte ptr _key_det, INPUT_SHOT
 		jz	short loc_F349
-		cmp	byte_1EB0D, 0FFh
+		cmp	byte_1EB0D, -1
 		jnz	short loc_F336
 		mov	byte_1EB0D, 0
 		mov	byte_22D4A, 0
@@ -9174,7 +9174,7 @@ loc_F2FB:
 ; ---------------------------------------------------------------------------
 
 loc_F336:
-		cmp	byte_1EB0E, 0FFh
+		cmp	byte_1EB0E, -1
 		jnz	short loc_F368
 		mov	byte_1EB0E, 0
 		mov	byte_22D4B, 0
@@ -9184,7 +9184,7 @@ loc_F336:
 loc_F349:
 		cmp	byte_1EB0D, 3
 		jb	short loc_F35C
-		mov	byte_1EB0D, 0FFh
+		mov	byte_1EB0D, -1
 		mov	byte_1EB0E, 4
 		jmp	short loc_F368
 ; ---------------------------------------------------------------------------
@@ -9192,10 +9192,10 @@ loc_F349:
 loc_F35C:
 		cmp	byte_1EB0E, 2
 		jb	short loc_F368
-		mov	byte_1EB0E, 0FFh
+		mov	byte_1EB0E, -1
 
 loc_F368:
-		cmp	byte_1EB0D, 0FFh
+		cmp	byte_1EB0D, -1
 		jz	short loc_F3B3
 		cmp	byte_22D4A, 0
 		jnz	short loc_F3AF
@@ -15678,7 +15678,7 @@ loc_12F59:
 		sub	[bp+var_4], 190h
 
 loc_12F6E:
-		cmp	di, 0FFh
+		cmp	di, 255
 		jnz	short loc_12F94
 		call	grcg_setcolor pascal, (GC_RMW shl 16) + 0
 		push	40
@@ -16435,11 +16435,11 @@ sub_13439	endp
 sub_134A0	proc near
 		push	bp
 		mov	bp, sp
-		push	0FFh
+		push	255
 		call	sub_13055
 		push	0
 		call	sub_13055
-		push	0FFh
+		push	255
 		call	sub_13055
 		pop	bp
 		retn
@@ -20906,7 +20906,7 @@ loc_15B65:
 		add	ax, 64
 		cwd
 		idiv	bx
-		add	al, 0FFh
+		add	al, -1
 		mov	byte_25590, al
 		mov	patnum_2064E, 134
 		jmp	loc_15D51
@@ -21091,7 +21091,7 @@ var_1		= byte ptr -1
 ; ---------------------------------------------------------------------------
 
 loc_15D7E:
-		mov	al, 0FFh
+		mov	al, -1
 
 loc_15D80:
 		mov	byte_25597, al
@@ -21295,7 +21295,7 @@ loc_15F06:
 ; ---------------------------------------------------------------------------
 
 loc_15F19:
-		mov	al, 0FFh
+		mov	al, -1
 
 loc_15F1B:
 		mov	byte_25598, al
@@ -23226,7 +23226,7 @@ loc_16FD2:
 		add	bx, word_26C44
 		cmp	byte ptr [bx+2], 0
 		jnz	short loc_16FE7
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_16FE9
 ; ---------------------------------------------------------------------------
 
@@ -23247,7 +23247,7 @@ loc_16FFA:
 		mov	bx, word_26C46
 		cmp	word ptr [bx+18h], 1
 		jnz	short loc_17008
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_1700A
 ; ---------------------------------------------------------------------------
 
@@ -25488,7 +25488,7 @@ arg_4		= dword	ptr  8
 		shl	word_26CCC, 4
 		shl	word_26CCE, 4
 		mov	word_26CD0, 4
-		mov	byte_26CD3, 0FFh
+		mov	byte_26CD3, -1
 		mov	byte_26CD4, 0
 		jmp	loc_1889C
 ; ---------------------------------------------------------------------------
@@ -25825,7 +25825,7 @@ loc_18783:
 loc_18791:
 		cmp	word_26CD0, 80h
 		jle	short loc_1879E
-		mov	byte_26CD3, 0FEh
+		mov	byte_26CD3, -2
 
 loc_1879E:
 		mov	ax, word_26CCC
@@ -26391,7 +26391,7 @@ loc_18C9B:
 		mov	byte_26CE2, al
 		cmp	point_205F6.x, 208
 		jg	short loc_18CDF
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_18CE1
 ; ---------------------------------------------------------------------------
 
@@ -30584,7 +30584,7 @@ sub_1B555	proc near
 ; ---------------------------------------------------------------------------
 
 loc_1B579:
-		mov	al, 0FFh
+		mov	al, -1
 
 loc_1B57B:
 		mov	byte_26D81, al
@@ -30994,7 +30994,7 @@ loc_1B8C5:
 		add	ax, 16
 		push	ax
 		push	word_26D87+1
-		push	0FFh
+		push	255
 		push	55003Ch
 		call	sub_10865
 		jmp	loc_1B992
@@ -31460,7 +31460,7 @@ loc_1BD46:
 		add	ax, 8
 		push	ax
 		push	0C0h
-		push	0FFh
+		push	255
 		push	550046h
 		call	sub_10865
 
@@ -31477,7 +31477,7 @@ loc_1BD86:
 		add	ax, 40
 		push	ax
 		push	0C0h
-		push	0FFh
+		push	255
 		push	550046h
 		call	sub_10865
 		jmp	loc_1BE2F
@@ -31515,7 +31515,7 @@ loc_1BDC4:
 		push	dx
 		push	10h
 		push	[bp+var_3]
-		push	0FFh
+		push	255
 		push	55h ; 'U'
 		call	randring2_next8_and pascal, 1Fh
 		mov	ah, 0
@@ -31530,7 +31530,7 @@ loc_1BDC4:
 		add	dx, 10h
 		push	dx
 		push	[bp+var_3]
-		push	0FFh
+		push	255
 		push	55h ; 'U'
 		call	randring2_next8_and pascal, 1Fh
 		mov	ah, 0
@@ -31904,7 +31904,7 @@ loc_1C0F2:
 		mov	bx, 3
 		cwd
 		idiv	bx
-		mov	al, 0FFh
+		mov	al, 255
 		sub	al, dl
 		mov	byte_26D4D, al
 
@@ -32374,7 +32374,7 @@ loc_1C473:
 		mov	bx, [bx+7F0Eh]
 		add	bx, bx
 		mov	ax, [bx+1EDAh]
-		and	ax, 0FFh
+		and	ax, 255
 		mov	bx, word ptr [bp+dest]
 		mov	[bx+1Eh], ax
 		mov	ax, [bx+1Ah]
@@ -32430,7 +32430,7 @@ loc_1C518:
 		inc	word ptr [bp+src]
 		inc	[bp+var_4]
 		les	bx, [bp+src]
-		cmp	byte ptr es:[bx], 0FFh
+		cmp	byte ptr es:[bx], -1
 		jnz	short loc_1C518
 		inc	word ptr [bp+src]
 		mov	al, byte_22FDB
@@ -32501,7 +32501,7 @@ loc_1C5BD:
 		push	es
 		push	bx
 		les	bx, [bp+src]
-		cmp	byte ptr es:[bx], 0FFh
+		cmp	byte ptr es:[bx], -1
 		jnz	short loc_1C5DD
 		mov	ax, 0FFFFh
 		jmp	short loc_1C5E5
@@ -33984,8 +33984,8 @@ asc_1E6DF	db '  ',0
 include th02/sprites/sparks.asp
 word_1EB0A	dw 0
 byte_1EB0C	db 0
-byte_1EB0D	db 0FFh
-byte_1EB0E	db 0FFh
+byte_1EB0D	db -1
+byte_1EB0E	db -1
 		db    1
 		db    1
 		db    4
diff --git a/th03_main.asm b/th03_main.asm
index 03d3073b..e9b2e9bc 100644
--- a/th03_main.asm
+++ b/th03_main.asm
@@ -632,7 +632,7 @@ loc_9BC5:
 		jz	short loc_9BF4
 
 loc_9BEF:
-		mov	byte_220DC, 0FFh
+		mov	byte_220DC, -1
 
 loc_9BF4:
 		les	bx, _resident
@@ -684,7 +684,7 @@ loc_9C51:
 		mov	_p2.cpu_safety_frames, ax
 		mov	byte_202B6, 1
 		mov	byte_202B7, 1
-		mov	byte_220DC, 0FFh
+		mov	byte_220DC, -1
 		mov	_cpu_hit_damage_additional, 0
 		push	3
 
@@ -1175,7 +1175,7 @@ loc_A10B:
 		mov	byte_202B7, 10h
 
 loc_A117:
-		mov	byte_1DB9E, 0FFh
+		mov	byte_1DB9E, -1
 		mov	byte_20E3C, 0
 		mov	byte_207E2, 1
 		mov	word_21434, 1400h
@@ -3952,7 +3952,7 @@ loc_C159:
 		add	ax, ax
 		mov	bx, ax
 		mov	_playfield_fg_shift_x[bx], 0
-		mov	byte ptr [si+1Fh], 0FFh
+		mov	byte ptr [si+1Fh], -1
 		mov	PaletteTone, 100
 		call	far ptr	palette_show
 		mov	byte_20E3C, 2
@@ -5055,28 +5055,28 @@ loc_C956:
 		mov	cx, [bp+var_4]
 		or	cx, cx
 		jz	short loc_C9A6
-		cmp	cx, 40h
+		cmp	cx, 64
 		jnb	short loc_C968
 		mov	[bp+var_1], 0Fh
 		jmp	short loc_C990
 ; ---------------------------------------------------------------------------
 
 loc_C968:
-		cmp	cx, 80h
+		cmp	cx, 128
 		jnb	short loc_C974
 		mov	[bp+var_1], 0Ah
 		jmp	short loc_C990
 ; ---------------------------------------------------------------------------
 
 loc_C974:
-		cmp	cx, 0C0h
+		cmp	cx, 192
 		jnb	short loc_C980
 		mov	[bp+var_1], 8
 		jmp	short loc_C990
 ; ---------------------------------------------------------------------------
 
 loc_C980:
-		cmp	cx, 0FFh
+		cmp	cx, 255
 		jnb	short loc_C98C
 		mov	[bp+var_1], 6
 		jmp	short loc_C990
@@ -5099,28 +5099,28 @@ loc_C9A6:
 		mov	cx, [bp+var_6]
 		or	cx, cx
 		jz	short loc_C9F6
-		cmp	cx, 40h
+		cmp	cx, 64
 		jnb	short loc_C9B8
 		mov	[bp+var_1], 0Fh
 		jmp	short loc_C9E0
 ; ---------------------------------------------------------------------------
 
 loc_C9B8:
-		cmp	cx, 80h
+		cmp	cx, 128
 		jnb	short loc_C9C4
 		mov	[bp+var_1], 0Ah
 		jmp	short loc_C9E0
 ; ---------------------------------------------------------------------------
 
 loc_C9C4:
-		cmp	cx, 0C0h
+		cmp	cx, 192
 		jnb	short loc_C9D0
 		mov	[bp+var_1], 8
 		jmp	short loc_C9E0
 ; ---------------------------------------------------------------------------
 
 loc_C9D0:
-		cmp	cx, 0FFh
+		cmp	cx, 255
 		jnb	short loc_C9DC
 		mov	[bp+var_1], 6
 		jmp	short loc_C9E0
@@ -6592,7 +6592,7 @@ loc_D56B:
 		inc	byte_220DC
 		cmp	byte_220DC, 2
 		jnz	short locret_D5A0
-		mov	byte_220DC, 0FFh
+		mov	byte_220DC, -1
 
 locret_D5A0:
 		retn
@@ -7386,14 +7386,14 @@ loc_DB0A:
 ; ---------------------------------------------------------------------------
 
 loc_DB1E:
-		cmp	byte_20E48, 0FFh
+		cmp	byte_20E48, -1
 		jnz	short loc_DB2B
 		mov	[bp+var_5], 20h	; ' '
 		jmp	short loc_DB3C
 ; ---------------------------------------------------------------------------
 
 loc_DB2B:
-		cmp	byte_20E48, 0FEh
+		cmp	byte_20E48, -2
 		jnz	short loc_DB38
 		mov	[bp+var_5], 7
 		jmp	short loc_DB3C
@@ -7560,7 +7560,7 @@ loc_DC64:
 
 loc_DCBC:
 		add	word_21434, 2800h
-		cmp	byte_1DB9E, 0FFh
+		cmp	byte_1DB9E, -1
 		jnz	short loc_DCCE
 		inc	byte ptr [si+77h]
 		jmp	short loc_DD2B
@@ -7739,7 +7739,7 @@ loc_DE3F:
 ; ---------------------------------------------------------------------------
 
 loc_DE45:
-		cmp	byte ptr [si+1Fh], 0FFh
+		cmp	byte ptr [si+1Fh], -1
 		jz	short loc_DE4F
 		push	si
 		call	sub_C0D8
@@ -7804,7 +7804,7 @@ arg_0		= word ptr  4
 		mov	si, [bp+arg_0]
 		cmp	byte ptr [si+1Fh], 0
 		jz	short loc_DEB2
-		cmp	byte ptr [si+1Fh], 0FFh
+		cmp	byte ptr [si+1Fh], -1
 		jz	short loc_DF12
 		push	si
 		call	sub_C248
@@ -8155,12 +8155,12 @@ loc_E13C:
 		sar	dx, 3
 		mov	di, [bp+arg_0]
 		add	di, cx
-		mov	ch, 0FFh
+		mov	ch, 11111111b
 		shr	ch, cl
 		mov	bx, di
 		cmp	bx, 8
 		jg	short loc_E163
-		mov	bh, 0FFh
+		mov	bh, 11111111b
 		mov	cl, bl
 		shr	bh, cl
 		xor	ch, bh
@@ -8213,11 +8213,11 @@ loc_E1B3:
 		mov	ch, 0
 		add	bx, cx
 		sub	di, 8
-		mov	ch, 0FFh
+		mov	ch, 11111111b
 		cmp	di, 8
 		jnb	short loc_E1CB
 		mov	cx, di
-		mov	ch, 0FFh
+		mov	ch, 11111111b
 		shr	ch, cl
 		not	ch
 
@@ -8572,7 +8572,7 @@ loc_E4A2:
 		movzx	eax, byte_23DF9
 		imul	eax, 100000
 		add	score_23DF0, eax
-		mov	byte_220DC, 0FFh
+		mov	byte_220DC, -1
 
 loc_E55E:
 		mov	eax, score_23DF0
@@ -9359,7 +9359,7 @@ loc_F32F:
 ; ---------------------------------------------------------------------------
 
 loc_F34E:
-		mov	al, 0FFh
+		mov	al, -1
 
 loc_F350:
 		pop	di
@@ -9436,7 +9436,7 @@ loc_F3D6:
 		cmp	word_1F340, 1A00h
 		jl	short loc_F400
 		mov	byte_1F34F, 0
-		mov	byte_1DB9E, 0FFh
+		mov	byte_1DB9E, -1
 		mov	word_21434, 1400h
 
 loc_F400:
@@ -9459,7 +9459,7 @@ sub_F402	proc near
 		mov	bx, ax
 		cmp	byte ptr [bx+2D54h], 5
 		jnz	loc_F4AE
-		cmp	byte_1DB9E, 0FFh
+		cmp	byte_1DB9E, -1
 		jnz	short loc_F481
 		mov	si, 1DFEh
 		cmp	_pid_current, 1
@@ -9499,9 +9499,9 @@ loc_F42B:
 ; ---------------------------------------------------------------------------
 
 loc_F481:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_F4AE
-		mov	byte_1F34F, 0FFh
+		mov	byte_1F34F, -1
 		mov	word_1F3B0, 0
 		mov	al, 1
 		sub	al, _pid_current
@@ -9538,9 +9538,9 @@ sub_F4B4	proc far
 		mov	[bp+@@pid_other], al
 		cmp	word_1F34A, 0
 		jg	short locret_F510
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short locret_F510
-		mov	byte_1F34F, 0FFh
+		mov	byte_1F34F, -1
 		mov	word_1F3B0, 0
 		push	word ptr [bp+@@pid_other]
 		call	sub_A3A8
@@ -9652,7 +9652,7 @@ sub_F58C	proc near
 		mov	byte_1F34F, al
 		cmp	byte_1F34F, 0
 		jnz	short loc_F5AD
-		mov	byte_1DB9E, 0FFh
+		mov	byte_1DB9E, -1
 
 loc_F5AD:
 		pop	bp
@@ -10293,7 +10293,7 @@ loc_FB1E:
 ; ---------------------------------------------------------------------------
 
 loc_FB35:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_FB41
 		call	sub_F9A6
 		leave
@@ -11090,7 +11090,7 @@ loc_10299:
 ; ---------------------------------------------------------------------------
 
 loc_102B7:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_102C3
 		call	sub_10053
 		leave
@@ -12092,7 +12092,7 @@ loc_10BE1:
 ; ---------------------------------------------------------------------------
 
 loc_10BED:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_10BF9
 		call	sub_108CA
 		leave
@@ -12950,7 +12950,7 @@ reimu_113A9	proc far
 ; ---------------------------------------------------------------------------
 
 loc_113D1:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_113DD
 		call	sub_111A3
 		pop	bp
@@ -13728,7 +13728,7 @@ loc_11A37:
 ; ---------------------------------------------------------------------------
 
 loc_11A5C:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_11A68
 		call	sub_11885
 		leave
@@ -14535,7 +14535,7 @@ loc_12172:
 ; ---------------------------------------------------------------------------
 
 loc_1218C:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_12198
 		call	sub_120A0
 		pop	bp
@@ -15680,7 +15680,7 @@ loc_12BCB:
 ; ---------------------------------------------------------------------------
 
 loc_12BD7:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_12BE3
 		call	sub_12A10
 		pop	bp
@@ -15689,7 +15689,7 @@ loc_12BD7:
 
 loc_12BE3:
 		call	sub_F58C
-		cmp	byte_1DB9E, 0FFh
+		cmp	byte_1DB9E, -1
 		jnz	short loc_12BF9
 		mov	al, 1
 		sub	al, _pid_current
@@ -16044,20 +16044,20 @@ loc_12F17:
 		sub	dx, ax
 		push	dx
 		call	sub_CE0C
-		mov	byte_23DE6, 0C0h
+		mov	byte_23DE6, -40h
 		push	3
 		call	randring_far_next16_and
 		mov	byte_23DE7, al
 		cmp	byte_23DE7, 0
 		jnz	short loc_12F5A
-		mov	al, 0FDh
+		mov	al, -3
 		jmp	short loc_12F72
 ; ---------------------------------------------------------------------------
 
 loc_12F5A:
 		cmp	byte_23DE7, 1
 		jnz	short loc_12F65
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_12F72
 ; ---------------------------------------------------------------------------
 
@@ -16508,7 +16508,7 @@ loc_13330:
 ; ---------------------------------------------------------------------------
 
 loc_1333C:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_13348
 		call	sub_13174
 		pop	bp
@@ -16685,7 +16685,7 @@ var_1		= byte ptr -1
 
 		enter	2, 0
 		push	si
-		cmp	byte_1F358, 0F8h
+		cmp	byte_1F358, -8
 		jl	short loc_134C1
 		test	byte ptr word_1F3B0, 7
 		jnz	short loc_134C1
@@ -16811,7 +16811,7 @@ var_1		= byte ptr -1
 		jnz	short loc_135CD
 		cmp	byte_1F358, 2
 		jle	short loc_135C4
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_135C6
 ; ---------------------------------------------------------------------------
 
@@ -17262,7 +17262,7 @@ loc_139BD:
 ; ---------------------------------------------------------------------------
 
 loc_139C9:
-		cmp	byte_1F34F, 0FFh
+		cmp	byte_1F34F, -1
 		jz	short loc_139D5
 		call	sub_137CF
 		pop	bp
@@ -17357,13 +17357,13 @@ loc_13AE3:
 loc_13AFC:
 		add	bx, 1234h
 		mov	ax, cx
-		mov	ah, 0FFh
+		mov	ah, 11111111b
 
 loc_13B04:
 		shr	ah, 4
 		cmp	dl, 8
 		jge	short loc_13B14
-		mov	ch, 0FFh
+		mov	ch, 11111111b
 		mov	cl, dl
 		shr	ch, cl
 		xor	ah, ch
@@ -17387,7 +17387,7 @@ loc_13B1B:
 loc_13B2C:
 		add	cx, 1234h
 		add	bx, cx
-		mov	ah, 0FFh
+		mov	ah, 11111111b
 		cmp	dl, 8
 		jge	short loc_13B14
 		mov	cl, dl
@@ -17466,7 +17466,7 @@ sub_13B9A	proc far
 loc_13BAA:
 		add	bx, 4BA0h
 		mov	word ptr cs:loc_13BE9+1, bx
-		mov	al, 0FFh
+		mov	al, 11111111b
 		mov	cx, word_220F2
 		shr	al, cl
 		not	al
@@ -22625,7 +22625,7 @@ arg_2		= word ptr  6
 		inc	byte_1F39E
 
 loc_16656:
-		cmp	byte_1DB9E, 0FFh
+		cmp	byte_1DB9E, -1
 		jnz	short loc_1666D
 		mov	al, cl
 		mov	ah, 0
@@ -23011,14 +23011,14 @@ arg_0		= byte ptr  6
 		push	bp
 		mov	bp, sp
 		push	si
-		mov	dl, 0FFh
+		mov	dl, -1
 		mov	al, [bp+arg_0]
 		mov	ah, 0
 		add	ax, ax
 		mov	bx, ax
 		cmp	word ptr [bx+1DCAh], 0
 		jz	short loc_169AD
-		mov	byte_20E48, 0FEh
+		mov	byte_20E48, -2
 		mov	ax, word_1F326
 		mov	word_2142E, ax
 		mov	ax, word_1F328
@@ -23062,11 +23062,11 @@ loc_169EF:
 		jl	short loc_169B4
 
 loc_169F4:
-		cmp	dl, 0FFh
+		cmp	dl, -1
 		jnz	short loc_16A0C
 		mov	word_2142E, 900h
 		mov	word_21430, 12C0h
-		mov	byte_20E48, 0FFh
+		mov	byte_20E48, -1
 		jmp	short loc_16A50
 ; ---------------------------------------------------------------------------
 
@@ -26199,7 +26199,7 @@ loc_182D6:
 		mov	bx, ax
 		mov	al, [bx+4B3Eh]
 		add	al, byte_2203A
-		add	al, 0FFh
+		add	al, -1
 		mov	dl, [bp+@@pid]
 		mov	dh, 0
 		shl	dx, 4
@@ -28131,7 +28131,7 @@ arg_4		= word ptr  0Ah
 		call	randring_far_next16_and
 		or	ax, ax
 		jnz	short loc_19423
-		mov	al, 0FFh
+		mov	al, -1
 		jmp	short loc_19425
 ; ---------------------------------------------------------------------------
 
@@ -33029,7 +33029,7 @@ loc_1B855:
 loc_1B871:
 		mov	bx, word_1F868
 		mov	al, [bx]
-		add	al, 0FFh
+		add	al, -1
 		mov	[bx], al
 		cmp	al, 1
 		jnz	short loc_1B886
diff --git a/th03_mainl.asm b/th03_mainl.asm
index d47ccc4b..81bee12d 100644
--- a/th03_mainl.asm
+++ b/th03_mainl.asm
@@ -2447,7 +2447,7 @@ loc_ABFE:
 ; ---------------------------------------------------------------------------
 
 loc_AC1A:
-		mov	al, 0FFh	; jumptable 0000A67C case 36
+		mov	al, -1	; jumptable 0000A67C case 36
 		jmp	short loc_AC20
 ; ---------------------------------------------------------------------------
 
@@ -2540,7 +2540,7 @@ loc_ACBB:
 		inc	word ptr _cutscene_script
 		push	word ptr [bp+var_1]
 		call	sub_A64D
-		cmp	al, 0FFh
+		cmp	al, -1
 		jnz	short loc_ACA3
 		jmp	loc_ADA0
 ; ---------------------------------------------------------------------------
diff --git a/th04_main.asm b/th04_main.asm
index 0fe0e165..c52bdfe4 100644
--- a/th04_main.asm
+++ b/th04_main.asm
@@ -3233,7 +3233,7 @@ loc_D350:
 		jnz	short loc_D38A
 		push	2000F0h
 		call	main_01:sub_D04E
-		cmp	[bp+var_2], 0FFh
+		cmp	[bp+var_2], (-1 and 255)
 		jz	loc_D528	; default
 		add	[bp+var_2], 2
 		push	2000F0h
@@ -3243,7 +3243,7 @@ loc_D350:
 loc_D38A:
 		push	1200070h
 		call	main_01:sub_D04E
-		cmp	[bp+var_2], 0FFh
+		cmp	[bp+var_2], (-1 and 255)
 		jz	loc_D528	; default
 		add	[bp+var_2], 8
 		push	1200070h
@@ -3422,7 +3422,7 @@ loc_D51D:
 		call	input_wait_for_change pascal, 0		; jumptable 0000D1EC case 36
 
 loc_D524:
-		mov	al, 0FFh	; jumptable 0000D1EC case 35
+		mov	al, -1	; jumptable 0000D1EC case 35
 		jmp	short loc_D52A
 ; ---------------------------------------------------------------------------
 
@@ -3492,7 +3492,7 @@ loc_D57A:
 		inc	word ptr dword_255CC
 		push	word ptr [bp+var_1]
 		call	main_01:sub_D1BC
-		cmp	al, 0FFh
+		cmp	al, -1
 		jnz	short loc_D57A
 		jmp	loc_D6E4
 ; ---------------------------------------------------------------------------
@@ -3579,7 +3579,7 @@ loc_D63F:
 		inc	word ptr dword_255CC
 		push	word ptr [bp+var_1]
 		call	main_01:sub_D1BC
-		cmp	al, 0FFh
+		cmp	al, -1
 		jnz	short loc_D63F
 		jmp	loc_D57A
 ; ---------------------------------------------------------------------------
@@ -11157,7 +11157,7 @@ sub_12076	proc near
 loc_12086:
 		mov	dx, word_2323A
 		mov	di, bx
-		and	di, 0FFh
+		and	di, 255
 		add	di, word_2323C
 		jmp	short loc_120AF
 ; ---------------------------------------------------------------------------
@@ -11165,14 +11165,14 @@ loc_12086:
 loc_12096:
 		mov	dx, GRAM_400 + (PLAYFIELD_TOP * ROW_SIZE) shr 4
 		mov	di, bx
-		and	di, 0FFh
+		and	di, 255
 		add	di, word_2323E
 		jmp	short loc_120AF
 ; ---------------------------------------------------------------------------
 
 loc_120A5:
 		mov	di, bx
-		and	di, 0FFh
+		and	di, 255
 		add	di, 9B0h
 
 loc_120AF:
@@ -11779,7 +11779,7 @@ loc_12522:
 		cmp	_boss_phase, 2
 		jbe	short loc_12567
 		inc	byte_2CDD1
-		cmp	byte_2CDD1, 0FEh
+		cmp	byte_2CDD1, 254
 		jb	loc_127EC
 		mov	word_2CF28, 78h	; 'x'
 		mov	byte_2CDD0, 4
@@ -11797,13 +11797,13 @@ loc_12548:
 loc_12554:
 		cmp	di, 38h	; '8'
 		jl	short loc_12548
-		mov	byte_2CDD1, 0FFh
+		mov	byte_2CDD1, 255
 		mov	word_2CF2A, 40h
 		jmp	loc_127EC
 ; ---------------------------------------------------------------------------
 
 loc_12567:
-		cmp	byte_2CDD1, 0FFh
+		cmp	byte_2CDD1, 255
 		jnz	loc_127EC
 		inc	word_2CF28
 		inc	byte_2CDD0
@@ -11835,7 +11835,7 @@ loc_125A5:
 		cmp	_boss_phase, 4
 		jbe	short loc_125F6
 		inc	byte_2CDD1
-		cmp	byte_2CDD1, 0FEh
+		cmp	byte_2CDD1, 254
 		jb	loc_127EC
 		mov	word_2CF28, 78h	; 'x'
 		mov	byte_2CDD0, 6
@@ -11865,7 +11865,7 @@ loc_125E8:
 ; ---------------------------------------------------------------------------
 
 loc_125F6:
-		cmp	byte_2CDD1, 0FFh
+		cmp	byte_2CDD1, 255
 		jnz	loc_127EC
 		cmp	byte_2CDD0, 4
 		jnz	loc_127AB
@@ -11884,7 +11884,7 @@ loc_1260B:
 
 loc_12627:
 		inc	byte_2CDD1
-		cmp	byte_2CDD1, 0FEh
+		cmp	byte_2CDD1, 254
 		jb	loc_127EC
 		mov	word_2CF28, 78h	; 'x'
 		cmp	byte_2CDD0, 0Ah
@@ -11925,7 +11925,7 @@ loc_12674:
 ; ---------------------------------------------------------------------------
 
 loc_1267C:
-		cmp	byte_2CDD1, 0FFh
+		cmp	byte_2CDD1, 255
 		jnz	loc_127EC
 		test	byte_2CDD0, 1
 		jz	loc_127B1
@@ -11942,7 +11942,7 @@ loc_12691:
 
 loc_126A6:
 		inc	byte_2CDD1
-		cmp	byte_2CDD1, 0FEh
+		cmp	byte_2CDD1, 254
 		jb	loc_127EC
 		mov	word_2CF28, 78h	; 'x'
 		cmp	byte_2CDD0, 0Ch
@@ -11991,12 +11991,12 @@ loc_126FF:
 		mov	word_2CF2A, 40h
 
 loc_12705:
-		mov	byte_2CDD1, 0FFh
+		mov	byte_2CDD1, 255
 		jmp	loc_127EC
 ; ---------------------------------------------------------------------------
 
 loc_1270D:
-		cmp	byte_2CDD1, 0FFh
+		cmp	byte_2CDD1, 255
 		jnz	loc_127EC
 		test	byte_2CDD0, 1
 		jz	loc_127B1
@@ -12032,11 +12032,11 @@ loc_12743:
 		cmp	_boss_phase, 0Fh
 		jb	short loc_1279D
 		inc	byte_2CDD1
-		cmp	byte_2CDD1, 0FEh
+		cmp	byte_2CDD1, 254
 		jb	loc_127EC
 		mov	word_2CF28, 7Ch	; '|'
 		mov	byte_2CDD0, 10h
-		mov	byte_2CDD1, 0FFh
+		mov	byte_2CDD1, 255
 		mov	si, 0BA92h
 		xor	di, di
 		jmp	short loc_12790
@@ -12062,7 +12062,7 @@ loc_12790:
 ; ---------------------------------------------------------------------------
 
 loc_1279D:
-		cmp	byte_2CDD1, 0FFh
+		cmp	byte_2CDD1, 255
 		jnz	short loc_127EC
 		test	byte_2CDD0, 1
 		jz	short loc_127B1
@@ -12082,7 +12082,7 @@ loc_127B7:
 		jb	short loc_127EC
 		mov	word_2CF28, 7Dh	; '}'
 		mov	byte_2CDD0, 11h
-		mov	byte_2CDD1, 0FFh
+		mov	byte_2CDD1, 255
 		mov	si, 0BA92h
 		xor	di, di
 		jmp	short loc_127E1
@@ -12520,7 +12520,7 @@ loc_12BCF:
 loc_12BDC:
 		cmp	[bp+var_2], 9
 		jnz	short loc_12BEA
-		mov	byte_2CFF2, 0FFh
+		mov	byte_2CFF2, -1
 		jmp	loc_12CB2
 ; ---------------------------------------------------------------------------
 
@@ -13464,7 +13464,7 @@ loc_13FCC:
 		mov	_bullet_template.BT_angle, al
 		mov	_bullet_template.speed, (2 shl 4)
 		mov	_bullet_template.pattern, BP_SINGLE
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		call	_bullet_template_tune
 		call	fp_2D002
 		mov	al, 80h
@@ -13769,7 +13769,7 @@ loc_14339:
 loc_1436F:
 		cmp	_midboss_phase_frame, 32
 		jl	short loc_14381
-		mov	byte_25598, 0FFh
+		mov	byte_25598, -1
 		mov	_midboss_phase_frame, 0
 
 loc_14381:
@@ -13787,7 +13787,7 @@ sub_14383	proc near
 		mov	bp, sp
 		cmp	_midboss_phase_frame, 32
 		jl	short loc_143C5
-		mov	byte_25598, 0FFh
+		mov	byte_25598, -1
 		mov	_midboss_phase_frame, 0
 		mov	_bullet_template.spawn_type, BST_BULLET16_CLOUD_BACKWARDS
 		mov	_bullet_template.patnum, PAT_BULLET16_N_BALL_BLUE
@@ -13839,7 +13839,7 @@ loc_143D6:
 loc_14411:
 		cmp	_midboss_phase_frame, 32
 		jl	short loc_14423
-		mov	byte_25598, 0FFh
+		mov	byte_25598, -1
 		mov	_midboss_phase_frame, 0
 
 loc_14423:
@@ -13884,7 +13884,7 @@ loc_14435:
 loc_14477:
 		cmp	_midboss_phase_frame, 32
 		jl	short loc_14489
-		mov	byte_25598, 0FFh
+		mov	byte_25598, -1
 		mov	_midboss_phase_frame, 0
 
 loc_14489:
@@ -14093,7 +14093,7 @@ midboss3_update	endp
 ; ---------------------------------------------------------------------------
 		db    0
 word_1469B	dw	0,     1,     2,     3
-		dw   0FFh		; value	table for switch statement
+		dw   (-1 and 255)		; value	table for switch statement
 		dw offset loc_1453A	; jump table for switch	statement
 		dw offset loc_14540
 		dw offset loc_14546
@@ -14603,7 +14603,7 @@ loc_14B63:
 		cmp	si, 64
 		jl	short loc_14B73
 		mov	_midboss_phase_frame, 0
-		mov	byte_255B2, 0FFh
+		mov	byte_255B2, -1
 
 loc_14B73:
 		pop	si
@@ -14647,7 +14647,7 @@ loc_14BBA:
 		cmp	si, 20h	; ' '
 		jl	short loc_14BCA
 		mov	_midboss_phase_frame, 0
-		mov	byte_255B2, 0FFh
+		mov	byte_255B2, -1
 
 loc_14BCA:
 		pop	si
@@ -14700,7 +14700,7 @@ loc_14C32:
 		cmp	si, 20h	; ' '
 		jl	short loc_14C42
 		mov	_midboss_phase_frame, 0
-		mov	byte_255B2, 0FFh
+		mov	byte_255B2, -1
 
 loc_14C42:
 		pop	si
@@ -14758,7 +14758,7 @@ loc_14C6B:
 		mov	_bullet_template.BT_angle, al
 		mov	_bullet_template.patnum, PAT_BULLET16_D_BLUE
 		mov	_bullet_template.pattern, BP_SINGLE
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 
 loc_14CCC:
 		mov	ax, si
@@ -14777,7 +14777,7 @@ loc_14CEA:
 		cmp	si, 40h
 		jl	short loc_14CFA
 		mov	_midboss_phase_frame, 0
-		mov	byte_255B2, 0FFh
+		mov	byte_255B2, -1
 
 loc_14CFA:
 		pop	si
@@ -15091,7 +15091,7 @@ loc_15000:
 
 loc_1501A:
 		mov	_midboss_phase_frame, 0
-		mov	byte_255C6, 0FFh
+		mov	byte_255C6, -1
 
 loc_15025:
 		pop	bp
@@ -15203,7 +15203,7 @@ loc_150F6:
 
 loc_15110:
 		mov	_midboss_phase_frame, 0
-		mov	byte_255C6, 0FFh
+		mov	byte_255C6, -1
 
 locret_1511B:
 		leave
@@ -15301,7 +15301,7 @@ loc_151DA:
 
 loc_151F4:
 		mov	_midboss_phase_frame, 0
-		mov	byte_255C6, 0FFh
+		mov	byte_255C6, -1
 
 loc_151FF:
 		pop	si
@@ -15380,7 +15380,7 @@ loc_1528D:
 
 loc_152A7:
 		mov	_midboss_phase_frame, 0
-		mov	byte_255C6, 0FFh
+		mov	byte_255C6, -1
 
 loc_152B2:
 		pop	bp
@@ -15633,7 +15633,7 @@ midboss4_update	endp
 ; ---------------------------------------------------------------------------
 		db 0
 word_1553B	dw	0,     1,     2,     3
-		dw   0FFh		; value	table for switch statement
+		dw   (-1 and 255)		; value	table for switch statement
 		dw offset loc_1535C	; jump table for switch	statement
 		dw offset loc_15361
 		dw offset loc_15366
@@ -16952,7 +16952,7 @@ loc_16057:
 loc_1606B:
 		cmp	_boss_phase_frame, 140
 		jnz	short loc_1607E
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1607E:
@@ -17077,7 +17077,7 @@ loc_16187:
 loc_161C2:
 		cmp	_boss_phase_frame, 288
 		jnz	short loc_161D5
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_161D5:
@@ -17197,7 +17197,7 @@ sub_162A3	proc near
 loc_162D7:
 		cmp	_boss_phase_frame, 170
 		jnz	short loc_162EA
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_162EA:
@@ -17251,7 +17251,7 @@ loc_1632F:
 loc_16353:
 		cmp	_boss_phase_frame, 128
 		jnz	short loc_16366
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_16366:
@@ -17454,7 +17454,7 @@ sub_1653D	proc near
 		mov	_circles_color, 0Fh
 		mov	_boss_angle, 16
 		mov	byte_2D02D, 10h
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		pop	bp
 		retn
 ; ---------------------------------------------------------------------------
@@ -18511,7 +18511,7 @@ loc_16E84:
 		cmp	_bullet_template.BT_angle, 0
 		jnz	short locret_16E9B
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 locret_16E9B:
@@ -18579,7 +18579,7 @@ loc_16EF1:
 
 loc_16EFE:
 		mov	_boss_phase_frame, 0	; jumptable 00016EBF case 96
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 locret_16F0E:
@@ -18733,7 +18733,7 @@ loc_17048:
 		cmp	di, 4
 		jl	short loc_1703C
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 loc_1705D:
@@ -18873,7 +18873,7 @@ loc_17164:
 		cmp	di, 4
 		jl	short loc_17154
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 loc_17179:
@@ -19059,7 +19059,7 @@ loc_1730D:
 
 loc_17318:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 		jmp	short loc_17331
 ; ---------------------------------------------------------------------------
@@ -19160,7 +19160,7 @@ loc_173D3:
 		mov	_bullet_template.spawn_type, BST_BULLET16_CLOUD_FORWARDS
 		mov	_bullet_template.patnum, PAT_BULLET16_N_BALL_RED
 		mov	_bullet_template.pattern, BP_SINGLE_AIMED
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		call	_bullet_template_tune
 		xor	si, si
 		jmp	short loc_1746F
@@ -19216,7 +19216,7 @@ loc_1746F:
 
 loc_1747D:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 loc_1748D:
@@ -19438,7 +19438,7 @@ loc_17683:
 
 loc_1768B:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 loc_1769B:
@@ -19464,7 +19464,7 @@ var_1		= byte ptr -1
 		mov	_bullet_template.spawn_type, BST_BULLET16
 		mov	_bullet_template.patnum, PAT_BULLET16_N_STAR
 		mov	_bullet_template.pattern, BP_SINGLE
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		mov	_bullet_template.BT_angle, -40h
 		mov	_bullet_template.speed, (6 shl 4)
 		mov	fp_25676, offset sub_17061
@@ -19569,7 +19569,7 @@ loc_177F9:
 
 loc_17801:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 locret_17811:
@@ -19605,7 +19605,7 @@ var_1		= byte ptr -1
 ; ---------------------------------------------------------------------------
 
 loc_17848:
-		mov	al, 0FFh
+		mov	al, -1
 
 loc_1784A:
 		mov	byte_2D02D, al
@@ -19631,7 +19631,7 @@ loc_17874:
 		cmp	_boss_phase_frame, 128
 		jl	short locret_1788C
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 locret_1788C:
@@ -19754,7 +19754,7 @@ loc_1795F:
 
 loc_179A8:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_sprite, 129
 
 loc_179B8:
@@ -20981,7 +20981,7 @@ loc_1836D:
 
 loc_1837D:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_18388:
 		pop	bp
@@ -21067,7 +21067,7 @@ loc_1841E:
 
 loc_18451:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 locret_1845C:
 		leave
@@ -21108,7 +21108,7 @@ loc_18473:
 
 loc_1849F:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		pop	bp
 		retn
 sub_1845E	endp
@@ -21175,7 +21175,7 @@ loc_184D9:
 
 loc_18549:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_18554:
 		pop	bp
@@ -21239,7 +21239,7 @@ loc_18580:
 
 loc_185D7:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_185E2:
 		pop	bp
@@ -21514,7 +21514,7 @@ loc_18844:
 loc_18856:
 		cmp	_mugetsu_phase2_mode, 32 ; default
 		jb	short loc_1886E
-		cmp	_boss_mode, 0FFh
+		cmp	_boss_mode, -1
 		jz	short loc_1886E
 		cmp	_boss_phase_frame, 24
 		jle	short loc_1886E
@@ -22527,7 +22527,7 @@ loc_190DE:
 		call	randring2_next16_and pascal, 0Fh
 		add	al, (2 shl 4)
 		mov	_bullet_template.speed, al
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		call	_bullet_template_tune
 		call	fp_2D002
 
@@ -23213,7 +23213,7 @@ loc_19751:
 		mov	_bullet_template.pattern, BP_SPREAD
 		mov	_bullet_template.count, 3
 		mov	_bullet_template.BT_delta.spread_angle, 0Ch
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		mov	al, _boss_angle
 		add	al, -20h
 		mov	_bullet_template.BT_angle, al
@@ -23622,7 +23622,7 @@ loc_19B56:
 		mov	_boss_phase_frame, 0
 		call	snd_se_play pascal, 13
 		mov	byte_2D02D, 0
-		mov	byte_2D02C, 0FFh
+		mov	byte_2D02C, -1
 		mov	fp_255AC, offset orange_bg_render
 		mov	byte_2CDCA, 0
 		jmp	short loc_19C02
@@ -25183,7 +25183,7 @@ loc_1AB86:
 
 loc_1ABD8:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		pop	bp
 		retn
 sub_1AB5D	endp
@@ -25279,7 +25279,7 @@ loc_1ACA5:
 
 loc_1ACBF:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		leave
 		retn
 sub_1ABE5	endp
@@ -25340,7 +25340,7 @@ loc_1AD58:
 		cmp	_boss_phase_frame, 80
 		jle	short loc_1AD6A
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1AD6A:
 		call	sub_1A907
@@ -25394,7 +25394,7 @@ loc_1ADBA:
 		or	al, al
 		jz	short loc_1ADCC
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1ADCC:
 		call	sub_1A9CA
@@ -25543,7 +25543,7 @@ loc_1AF47:
 		or	al, al
 		jz	short loc_1AF59
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1AF59:
 		call	sub_1AA45
@@ -25662,7 +25662,7 @@ loc_1B082:
 		or	al, al
 		jz	short loc_1B094
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1B094:
 		call	sub_1AA45
@@ -25797,7 +25797,7 @@ loc_1B19D:
 
 loc_1B1A4:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1B1AF:
 		pop	bp
@@ -25851,7 +25851,7 @@ loc_1B213:
 		cmp	_boss_phase_frame, 144
 		jnz	short loc_1B229
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1B229:
 		pop	bp
@@ -25897,7 +25897,7 @@ loc_1B26D:
 		cmp	_boss_phase_frame, 144
 		jnz	short loc_1B280
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1B280:
 		pop	bp
@@ -26044,7 +26044,7 @@ loc_1B3CB:
 		or	al, al
 		jz	short loc_1B3DD
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1B3DD:
 		call	sub_1AA45
@@ -26231,7 +26231,7 @@ loc_1B5CB:
 		mov	ah, 0
 		or	ax, ax
 		jz	short loc_1B5DB
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_1B5E0
 		jmp	short loc_1B600
 ; ---------------------------------------------------------------------------
@@ -26257,7 +26257,7 @@ loc_1B5E0:
 loc_1B600:
 		cmp	_boss_sprite, 0
 		jz	loc_1B787
-		cmp	_boss_mode, 0FFh
+		cmp	_boss_mode, -1
 		jz	loc_1B787
 		call	sub_1E64E
 		or	al, al
@@ -26313,12 +26313,12 @@ loc_1B694:
 		jz	loc_1B8EA
 		inc	_boss_phase
 		mov	_boss_mode_change, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 		mov	_yuuka6_anim_frame, 0
 		mov	_yuuka6_sprite_state, Y6SS_PARASOL_BACK_CLOSED
 		mov	byte_25A1B, 1
-		mov	byte_25A02, 0FFh
+		mov	byte_25A02, -1
 		jmp	loc_1B8EA
 ; ---------------------------------------------------------------------------
 
@@ -26704,7 +26704,7 @@ loc_1BA19:
 		jb	short loc_1BA33
 		cmp	[bp+var_1], 0F0h
 		ja	short loc_1BA33
-		mov	byte_25A38, 0FFh
+		mov	byte_25A38, -1
 
 loc_1BA2A:
 		mov	al, _stage_frame_mod2
@@ -27044,7 +27044,7 @@ loc_1BD30:
 		jle	short loc_1BD49
 		cmp	byte_25A26, 0
 		jnz	short loc_1BD49
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1BD49:
@@ -27087,7 +27087,7 @@ loc_1BD64:
 loc_1BDA0:
 		cmp	byte_25A26, 0
 		jnz	short loc_1BDB2
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1BDB2:
@@ -27189,7 +27189,7 @@ word_1BE33	dw 1
 sub_1BE43	proc near
 		push	bp
 		mov	bp, sp
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 		mov	_bullet_template.BT_angle, 0
 		mov	_bullet_template.spawn_type, BST_BULLET16_CLOUD_BACKWARDS
@@ -27334,7 +27334,7 @@ loc_1BF66:
 loc_1BF97:
 		cmp	byte_25A26, 0
 		jnz	short loc_1BFA9
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1BFA9:
@@ -27458,7 +27458,7 @@ loc_1C07C:
 loc_1C0AB:
 		cmp	byte_25A26, 0
 		jnz	short loc_1C0BD
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1C0BD:
@@ -27587,7 +27587,7 @@ loc_1C19C:
 loc_1C1BB:
 		cmp	byte_25A26, 0
 		jnz	short loc_1C1CD
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1C1CD:
@@ -27693,7 +27693,7 @@ loc_1C2AD:
 loc_1C2D1:
 		cmp	byte_25A26, 0
 		jnz	short loc_1C2E3
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 
 loc_1C2E3:
@@ -27739,7 +27739,7 @@ loc_1C32D:
 		mov	ah, 0
 		or	ax, ax
 		jz	short loc_1C343
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_1C348
 		jmp	short loc_1C39E
 ; ---------------------------------------------------------------------------
@@ -27938,7 +27938,7 @@ loc_1C4EB:
 		mov	al, byte_25A24
 		mov	ah, 0
 		call	boss_explode_small pascal, ax
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		inc	byte_25A24
 		mov	al, byte_25A24
 		mov	ah, 0
@@ -28052,7 +28052,7 @@ loc_1C600:
 		mov	al, byte_25A24
 		mov	ah, 0
 		call	boss_explode_small pascal, ax
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	_boss_phase_frame, 0
 		inc	byte_25A24
 		jmp	short loc_1C67A
@@ -31964,7 +31964,7 @@ loc_1EDA3:
 		jl	short locret_1EDBA
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 locret_1EDBA:
 		leave
@@ -32005,7 +32005,7 @@ loc_1EE01:
 		jl	short locret_1EE1F
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 locret_1EE1F:
 		leave
@@ -32039,7 +32039,7 @@ loc_1EE57:
 		cmp	_boss_phase_frame, 96
 		jl	short loc_1EE71
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	al, byte_2D057
 		neg	al
 		mov	byte_2D057, al
@@ -32141,7 +32141,7 @@ loc_1EF6C:
 		jl	short loc_1EF84
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1EF84:
 		pop	si
@@ -32212,7 +32212,7 @@ loc_1F034:
 		jl	short locret_1F04C
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 locret_1F04C:
 		leave
@@ -32294,7 +32294,7 @@ loc_1F0F8:
 loc_1F0FF:
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 locret_1F10F:
 		leave
@@ -32340,7 +32340,7 @@ loc_1F15F:
 		cmp	_boss_phase_frame, 180
 		jl	short loc_1F17A
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	al, byte_2D057
 		neg	al
 		mov	byte_2D057, al
@@ -32366,7 +32366,7 @@ sub_1F17C	proc near
 		mov	_bullet_template.spawn_type, BST_BULLET16_CLOUD_FORWARDS
 		mov	_bullet_template.patnum, PAT_BULLET16_N_BALL_BLUE
 		mov	_bullet_template.BT_angle, -40h
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		mov	_bullet_template.BT_delta.stack_speed, 8
 
 loc_1F1AA:
@@ -32436,7 +32436,7 @@ var_1		= byte ptr -1
 		mov	_bullet_template.spawn_type, BST_BULLET16_CLOUD_FORWARDS
 		mov	_bullet_template.patnum, PAT_BULLET16_N_BALL_BLUE
 		mov	_bullet_template.BT_angle, -40h
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		mov	_bullet_template.BT_delta.spread_angle, 8
 		cmp	byte_237F6, 78h	; 'x'
 		jz	short loc_1F25E
@@ -32491,7 +32491,7 @@ loc_1F2D9:
 		jl	short locret_1F2F1
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 locret_1F2F1:
 		leave
@@ -32518,7 +32518,7 @@ var_1		= byte ptr -1
 		mov	al, byte_2D024
 		mov	_bullet_template.count, al
 		mov	_bullet_template.BT_delta.stack_speed, 12
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		mov	_bullet_template.BT_angle, 0
 		mov	_bullet_template.patnum, PAT_BULLET16_N_BALL_BLUE
 
@@ -32553,7 +32553,7 @@ loc_1F35D:
 		jl	short loc_1F375
 		mov	_boss_sprite, 128
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1F375:
 		pop	si
@@ -32654,7 +32654,7 @@ loc_1F44D:
 		jz	short loc_1F462
 		cmp	ax, 1
 		jz	short loc_1F467
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_1F46C
 		jmp	short loc_1F46F
 ; ---------------------------------------------------------------------------
@@ -32844,7 +32844,7 @@ loc_1F5E1:
 		jz	short loc_1F5F6
 		cmp	ax, 1
 		jz	short loc_1F5FB
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_1F600
 		jmp	short loc_1F603
 ; ---------------------------------------------------------------------------
@@ -32942,7 +32942,7 @@ loc_1F6B8:
 		jz	short loc_1F6CD
 		cmp	ax, 1
 		jz	short loc_1F6D2
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_1F6D7
 		jmp	short loc_1F6E9
 ; ---------------------------------------------------------------------------
@@ -32988,7 +32988,7 @@ loc_1F718:
 		jz	short loc_1F72D
 		cmp	ax, 1
 		jz	short loc_1F732
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_1F737
 		jmp	short loc_1F73A
 ; ---------------------------------------------------------------------------
@@ -33487,7 +33487,7 @@ loc_1FABE:
 
 loc_1FAEA:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		pop	bp
 		retn
 sub_1FAAA	endp
@@ -33554,7 +33554,7 @@ loc_1FB36:
 
 loc_1FB79:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1FB84:
 		pop	bp
@@ -33628,7 +33628,7 @@ loc_1FBAD:
 
 loc_1FC39:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1FC44:
 		pop	bp
@@ -33716,7 +33716,7 @@ loc_1FCE0:
 
 loc_1FD23:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1FD2E:
 		pop	bp
@@ -33743,7 +33743,7 @@ sub_1FD30	proc near
 loc_1FD49:
 		mov	_bullet_template.patnum, PAT_BULLET16_N_HEART_BALL_RED
 		mov	_bullet_template.pattern, BP_SPREAD_AIMED
-		mov	_bullet_template.BT_special_motion, 0FFh
+		mov	_bullet_template.BT_special_motion, -1
 		mov	_bullet_template.BT_delta.spread_angle, 10h
 		mov	_bullet_template.BT_angle, 0
 		mov	_bullet_template.count, 2
@@ -33802,7 +33802,7 @@ loc_1FDCD:
 
 loc_1FDE6:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1FDF1:
 		pop	si
@@ -33865,7 +33865,7 @@ loc_1FE45:
 
 loc_1FE5D:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1FE68:
 		pop	bp
@@ -33922,7 +33922,7 @@ loc_1FEA3:
 
 loc_1FED2:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_1FEDD:
 		pop	bp
@@ -34069,7 +34069,7 @@ loc_2002B:
 
 loc_20039:
 		mov	_boss_phase_frame, 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 
 loc_20044:
 		pop	di
@@ -34371,7 +34371,7 @@ loc_20311:
 		jz	short loc_20326
 		cmp	ax, 1
 		jz	short loc_2032B
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_20330
 		jmp	short loc_20389
 ; ---------------------------------------------------------------------------
@@ -34425,7 +34425,7 @@ loc_20370:
 loc_20389:
 		cmp	_boss_mode_change, 18
 		jb	short loc_2039A
-		cmp	_boss_mode, 0FFh
+		cmp	_boss_mode, -1
 		jz	short loc_2039A
 		call	sub_2023B
 
@@ -34450,7 +34450,7 @@ loc_203B8:
 		jz	short loc_203CD
 		cmp	ax, 1
 		jz	short loc_203D2
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_203D7
 		jmp	short loc_20430
 ; ---------------------------------------------------------------------------
@@ -34504,7 +34504,7 @@ loc_20417:
 loc_20430:
 		cmp	_boss_mode_change, 18
 		jb	short loc_20441
-		cmp	_boss_mode, 0FFh
+		cmp	_boss_mode, -1
 		jz	short loc_20441
 		call	sub_2023B
 
@@ -34529,7 +34529,7 @@ loc_2045F:
 		jz	short loc_20474
 		cmp	ax, 1
 		jz	short loc_20479
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_2047E
 		jmp	short loc_204D7
 ; ---------------------------------------------------------------------------
@@ -34583,7 +34583,7 @@ loc_204BE:
 loc_204D7:
 		cmp	_boss_mode_change, 18
 		jb	short loc_204E8
-		cmp	_boss_mode, 0FFh
+		cmp	_boss_mode, -1
 		jz	short loc_204E8
 		call	sub_2023B
 
@@ -34608,7 +34608,7 @@ loc_20506:
 		jz	short loc_2051B
 		cmp	ax, 1
 		jz	short loc_20520
-		cmp	ax, 0FFh
+		cmp	ax, (-1 and 255)
 		jz	short loc_20525
 		jmp	short loc_2057E
 ; ---------------------------------------------------------------------------
@@ -34662,7 +34662,7 @@ loc_20565:
 loc_2057E:
 		cmp	_boss_mode_change, 18
 		jb	short loc_2058F
-		cmp	_boss_mode, 0FFh
+		cmp	_boss_mode, -1
 		jz	short loc_2058F
 		call	sub_2023B
 
@@ -34680,7 +34680,7 @@ loc_205A4:
 
 loc_205AA:
 		call	boss_phase_end
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	word_2D05A, 0C00h
 		jmp	loc_206B6
 ; ---------------------------------------------------------------------------
@@ -34707,7 +34707,7 @@ loc_205D4:
 
 loc_205ED:
 		call	boss_phase_end pascal, (ET_VERTICAL shl 16) or 0
-		mov	_boss_mode, 0FFh
+		mov	_boss_mode, -1
 		mov	word_2D05A, 0C00h
 		mov	byte_2D02D, 10h
 		jmp	loc_206B6
diff --git a/th04_maine.asm b/th04_maine.asm
index a6e5ec30..7a917a8b 100644
--- a/th04_maine.asm
+++ b/th04_maine.asm
@@ -1554,7 +1554,7 @@ loc_AD95:
 ; ---------------------------------------------------------------------------
 
 loc_ADB1:
-		mov	al, 0FFh	; jumptable 0000A876 case 36
+		mov	al, -1	; jumptable 0000A876 case 36
 		jmp	short loc_ADB7
 ; ---------------------------------------------------------------------------
 
@@ -1639,7 +1639,7 @@ loc_AE45:
 		inc	_cutscene_script_ptr
 		push	word ptr [bp+var_1]
 		call	sub_A847
-		cmp	al, 0FFh
+		cmp	al, -1
 		jnz	short loc_AE2D
 		jmp	short loc_AEC8
 ; ---------------------------------------------------------------------------
diff --git a/th04_memchk.asm b/th04_memchk.asm
index fecc7d8b..a1b41f3c 100644
--- a/th04_memchk.asm
+++ b/th04_memchk.asm
@@ -41,7 +41,7 @@ envp		= word ptr  8
 		ja	short loc_389
 		push	offset DGROUP:aVVxvVSlvsvVvvi ; "ちょっと足りないかも、もう少し増やして"...
 		call	sub_38E
-		mov	ax, 0FFh
+		mov	ax, 255
 		leave
 		retn
 ; ---------------------------------------------------------------------------
diff --git a/th05_main.asm b/th05_main.asm
index 9e8678c9..1f791932 100644
--- a/th05_main.asm
+++ b/th05_main.asm
@@ -3656,7 +3656,7 @@ sub_D3C6	proc near
 		enter	6, 0
 		push	si
 		push	di
-		cmp	word_21D6E, 0FFh
+		cmp	word_21D6E, (-1 and 255)
 		jnz	loc_D456
 		mov	[bp+@@set], offset _linesets
 		xor	di, di
@@ -3715,7 +3715,7 @@ loc_D44B:
 		mov	word_21D6E, 0
 
 loc_D456:
-		cmp	word_21D6E, 40h
+		cmp	word_21D6E, BOSS_PARTICLE_COUNT
 		jge	short loc_D4BE
 		mov	ax, _boss_phase_frame
 		mov	bx, 4
@@ -6089,7 +6089,7 @@ arg_4		= word ptr  8
 		push	di
 		mov	di, offset aBss0_cd2_0
 		mov	[bp+var_6], offset aKao0_cd2_0
-		cmp	[bp+arg_0], 0FFh
+		cmp	[bp+arg_0], (-1 and 255)
 		jz	loc_F432
 		cmp	_Ems, 0
 		jz	loc_F40F
@@ -6161,7 +6161,7 @@ loc_F432:
 		push	[bp+arg_4]
 		push	[bp+arg_2]
 		call	sub_EF2A
-		cmp	[bp+arg_0], 0FFh
+		cmp	[bp+arg_0], (-1 and 255)
 		jz	short loc_F45D
 		call	cdg_put pascal, [bp+arg_4], [bp+arg_2], 2
 		call	cdg_free pascal, 2
@@ -15677,7 +15677,7 @@ loc_18783:
 		mov	_boss_phase_frame, 0
 		mov	_boss_mode, 0
 		mov	_boss_mode_change, 0
-		mov	byte_2D080, 0FFh
+		mov	byte_2D080, -1
 		mov	byte_2D07F, 40h
 		jmp	short loc_1877A
 ; ---------------------------------------------------------------------------
@@ -19852,7 +19852,7 @@ loc_1AE17:
 
 loc_1AE2C:
 		mov	al, byte ptr [bp+var_2]
-		add	al, 0FFh
+		add	al, -1
 		mov	_boss2_mode_change, al
 		mov	_boss_phase, PHASE_BOSS_EXPLODE_SMALL
 		mov	_boss_phase_frame, 0
@@ -27799,7 +27799,7 @@ include th04/sprites/pointnum.asp
 include th05/formats/bb_playchar[data].asm
 byte_21D6C	db 0
 		db 0
-word_21D6E	dw 0FFh
+word_21D6E	dw (-1 and 255)
 byte_21D70	db 0
 		db 0
 word_21D72	dw 0
diff --git a/th05_maine.asm b/th05_maine.asm
index dc1fed31..4e009a5b 100644
--- a/th05_maine.asm
+++ b/th05_maine.asm
@@ -1251,7 +1251,7 @@ loc_AF18:
 ; ---------------------------------------------------------------------------
 
 loc_AF8B:
-		mov	al, 0FFh	; jumptable 0000A9F2 case 36
+		mov	al, -1	; jumptable 0000A9F2 case 36
 		jmp	short loc_AF91
 ; ---------------------------------------------------------------------------
 
@@ -1339,7 +1339,7 @@ loc_B01D:
 		inc	_cutscene_script_ptr
 		push	[bp+var_3]
 		call	sub_A9C3
-		cmp	al, 0FFh
+		cmp	al, -1
 		jnz	short loc_B005
 		jmp	loc_B196
 ; ---------------------------------------------------------------------------
diff --git a/th05_memchk.asm b/th05_memchk.asm
index 221df847..9098e17f 100644
--- a/th05_memchk.asm
+++ b/th05_memchk.asm
@@ -42,7 +42,7 @@ start proc near
 		cmp	bx, 32500
 		jnb	short loc_131
 		mov	di, offset aVVxvVBagbgvgkv ; "ちょっと、メモリが足りないかも\r\nこのゲ"...
-		mov	byte_236, 0FFh
+		mov	byte_236, 255
 
 loc_131:
 		xor	dx, dx