diff --git a/.vscode/settings.json b/.vscode/settings.json
index f7b26e28..45145d9e 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,4 +1,11 @@
 {
+  "z80-macroasm.format.enabled": true,
+  "z80-macroasm.format.baseIndent": 1,
+  "z80-macroasm.format.whitespaceAfterInstruction": "tab",
+  "z80-macroasm.format.uppercaseKeywords": true,
+  "z80-macroasm.format.spaceAfterArgument": true,
+  "z80-macroasm.format.hexaNumberStyle": "motorola",
+  "z80-macroasm.format.hexaNumberCase": true,
   "files.trimTrailingWhitespace": false,
   "files.eol": "\r\n",
   "files.associations": {
diff --git a/Source/HBIOS/ch376-native/scsi-drv/class_scsi.c.s b/Source/HBIOS/ch376-native/scsi-drv/class_scsi.c.s
index 31d4623d..3976a6a0 100644
--- a/Source/HBIOS/ch376-native/scsi-drv/class_scsi.c.s
+++ b/Source/HBIOS/ch376-native/scsi-drv/class_scsi.c.s
@@ -37,10 +37,6 @@ _scsi_command_block_wrapper:
 	DEFS 15
 _next_tag:
 	DEFS 2
-_csw:
-	DEFS 13
-_scsi_packet_request_sense:
-	DEFS 12
 	
 #ENDIF
 	
@@ -56,7 +52,7 @@ _scsi_packet_request_sense:
 ;--------------------------------------------------------
 ; code
 ;--------------------------------------------------------
-;source-doc/scsi-drv/class_scsi.c:13: usb_error do_scsi_cmd(device_config_storage *const       dev,
+;source-doc/scsi-drv/class_scsi.c:11: usb_error do_scsi_cmd(device_config_storage *const       dev,
 ; ---------------------------------
 ; Function do_scsi_cmd
 ; ---------------------------------
@@ -64,15 +60,34 @@ _do_scsi_cmd:
 	push	ix
 	ld	ix,0
 	add	ix,sp
-	ld	hl, -8
+	ld	hl, -21
 	add	hl, sp
 	ld	sp, hl
-;source-doc/scsi-drv/class_scsi.c:20: cbw->dCBWTag[0] = next_tag++;
+;source-doc/scsi-drv/class_scsi.c:17: _scsi_command_status_wrapper csw = {{{0}}};
+	ld	a,0x00
+	ld	(ix-21),a
+	ld	(ix-20),a
+	ld	(ix-19),a
+	ld	(ix-18),a
+	xor	a
+	ld	(ix-17),a
+	ld	(ix-16),a
+	xor	a
+	ld	(ix-15),a
+	ld	(ix-14),a
+	ld	a,0x00
+	ld	(ix-13),a
+	ld	(ix-12),a
+	ld	(ix-11),a
+	ld	(ix-10),a
+	ld	(ix-9),0x00
+;source-doc/scsi-drv/class_scsi.c:19: cbw->dCBWTag[0] = next_tag++;
 	ld	c,(ix+6)
 	ld	b,(ix+7)
 	ld	hl,0x0004
 	add	hl, bc
-	ex	(sp), hl
+	ld	(ix-8),l
+	ld	(ix-7),h
 	ld	a, (_next_tag)
 	ld	e, a
 	ld	hl,_next_tag + 1
@@ -80,24 +95,24 @@ _do_scsi_cmd:
 	ld	hl, (_next_tag)
 	inc	hl
 	ld	(_next_tag), hl
-	pop	hl
-	push	hl
+	ld	l,(ix-8)
+	ld	h,(ix-7)
 	ld	(hl), e
 	inc	hl
 	ld	(hl), d
-;source-doc/scsi-drv/class_scsi.c:22: if (!send)
+;source-doc/scsi-drv/class_scsi.c:21: if (!send)
 	bit	0,(ix+10)
 	jr	NZ,l_do_scsi_cmd_00102
-;source-doc/scsi-drv/class_scsi.c:23: cbw->bmCBWFlags = 0x80;
+;source-doc/scsi-drv/class_scsi.c:22: cbw->bmCBWFlags = 0x80;
 	ld	hl,0x000c
 	add	hl, bc
 	ld	(hl),0x80
 l_do_scsi_cmd_00102:
-;source-doc/scsi-drv/class_scsi.c:25: critical_begin();
+;source-doc/scsi-drv/class_scsi.c:24: critical_begin();
 	push	bc
 	call	_critical_begin
 	pop	bc
-;source-doc/scsi-drv/class_scsi.c:28: &dev->endpoints[ENDPOINT_BULK_OUT]));
+;source-doc/scsi-drv/class_scsi.c:27: &dev->endpoints[ENDPOINT_BULK_OUT]));
 	ld	a,(ix+4)
 	ld	(ix-6),a
 	ld	e, a
@@ -140,7 +155,7 @@ l_do_scsi_cmd_00102:
 	ld	a, l
 	or	a
 	jp	NZ, l_do_scsi_cmd_00120
-;source-doc/scsi-drv/class_scsi.c:30: if (cbw->dCBWDataTransferLength != 0) {
+;source-doc/scsi-drv/class_scsi.c:29: if (cbw->dCBWDataTransferLength != 0) {
 	ld	hl,8
 	add	hl, bc
 	ld	c, (hl)
@@ -155,15 +170,15 @@ l_do_scsi_cmd_00102:
 	or	b
 	or	c
 	jr	Z,l_do_scsi_cmd_00113
-;source-doc/scsi-drv/class_scsi.c:33: &dev->endpoints[ENDPOINT_BULK_IN]));
+;source-doc/scsi-drv/class_scsi.c:32: &dev->endpoints[ENDPOINT_BULK_IN]));
 	ld	(ix-2),c
 	ld	(ix-1),b
 	ld	c,(ix+8)
 	ld	b,(ix+9)
-;source-doc/scsi-drv/class_scsi.c:31: if (!send) {
+;source-doc/scsi-drv/class_scsi.c:30: if (!send) {
 	bit	0,(ix+10)
 	jr	NZ,l_do_scsi_cmd_00110
-;source-doc/scsi-drv/class_scsi.c:33: &dev->endpoints[ENDPOINT_BULK_IN]));
+;source-doc/scsi-drv/class_scsi.c:32: &dev->endpoints[ENDPOINT_BULK_IN]));
 	ld	a,(ix-6)
 	add	a,0x06
 	ld	e, a
@@ -195,7 +210,7 @@ l_do_scsi_cmd_00102:
 	jr	Z,l_do_scsi_cmd_00113
 	jr	l_do_scsi_cmd_00120
 l_do_scsi_cmd_00110:
-;source-doc/scsi-drv/class_scsi.c:37: &dev->endpoints[ENDPOINT_BULK_OUT]));
+;source-doc/scsi-drv/class_scsi.c:36: &dev->endpoints[ENDPOINT_BULK_OUT]));
 	ld	l,(ix-4)
 	ld	h,(ix-3)
 	ld	a, (hl)
@@ -220,7 +235,7 @@ l_do_scsi_cmd_00110:
 	or	a
 	jr	NZ,l_do_scsi_cmd_00120
 l_do_scsi_cmd_00113:
-;source-doc/scsi-drv/class_scsi.c:42: usb_data_in_transfer((uint8_t *)&csw, sizeof(_scsi_command_status_wrapper), dev->address, &dev->endpoints[ENDPOINT_BULK_IN]));
+;source-doc/scsi-drv/class_scsi.c:41: usb_data_in_transfer((uint8_t *)&csw, sizeof(_scsi_command_status_wrapper), dev->address, &dev->endpoints[ENDPOINT_BULK_IN]));
 	ld	a,(ix-6)
 	add	a,0x06
 	ld	c, a
@@ -241,7 +256,8 @@ l_do_scsi_cmd_00113:
 	inc	sp
 	ld	hl,0x000d
 	push	hl
-	ld	hl,_csw
+	ld	hl,5
+	add	hl, sp
 	push	hl
 	call	_usb_data_in_transfer
 	pop	af
@@ -251,38 +267,40 @@ l_do_scsi_cmd_00113:
 	ld	a, l
 	or	a
 	jr	NZ,l_do_scsi_cmd_00120
-;source-doc/scsi-drv/class_scsi.c:44: if (csw.bCSWStatus != 0 && csw.dCSWTag[0] != cbw->dCBWTag[0])
-	ld	a, (_csw + 12)
+;source-doc/scsi-drv/class_scsi.c:43: if (csw.bCSWStatus != 0 || csw.dCSWTag[0] != cbw->dCBWTag[0])
+	ld	a,(ix-9)
 	or	a
-	jr	Z,l_do_scsi_cmd_00117
-	ld	bc, (_csw + 4)
-	pop	hl
-	ld	a,(hl)
-	push	hl
+	jr	NZ,l_do_scsi_cmd_00116
+	ld	c,(ix-17)
+	ld	b,(ix-16)
+	ld	l,(ix-8)
+	ld	h,(ix-7)
+	ld	a, (hl)
 	inc	hl
 	ld	h, (hl)
 	ld	l, a
 	xor	a
 	sbc	hl,bc
 	jr	Z,l_do_scsi_cmd_00117
-;source-doc/scsi-drv/class_scsi.c:45: result = USB_ERR_FAIL;
+l_do_scsi_cmd_00116:
+;source-doc/scsi-drv/class_scsi.c:44: result = USB_ERR_FAIL;
 	ld	l,0x0e
 	jr	l_do_scsi_cmd_00120
 l_do_scsi_cmd_00117:
-;source-doc/scsi-drv/class_scsi.c:47: result = USB_ERR_OK;
+;source-doc/scsi-drv/class_scsi.c:46: result = USB_ERR_OK;
 	ld	l,0x00
-;source-doc/scsi-drv/class_scsi.c:49: done:
+;source-doc/scsi-drv/class_scsi.c:48: done:
 l_do_scsi_cmd_00120:
-;source-doc/scsi-drv/class_scsi.c:50: critical_end();
+;source-doc/scsi-drv/class_scsi.c:49: critical_end();
 	push	hl
 	call	_critical_end
 	pop	hl
-;source-doc/scsi-drv/class_scsi.c:51: return result;
-;source-doc/scsi-drv/class_scsi.c:52: }
+;source-doc/scsi-drv/class_scsi.c:50: return result;
+;source-doc/scsi-drv/class_scsi.c:51: }
 	ld	sp, ix
 	pop	ix
 	ret
-;source-doc/scsi-drv/class_scsi.c:54: usb_error scsi_test(device_config_storage *const dev) {
+;source-doc/scsi-drv/class_scsi.c:53: usb_error scsi_test(device_config_storage *const dev) {
 ; ---------------------------------
 ; Function scsi_test
 ; ---------------------------------
@@ -293,7 +311,7 @@ _scsi_test:
 	ld	hl, -27
 	add	hl, sp
 	ld	sp, hl
-;source-doc/scsi-drv/class_scsi.c:56: cbw_scsi.cbw = scsi_command_block_wrapper;
+;source-doc/scsi-drv/class_scsi.c:55: cbw_scsi.cbw = scsi_command_block_wrapper;
 	ld	hl,0
 	add	hl, sp
 	ld	e,l
@@ -302,7 +320,7 @@ _scsi_test:
 	ld	bc,0x000f
 	ld	hl,_scsi_command_block_wrapper
 	ldir
-;source-doc/scsi-drv/class_scsi.c:57: memset(&cbw_scsi.test, 0, sizeof(_scsi_packet_test));
+;source-doc/scsi-drv/class_scsi.c:56: memset(&cbw_scsi.test, 0, sizeof(_scsi_packet_test));
 	ld	hl,17
 	add	hl, sp
 	ld	b,0x06
@@ -314,11 +332,11 @@ l_scsi_test_00103:
 	inc	hl
 	djnz	l_scsi_test_00103
 	pop	bc
-;source-doc/scsi-drv/class_scsi.c:59: cbw_scsi.cbw.bCBWLUN                = 0;
+;source-doc/scsi-drv/class_scsi.c:58: cbw_scsi.cbw.bCBWLUN                = 0;
 	ld	(ix-14),0x00
-;source-doc/scsi-drv/class_scsi.c:60: cbw_scsi.cbw.bCBWCBLength           = sizeof(_scsi_packet_test);
+;source-doc/scsi-drv/class_scsi.c:59: cbw_scsi.cbw.bCBWCBLength           = sizeof(_scsi_packet_test);
 	ld	(ix-13),0x0c
-;source-doc/scsi-drv/class_scsi.c:61: cbw_scsi.cbw.dCBWDataTransferLength = 0;
+;source-doc/scsi-drv/class_scsi.c:60: cbw_scsi.cbw.dCBWDataTransferLength = 0;
 	ld	hl,0x0008
 	add	hl, bc
 	xor	a
@@ -329,7 +347,7 @@ l_scsi_test_00103:
 	ld	(hl), a
 	inc	hl
 	ld	(hl), a
-;source-doc/scsi-drv/class_scsi.c:63: return do_scsi_cmd(dev, &cbw_scsi.cbw, 0, false);
+;source-doc/scsi-drv/class_scsi.c:62: return do_scsi_cmd(dev, &cbw_scsi.cbw, 0, false);
 	xor	a
 	push	af
 	inc	sp
@@ -340,11 +358,11 @@ l_scsi_test_00103:
 	ld	h,(ix+5)
 	push	hl
 	call	_do_scsi_cmd
-;source-doc/scsi-drv/class_scsi.c:64: }
+;source-doc/scsi-drv/class_scsi.c:63: }
 	ld	sp,ix
 	pop	ix
 	ret
-;source-doc/scsi-drv/class_scsi.c:68: usb_error scsi_request_sense(device_config_storage *const dev, scsi_sense_result *const sens_result) {
+;source-doc/scsi-drv/class_scsi.c:67: usb_error scsi_request_sense(device_config_storage *const dev, scsi_sense_result *const sens_result) {
 ; ---------------------------------
 ; Function scsi_request_sense
 ; ---------------------------------
@@ -355,7 +373,7 @@ _scsi_request_sense:
 	ld	hl, -27
 	add	hl, sp
 	ld	sp, hl
-;source-doc/scsi-drv/class_scsi.c:70: cbw_scsi.cbw           = scsi_command_block_wrapper;
+;source-doc/scsi-drv/class_scsi.c:69: cbw_scsi.cbw           = scsi_command_block_wrapper;
 	ld	hl,0
 	add	hl, sp
 	ld	e,l
@@ -364,7 +382,7 @@ _scsi_request_sense:
 	ld	bc,0x000f
 	ld	hl,_scsi_command_block_wrapper
 	ldir
-;source-doc/scsi-drv/class_scsi.c:71: cbw_scsi.request_sense = scsi_packet_request_sense;
+;source-doc/scsi-drv/class_scsi.c:70: cbw_scsi.request_sense = scsi_packet_request_sense;
 	ld	hl,17
 	add	hl, sp
 	ex	de, hl
@@ -372,11 +390,11 @@ _scsi_request_sense:
 	ld	hl,_scsi_packet_request_sense
 	ldir
 	pop	bc
-;source-doc/scsi-drv/class_scsi.c:73: cbw_scsi.cbw.bCBWLUN                = 0;
+;source-doc/scsi-drv/class_scsi.c:72: cbw_scsi.cbw.bCBWLUN                = 0;
 	ld	(ix-14),0x00
-;source-doc/scsi-drv/class_scsi.c:74: cbw_scsi.cbw.bCBWCBLength           = sizeof(_scsi_packet_request_sense);
+;source-doc/scsi-drv/class_scsi.c:73: cbw_scsi.cbw.bCBWCBLength           = sizeof(_scsi_packet_request_sense);
 	ld	(ix-13),0x0c
-;source-doc/scsi-drv/class_scsi.c:75: cbw_scsi.cbw.dCBWDataTransferLength = sizeof(scsi_sense_result);
+;source-doc/scsi-drv/class_scsi.c:74: cbw_scsi.cbw.dCBWDataTransferLength = sizeof(scsi_sense_result);
 	ld	hl,0x0008
 	add	hl, bc
 	ld	(hl),0x12
@@ -387,7 +405,7 @@ _scsi_request_sense:
 	ld	(hl), a
 	inc	hl
 	ld	(hl), a
-;source-doc/scsi-drv/class_scsi.c:77: return do_scsi_cmd(dev, &cbw_scsi.cbw, sens_result, false);
+;source-doc/scsi-drv/class_scsi.c:76: return do_scsi_cmd(dev, &cbw_scsi.cbw, sens_result, false);
 	ld	e,(ix+6)
 	ld	d,(ix+7)
 	xor	a
@@ -399,37 +417,10 @@ _scsi_request_sense:
 	ld	h,(ix+5)
 	push	hl
 	call	_do_scsi_cmd
-;source-doc/scsi-drv/class_scsi.c:78: }
+;source-doc/scsi-drv/class_scsi.c:77: }
 	ld	sp,ix
 	pop	ix
 	ret
-_scsi_command_block_wrapper:
-	DEFB +0x55
-	DEFB +0x53
-	DEFB +0x42
-	DEFB +0x43
-	DEFW +0x0000
-	DEFW +0x0000
-	DEFB +0x00,0x00, +0x00, +0x00
-	DEFB +0x00
-	DEFB +0x00
-	DEFB +0x00
-_next_tag:
-	DEFW +0x0000
-_csw:
-	DEFB +0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB 0x00
-	DEFB +0x00
 _scsi_packet_request_sense:
 	DEFB +0x03
 	DEFB +0x00
@@ -443,3 +434,16 @@ _scsi_packet_request_sense:
 	DEFB +0x00
 	DEFB +0x00
 	DEFB +0x00
+_scsi_command_block_wrapper:
+	DEFB +0x55
+	DEFB +0x53
+	DEFB +0x42
+	DEFB +0x43
+	DEFW +0x0000
+	DEFW +0x0000
+	DEFB +0x00,0x00, +0x00, +0x00
+	DEFB +0x00
+	DEFB +0x00
+	DEFB +0x00
+_next_tag:
+	DEFW +0x0000
diff --git a/Source/HBIOS/ch376-native/source-doc/scsi-drv/class_scsi.c b/Source/HBIOS/ch376-native/source-doc/scsi-drv/class_scsi.c
index 5a5a0e51..755681d3 100644
--- a/Source/HBIOS/ch376-native/source-doc/scsi-drv/class_scsi.c
+++ b/Source/HBIOS/ch376-native/source-doc/scsi-drv/class_scsi.c
@@ -8,14 +8,13 @@ _scsi_command_block_wrapper scsi_command_block_wrapper = {{0x55, 0x53, 0x42, 0x4
 
 uint16_t next_tag = 0;
 
-_scsi_command_status_wrapper csw = {{{0}}};
-
 usb_error do_scsi_cmd(device_config_storage *const       dev,
                       _scsi_command_block_wrapper *const cbw,
                       void *const                        send_receive_buffer,
                       const bool                         send) {
 
   usb_error result;
+  _scsi_command_status_wrapper csw = {{{0}}};
 
   cbw->dCBWTag[0] = next_tag++;
 
@@ -41,7 +40,7 @@ usb_error do_scsi_cmd(device_config_storage *const       dev,
   CHECK(
       usb_data_in_transfer((uint8_t *)&csw, sizeof(_scsi_command_status_wrapper), dev->address, &dev->endpoints[ENDPOINT_BULK_IN]));
 
-  if (csw.bCSWStatus != 0 && csw.dCSWTag[0] != cbw->dCBWTag[0])
+  if (csw.bCSWStatus != 0 || csw.dCSWTag[0] != cbw->dCBWTag[0])
     result = USB_ERR_FAIL;
   else
     result = USB_ERR_OK;
@@ -63,7 +62,7 @@ usb_error scsi_test(device_config_storage *const dev) {
   return do_scsi_cmd(dev, &cbw_scsi.cbw, 0, false);
 }
 
-_scsi_packet_request_sense scsi_packet_request_sense = {0x03, 0, 0, 0, 18, 0, {0, 0, 0, 0, 0, 0}};
+const _scsi_packet_request_sense scsi_packet_request_sense = {0x03, 0, 0, 0, 18, 0, {0, 0, 0, 0, 0, 0}};
 
 usb_error scsi_request_sense(device_config_storage *const dev, scsi_sense_result *const sens_result) {
   cbw_scsi_request_sense cbw_scsi;
diff --git a/Source/HBIOS/ez80cpudrv.asm b/Source/HBIOS/ez80cpudrv.asm
index 510a8eec..e4d1499c 100644
--- a/Source/HBIOS/ez80cpudrv.asm
+++ b/Source/HBIOS/ez80cpudrv.asm
@@ -342,24 +342,20 @@ _EZ80_CPY_UHL_TO_EHL:
 
 ; set the upper byte (u of DE) to MB.
 _EZ80_EXTN_DE_TO_MB_DE:
-	PUSH	IY
-	.DB	$5B, $FD, $21, $00, $00, $00		; LD.LIL	IY, 0
+	.DB	$49, $D5				; PUSH.L 	DE
+	.DB	$5B, $FD, $21, $00, $00, $00		; LD.LIL 	IY, 0
 	.DB	$49, $FD, $39				; ADD.L		IY, SP
-	.DB	$49, $FD, $1F, $FD                	; LD.L		(IY-3), DE
-	.DB	$ED, $6E                    		; LD		A, MB
-	.DB	$49, $FD, $77, $FF			; LD.L		(IY-1), A
-	.DB	$49, $FD, $17, $FD			; LD.L		DE, (IY-3)
-	POP	IY
+	.DB	$ED, $6E              			; LD 		A, MB
+	.DB	$5B, $FD, $77, $02			; LD.LIL 	(IY+2), A
+	.DB	$49, $D1				; POP.L		DE
 	RET
 
 ; set the upper byte (u of IY) to MB.
 _EZ80_EXTN_IY_TO_MB_IY:
-	PUSH	IX
-	.DB	$5B, $DD, $21, $00, $00, $00		; LD.LIL	IX, 0
-	.DB	$49, $DD, $39				; ADD.L		IX, SP
-	.DB	$49, $DD, $3E, $FD			; LD.L		(IX-3), IY
+	.DB	$49, $FD, $E5				; PUSH.L	IY
+	.DB	$5B, $FD, $21, $00, $00, $00		; LD.LIL	IY, 0
+	.DB	$49, $FD, $39				; ADD.L		IY, SP
 	.DB	$ED, $6E				; LD		A, MB
-	.DB	$49, $DD, $77, $FF			; LD.L		(IX-1), A
-	.DB	$49, $DD, $31, $FD			; LD.L		IY, (IX-3)
-	POP	IX
+	.DB	$5B, $FD, $77, $02			; LD.LIL	(IY+2), A
+	.DB	$49, $FD, $E1				; POP.L		IY
 	RET