From 158cc65da3abf5f98e5d438b8c91a8dd3053fdd2 Mon Sep 17 00:00:00 2001
From: Jeff Parsons <Jeff@pcjs.org>
Date: Mon, 13 Apr 2015 14:02:02 -0700
Subject: [PATCH] Cleaned up DMA port handling and minor tweaks

---
 .../pc/bios/compaq/deskpro386/1988-01-28.nasm |  78 ++++--
 devices/pc/bios/compaq/deskpro386/notes.md    | 226 ++++++++++++++++++
 .../compaq/deskpro386/ega/2048kb/machine.xml  |   2 +-
 modules/pcjs/lib/chipset.js                   | 103 ++++----
 modules/pcjs/lib/computer.js                  |   4 +
 modules/pcjs/lib/debugger.js                  |  16 +-
 modules/pcjs/lib/ram.js                       |   3 +-
 modules/pcjs/lib/serialport.js                |  23 +-
 modules/pcjs/lib/video.js                     |  16 +-
 modules/pcjs/lib/x86cpu.js                    |  30 +--
 modules/pcjs/lib/x86func.js                   |  59 ++---
 modules/pcjs/lib/x86ops.js                    |  28 ++-
 modules/pcjs/lib/x86seg.js                    |  28 +--
 modules/shared/lib/embed.js                   |   2 +-
 modules/shared/lib/strlib.js                  |   6 +-
 modules/shared/lib/usrlib.js                  |   4 +-
 16 files changed, 453 insertions(+), 175 deletions(-)

diff --git a/devices/pc/bios/compaq/deskpro386/1988-01-28.nasm b/devices/pc/bios/compaq/deskpro386/1988-01-28.nasm
index 4e62f2d91..5863a787a 100644
--- a/devices/pc/bios/compaq/deskpro386/1988-01-28.nasm
+++ b/devices/pc/bios/compaq/deskpro386/1988-01-28.nasm
@@ -1,6 +1,6 @@
 ;
 ; ROM BIOS for Compaq DeskPro 386-16
-; Rev J.4, from parts 109592-001 and 109591-001, dated 1988-Jan-28
+; Rev J.4, from parts 109592-001 and 109591-001, dated '01/28/88'
 ; (C)Copyright COMPAQ Computer Corporation 1982,83,84,85,86,87-All rights reserved.
 ;
 ; Listing produced by NDISASM, 2015-Apr-04
@@ -2287,7 +2287,7 @@ x9311:	cmp	ah,al			; 00009311  3AE0  ':.'
 
 	db	0x0D,0x0A,'Non-System disk or disk error',0x0D,0x0A,'replace and strike any key when ready',0x0D,0x0A,'$',0x0D,0x0A,'602-Diskette Boot Record Error',0x0D,0x0A,'$'
 
-	mov	bx,0x2			; 00009380  BB0200  '...'
+x9380:	mov	bx,0x2			; 00009380  BB0200  '...'
 	mov	cx,0xfde8		; 00009383  B9E8FD  '...'
 x9386:	mov	al,0x80			; 00009386  B080  '..'
 	out	0x70,al			; 00009388  E670  '.p'
@@ -2968,6 +2968,9 @@ x9bed:	mov	al,ah			; 00009BED  8AC4  '..'
 	loop	x9bed			; 00009BF6  E2F5  '..'
 	jmp	bp			; 00009BF8  FFE5  '..'
 
+	;
+	; Clear the screen (DS=F000, BX=BA77 for CGA or BA86 for Mono)
+	;
 x9bfa:	mov	ax,0x720		; 00009BFA  B82007  '. .'
 	mov	es,[bx+0x6]		; 00009BFD  8E4706  '.G.'
 	xor	di,di			; 00009C00  33FF  '3.'
@@ -4619,7 +4622,7 @@ xa9e9:	cs	rep movsw		; 0000A9E9  F32EA5  '...'
 	and	byte [0x87],0xfb	; 0000AA17  80268700FB  '.&...'
 	jmp	short xaa2f		; 0000AA1C  EB11  '..'
 
-xaa1e:	mov	bx,0xba77		; 0000AA1E  BB77BA  '.w.'
+xaa1e:	mov	bx,xba77		; 0000AA1E  BB77BA  '.w.'
 	mov	es,[cs:bx+0x6]		; 0000AA21  2E8E4706  '..G.'
 	call	x9e1c			; 0000AA25  E8F4F3  '...'
 	jz	xaa2f			; 0000AA28  7405  't.'
@@ -4744,7 +4747,7 @@ xaac9:	and	byte [0x10],0xcf	; 0000AAC9  80261000CF  '.&...'
 	call	xc791			; 0000AB1B  E8731C  '.s.'
 xab1e:	ret				; 0000AB1E  C3  '.'
 
-xab1f:	mov	dx,0xba77		; 0000AB1F  BA77BA  '.w.'
+xab1f:	mov	dx,xba77		; 0000AB1F  BA77BA  '.w.'
 	mov	bx,dx			; 0000AB22  8BDA  '..'
 	add	bx,byte +0xf		; 0000AB24  83C30F  '...'
 	or	al,al			; 0000AB27  0AC0  0x0A,'.'
@@ -4807,7 +4810,7 @@ xab96:	mov	al,0x58			; 0000AB96  B058  '.X'
 	out	0x84,al			; 0000AB98  E684  '..'
 	push	cs			; 0000AB9A  0E  '.'
 	pop	ds			; 0000AB9B  1F  '.'
-	mov	bx,0xba77		; 0000AB9C  BB77BA  '.w.'
+	mov	bx,xba77		; 0000AB9C  BB77BA  '.w.'
 xab9f:	mov	al,0x59			; 0000AB9F  B059  '.Y'
 	out	0x84,al			; 0000ABA1  E684  '..'
 	mov	es,[bx+0x6]		; 0000ABA3  8E4706  '.G.'
@@ -6103,23 +6106,30 @@ xb68a:	stc				; 0000B68A  F9  '.'
 	db	' 605-Diskette Drive Type Error-(Run Setup)',0x0D,0x0A
 	db	'     Insert DIAGNOSTIC diskette in Drive A:',0x0D,0x0A
 
-	db	0xD8			; 0000BA77  D8
-	add	dx,sp			; 0000BA78  03D4  '..'
-	sub	[si+0xf0],si		; 0000BA7A  29B4F000  ')...'
-	mov	ax,0x6000		; 0000BA7E  B80060  '..`'
-	mov	dh,[bx+0x1e]		; 0000BA81  8AB71E00  '....'
-	inc	ax			; 0000BA85  40  '@'
-	mov	ax,0xb403		; 0000BA86  B803B4  '...'
-	sub	sp,dx			; 0000BA89  29D4  ').'
-	lock	add [bx+si+0x6000],dh	; 0000BA8B  F000B00060  '....`'
-	imul	si,[bx+0x21],word 0xbd10; 0000BA90  69B7210010BD  'i.!...'
-	wait				; 0000BA96  9B  '.'
-	mov	dx,0xe5e9		; 0000BA97  BAE9E5  '...'
-	fdiv	dword [bx+si+0xe68e]	; 0000BA9A  D8B08EE6  '....'
-	jo	xbad3			; 0000BA9E  7033  'p3'
-	shl	dh,0x71			; 0000BAA0  C0E671  '..q'
-	mov	al,0x40			; 0000BAA3  B040  '.@'
-	out	0x86,al			; 0000BAA5  E686  '..'
+	;
+	; Video card data
+	;
+xba77:	dw	0x03D8			; 0000BA77  D803 	; +0x00: I/O address of Mode Select Register (CGA)
+	db	0xD4,0x29,0xB4,0xF0	; 0000BA79  D429B4F0
+	dw	0xB800			; 0000BA7D  00B8	; +0x06: real-mode segment of frame buffer
+	db	0x00,0x60,0x8A,0xB7	; 0000BA7F  00608AB7
+	db	0x1E,0x00,0x40		; 0000BA83  1E0040
+
+xba86:	dw	0x03B8			; 0000BA86  B803	; +0x00: I/O address of Mode Select Register (Mono)
+	db	0xB4,0x29,0xD4,0xF0	; 0000BA88  B429D4F0
+	dw	0xB000			; 0000BA8C  00B0	; +0x06: real-mode segment of frame buffer
+	db	0x00,0x60,0x69,0xB7	; 0000BA8E  006069B7
+	db	0x21,0x00,0x10		; 0000BA92  210010
+
+	mov	bp,0xba9b		; 0000BA95  BD9BBA
+	jmp	x9380			; 0000BA98  E9E5D8
+
+	mov	al,0x8e			; 0000BA9B  B08E
+	out	0x70,al			; 0000BA9D  E670
+	xor	ax,ax			; 0000BA9F  33C0
+	out	0x71,al			; 0000BAA1  E671
+	mov	al,0x40			; 0000BAA3  B040
+	out	0x86,al			; 0000BAA5  E686
 
 xbaa7:	cli				; 0000BAA7  FA  '.'
 	mov	al,0xf			; 0000BAA8  B00F  '..'
@@ -9921,11 +9931,15 @@ xd9db:	mov	ax,0x40			; 0000D9DB  B84000  '.@.'
 	or	bx,bx			; 0000D9ED  0BDB  '..'
 	jnz	xd9f4			; 0000D9EF  7503  'u.'
 	jmp	xda8c			; 0000D9F1  E99800  '...'
-
+;
+; At checkpoint 0x6B, the conventional+extended memory test has been completed, and you should
+; see a total at the top of the screen (eg, "01792 KB OK").
+;
 xd9f4:	mov	al,0x6b			; 0000D9F4  B06B  '.k'
 	out	0x84,al			; 0000D9F6  E684  '..'
 	mov	ax,0x1c00		; 0000D9F8  B8001C  '...'
 	mov	ds,ax			; 0000D9FB  8ED8  '..'
+
 	test	word [0x64],0x1		; 0000D9FD  F70664000100  '..d...'
 	jz	xda1b			; 0000DA03  7416  't.'
 	call	xc786			; 0000DA05  E87EED  '.~.'
@@ -9935,6 +9949,7 @@ xd9f4:	mov	al,0x6b			; 0000D9F4  B06B  '.k'
 	mov	cl,[0x69]		; 0000DA10  8A0E6900  '..i.'
 	mov	dx,[0x67]		; 0000DA14  8B166700  '..g.'
 	call	x822d			; 0000DA18  E812A8  '...'
+
 xda1b:	test	word [0x64],0x4		; 0000DA1B  F70664000400  '..d...'
 	jz	xda39			; 0000DA21  7416  't.'
 	call	xc786			; 0000DA23  E860ED  '.`.'
@@ -9944,6 +9959,7 @@ xda1b:	test	word [0x64],0x4		; 0000DA1B  F70664000400  '..d...'
 	mov	cl,[0x6d]		; 0000DA2E  8A0E6D00  '..m.'
 	mov	dx,[0x6b]		; 0000DA32  8B166B00  '..k.'
 	call	x8242			; 0000DA36  E809A8  '...'
+
 xda39:	test	word [0x64],0x2		; 0000DA39  F70664000200  '..d...'
 	jz	xda57			; 0000DA3F  7416  't.'
 	call	xc786			; 0000DA41  E842ED  '.B.'
@@ -9952,7 +9968,13 @@ xda39:	test	word [0x64],0x2		; 0000DA39  F70664000200  '..d...'
 	mov	si,cx			; 0000DA4A  8BF1  '..'
 	mov	cl,[0x71]		; 0000DA4C  8A0E7100  '..q.'
 	mov	dx,[0x6f]		; 0000DA50  8B166F00  '..o.'
+;
+; During the next call, the following additional text may be displayed on the screen:
+;
+;   F00000 02 201-Memory Error
+;
 	call	x822d			; 0000DA54  E8D6A7  '...'
+
 xda57:	test	word [0x64],0x8		; 0000DA57  F70664000800  '..d...'
 	jz	xda75			; 0000DA5D  7416  't.'
 	call	xc786			; 0000DA5F  E824ED  '.$.'
@@ -9961,7 +9983,13 @@ xda57:	test	word [0x64],0x8		; 0000DA57  F70664000800  '..d...'
 	mov	si,cx			; 0000DA68  8BF1  '..'
 	mov	cl,[0x75]		; 0000DA6A  8A0E7500  '..u.'
 	mov	dx,[0x73]		; 0000DA6E  8B167300  '..s.'
+;
+; During the next call, the following additional text may be displayed on the screen:
+;
+;   F00000 FF 203-Memory Address Error
+;
 	call	x8242			; 0000DA72  E8CDA7  '...'
+
 xda75:	test	word [0x64],0x10	; 0000DA75  F70664001000  '..d...'
 	jz	xda8c			; 0000DA7B  740F  't.'
 	call	xc786			; 0000DA7D  E806ED  '...'
@@ -9969,6 +9997,7 @@ xda75:	test	word [0x64],0x10	; 0000DA75  F70664001000  '..d...'
 	mov	bx,0xb68c		; 0000DA83  BB8CB6  '...'
 	mov	cx,0x1a			; 0000DA86  B91A00  '...'
 	call	xc745			; 0000DA89  E8B9EC  '...'
+
 xda8c:	test	word [0x64],0xffff	; 0000DA8C  F7066400FFFF  '..d...'
 	jz	xdaac			; 0000DA92  7418  't.'
 	call	xc786			; 0000DA94  E8EFEC  '...'
@@ -14293,6 +14322,7 @@ xffb3:	pop	ds			; 0000FFB3  1F  '.'
 
 	jmp	0xf000:reset		; 0000FFF0  EA05F900F0
 
-	db	' 01/28/88'
+	db	0x20
+	db	'01/28/88'
 	db	0xFC			; 0000FFFE  FC
 	db	0x98			; 0000FFFF  98
diff --git a/devices/pc/bios/compaq/deskpro386/notes.md b/devices/pc/bios/compaq/deskpro386/notes.md
index 492d1ca29..bd0373ccb 100644
--- a/devices/pc/bios/compaq/deskpro386/notes.md
+++ b/devices/pc/bios/compaq/deskpro386/notes.md
@@ -182,3 +182,229 @@ But when we stopped here next, it was no longer good:
 	%00FF0740  0000  0000  0000  0000 - 0000  0000  0000  0000   ................
 
 Turns out this is because the A20 line has been disabled.
+
+-------------------------------------------------------------------------------------------------
+
+Let's look at a complete run:
+
+	EAX=00000000 EBX=00000000 ECX=00000000 EDX=00000304 
+	ESP=00000000 EBP=00000000 ESI=00000000 EDI=00000000 
+	SS=0000 DS=0000 ES=0000 FS=0000 GS=0000 PS=00000002 V0 D0 I0 T0 S0 Z0 A0 P0 C0 
+	F000:FFF0 EA05F900F0    JMP      F000:F905
+	
+I want to catch writes to the top-left corner of the screen, so I set a write breakpoint:
+
+	bw b800:0
+
+which reports:
+
+	write breakpoint added to memory block 000B8000
+	breakpoint enabled: B800:0000 (write)
+
+and then we're off:
+
+	running
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x00) @F000:F907
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x01) @F000:F926
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x02) @F000:F93C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x03) @F000:F942
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x04) @F000:F946
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x05) @F000:F95F
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x06) @F000:F978
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x08) @F000:F9AA
+	notice: PIC0(0x20): unsupported OCW2 automatic EOI command: 0x00
+	stopped (149 ops, 622 cycles, 92 ms, 6761 hz)
+	EAX=0000F000 EBX=00000000 ECX=00000008 EDX=00000020 
+	ESP=00000000 EBP=00000000 ESI=0000F8E7 EDI=00000000 
+	SS=0000 DS=F000 ES=0000 FS=0000 GS=0304 PS=00000046 V0 D0 I0 T0 S0 Z1 A0 P1 C0 
+	F000:F9ED E6A0          OUT      A0,AL
+	running
+	notice: PIC1(0xA0): unsupported OCW2 automatic EOI command: 0x00
+	stopped (150 ops, 5 cycles, 19 ms, 263 hz)
+	EAX=0000F000 EBX=00000000 ECX=00000008 EDX=00000020 
+	ESP=00000000 EBP=00000000 ESI=0000F8E7 EDI=00000000 
+	SS=0000 DS=F000 ES=0000 FS=0000 GS=0304 PS=00000046 V0 D0 I0 T0 S0 Z1 A0 P1 C0 
+	F000:F9EF B009          MOV      AL,09
+	running
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x09) @F000:F9F1
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x0F) @F000:BAAA
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x10) @F000:BAFB
+	bus.outPort(0x004B,unknown,0x12) @F000:BAFF
+	bus.outPort(0x004B,unknown,0x42) @F000:BB03
+	bus.outPort(0x004B,unknown,0x92) @F000:BB07
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x11) @F000:BB29
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x12) @F000:BB70
+	breakpoint hit: B800:0000 (write)
+	stopped (413 ops, 959 cycles, 80 ms, 11988 hz)
+	EAX=00000720 EBX=0000BA77 ECX=00001FFF EDX=000003D8 
+	ESP=00000000 EBP=0000BB78 ESI=0000F0C6 EDI=00000002 
+	SS=0000 DS=F000 ES=B800 FS=0000 GS=0304 PS=00000046 V0 D0 I0 T0 S0 Z1 A0 P1 C0 
+	F000:9C05 F3            REPZ    
+	F000:9C06 AB            STOSW   
+
+This is where screen memory is first initialized ("blanked").
+
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x13) @F000:BB90
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x14) @F000:BBB8
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x15) @F000:BBD8
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x17) @F000:BC08
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x18) @F000:BC14
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x40) @F000:B552
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x2F) @0018:87B4
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x41) @F000:B572
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x42) @F000:B599
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x43) @F000:B5C4
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x44) @F000:B5D2
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x45) @F000:B600
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x43) @F000:B5C4
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x44) @F000:B5D2
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x45) @F000:B600
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x46) @F000:B61C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x19) @F000:BC2C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x30) @F000:A8B0
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x31) @F000:A905
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x32) @F000:A91D
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x33) @F000:A93B
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x34) @F000:A953
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x36) @F000:A991
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x38) @F000:A99C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x39) @F000:A9BC
+	bus.inPort(0x03BC,unknown) @F000:A9CA
+	bus.outPort(0x03BC,unknown,0x00) @F000:A9CD
+	bus.inPort(0x03BC,unknown) @F000:A9D0
+	bus.inPort(0x0378,unknown) @F000:A9CA
+	bus.outPort(0x0378,unknown,0x00) @F000:A9CD
+	bus.inPort(0x0378,unknown) @F000:A9D0
+	bus.inPort(0x0278,unknown) @F000:A9CA
+	bus.outPort(0x0278,unknown,0x00) @F000:A9CD
+	bus.inPort(0x0278,unknown) @F000:A9D0
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x3A) @F000:A9DE
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x3B) @F000:A9FB
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x52) @F000:AA41
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x53) @F000:AA54
+	bus.outPort(0x03B9,unknown,0x30) @F000:9BE7
+	write breakpoint added to memory block 000B8000
+	write breakpoint added to memory block 000B8000
+	breakpoint hit: B800:0000 (write)
+	stopped (1340834 ops, 3291994 cycles, 821 ms, 4009737 hz)
+	EAX=00000720 EBX=00000720 ECX=00003FFF EDX=0000B800 
+	ESP=000000D0 EBP=FFFF2230 ESI=00000CBA EDI=00000002 
+	SS=0030 DS=0000 ES=B800 FS=0000 GS=0304 PS=00000246 V0 D0 I1 T0 S0 Z1 A0 P1 C0 
+	C000:0E93 F3            REPZ    
+	C000:0E94 AB            STOSW   
+
+Now the video card's own BIOS is doing the same thing, followed by more of the same:
+
+	write breakpoint added to memory block 000B8000
+	write breakpoint added to memory block 000B8000
+	breakpoint hit: B800:0000 (write)
+	stopped (1384492 ops, 79242 cycles, 52 ms, 1523885 hz)
+	EAX=00000720 EBX=00000720 ECX=00003FFF EDX=0000B800 
+	ESP=000000C8 EBP=FFFF2230 ESI=00000C3A EDI=00000002 
+	SS=0030 DS=0000 ES=B800 FS=0000 GS=0304 PS=00000246 V0 D0 I1 T0 S0 Z1 A0 P1 C0 
+	C000:0E93 F3            REPZ    
+	C000:0E94 AB            STOSW   
+	running
+	breakpoint hit: B800:0000 (write)
+	stopped (1476959 ops, 347538 cycles, 67 ms, 5187134 hz)
+	EAX=00000FDB EBX=00000FDB ECX=00000050 EDX=000003DA 
+	ESP=000000CC EBP=FFFF00E2 ESI=00000000 EDI=00000002 
+	SS=0030 DS=0000 ES=B800 FS=0000 GS=0304 PS=00000246 V0 D0 I1 T0 S0 Z1 A0 P1 C0 
+	C000:18D7 FB            STI     
+	running
+	write breakpoint added to memory block 000B8000
+	write breakpoint added to memory block 000B8000
+	breakpoint hit: B800:0000 (write)
+	stopped (2824784 ops, 4644466 cycles, 528 ms, 8796337 hz)
+	EAX=00000720 EBX=00000720 ECX=00003FFF EDX=0000B800 
+	ESP=000000C8 EBP=FFFF2230 ESI=00000CBA EDI=00000002 
+	SS=0030 DS=0000 ES=B800 FS=0000 GS=0304 PS=00000246 V0 D0 I1 T0 S0 Z1 A0 P1 C0 
+	C000:0E93 F3            REPZ    
+	C000:0E94 AB            STOSW   
+	running
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x8C) @F000:D05C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x1A) @F000:BC79
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x50) @F000:AA76
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x51) @F000:AA7F
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x52) @F000:AA9C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x1B) @F000:BC80
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x1C) @F000:BC87
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x90) @F000:CC53
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x91) @F000:CC85
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x1D) @F000:BC8E
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x93) @F000:CC8A
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x94) @F000:CD06
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x95) @F000:CD3C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x96) @F000:CD6A
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x2D) @F000:BC95
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x0D) @F000:E107
+	bus.outPort(0x004B,unknown,0x12) @F000:E10B
+	bus.outPort(0x0048,unknown,0x22) @F000:E112
+	bus.outPort(0x004B,unknown,0x00) @F000:E139
+	bus.inPort(0x0048,unknown) @F000:E13B
+	bus.inPort(0x0048,unknown) @F000:E13E
+	bus.outPort(0x004B,unknown,0x12) @F000:E11A
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x0E) @F000:E11E
+	bus.outPort(0x004B,unknown,0x92) @F000:E122
+	bus.outPort(0x004A,unknown,0x22) @F000:E129
+	bus.outPort(0x004B,unknown,0x80) @F000:E139
+	bus.inPort(0x004A,unknown) @F000:E13B
+	bus.inPort(0x004A,unknown) @F000:E13E
+	bus.outPort(0x004B,unknown,0x92) @F000:E131
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x1E) @F000:BC9C
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x80) @F000:CFDF
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x81) @F000:CFF7
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x82) @F000:D011
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x84) @F000:D02D
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x1F) @F000:BCA3
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x75) @F000:F74D
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x76) @F000:F761
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x77) @0030:F772
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x78) @0030:F790
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x00) @F000:F907
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x07) @F000:F986
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x08) @F000:F9AA
+	notice: PIC0(0x20): unsupported OCW2 automatic EOI command: 0x00
+	stopped (19729382 ops, 81457037 cycles, 7165 ms, 11368742 hz)
+	EAX=0000F000 EBX=00000006 ECX=00000008 EDX=00000020 
+	ESP=00000000 EBP=00000000 ESI=0000F8E7 EDI=00000000 
+	SS=0000 DS=F000 ES=0000 FS=0000 GS=0000 PS=00000046 V0 D0 I0 T0 S0 Z1 A0 P1 C0 
+	F000:F9ED E6A0          OUT      A0,AL
+	running
+	notice: PIC1(0xA0): unsupported OCW2 automatic EOI command: 0x00
+	stopped (19729383 ops, 5 cycles, 20 ms, 250 hz)
+	EAX=0000F000 EBX=00000006 ECX=00000008 EDX=00000020 
+	ESP=00000000 EBP=00000000 ESI=0000F8E7 EDI=00000000 
+	SS=0000 DS=F000 ES=0000 FS=0000 GS=0000 PS=00000046 V0 D0 I0 T0 S0 Z1 A0 P1 C0 
+	F000:F9EF B009          MOV      AL,09
+
+We're back in the Compaq BIOS, the video card appears to be fully initialized now, so perhaps the next
+write to video memory will be the first memory test results.
+
+And in fact, it is. But the "bw b800:0" command doesn't work, because the memory test results are being
+performed in protected-mode, and there is no segment 0xB800 mapped to video memory at that point.
+
+So the write breakpoint must be specified as "bw %b8000" instead.  Now we catch it:
+
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x09) @F000:F9F1
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x79) @F000:F7CD
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x7B) @F000:F814
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x20) @F000:BCAA
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x60) @F000:D6E6
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x61) @F000:D704
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x18) @0030:870A
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x18) @0030:8715
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x62) @0030:D719
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x63) @0030:D761
+	chipset.outPort(0x0084,DMA.SPARE0.PAGE,0x70) @0030:DB38
+	breakpoint hit: %000B8000 (write)
+	stopped (19736120 ops, 23810 cycles, 165 ms, 144303 hz)
+	EAX=00000000 EBX=0000000A ECX=0000000A EDX=00000730 
+	ESP=000000D0 EBP=00000080 ESI=00000095 EDI=00008002 
+	SS=0028[00000300,FFFF] DS=0018[0001C000,FFFF] ES=0040[000B0000,FFFF] 
+	CS=0030[000F0000,FFFF] FS=0000[00000000,FFFF] GS=0304[00003040,FFFF]
+	LD=0000[00000000,0000] GD=[0001C000,005F] ID=[000FF821,0007] TR=0000 A20=ON 
+	CR0=0000FFF1 CR2=00000000 CR3=00000000 PS=00000082 V0 D0 I0 T0 S1 Z0 A0 P0 C0 
+	0030:80DA F3            REPZ    
+	0030:80DB A5            MOVSW   
+
diff --git a/devices/pc/machine/compaq/deskpro386/ega/2048kb/machine.xml b/devices/pc/machine/compaq/deskpro386/ega/2048kb/machine.xml
index 2a9060bb7..99be534f1 100644
--- a/devices/pc/machine/compaq/deskpro386/ega/2048kb/machine.xml
+++ b/devices/pc/machine/compaq/deskpro386/ega/2048kb/machine.xml
@@ -10,7 +10,7 @@
 	<rom id="romBIOS" addr="0xf8000" size="0x8000" alias="[0xf0000,0xffff0000,0xffff8000]" file="/devices/pc/bios/compaq/deskpro386/1988-01-28.json"/>
 	<video ref="/devices/pc/video/video-ega-128kb-lock.xml"/>
 	<keyboard ref="/devices/pc/keyboard/keyboard-minimal-functions.xml"/>
-	<debugger id="debugger" messages="fault" commands=""/>
+	<debugger id="debugger" messages="fault|port" commands=""/>
 	<panel ref="/devices/pc/panel/btpanel.xml"/>
 	<fdc ref="/disks/pc/library.xml" width="340px" automount='{A: {name: "PC-DOS 3.00 (Disk 1)", path: "/disks/pc/dos/ibm/3.00/PCDOS300-DISK1.json"}, B: {name: "PC-DOS 3.00 (Disk 2)", path: "/disks/pc/dos/ibm/3.00/PCDOS300-DISK2.json"}}'/>
 	<hdc id="hdcAT" type="at" drives='[{name:"20Mb Hard Disk",type:2}]'/>
diff --git a/modules/pcjs/lib/chipset.js b/modules/pcjs/lib/chipset.js
index 84be23307..cfdc7ab6a 100644
--- a/modules/pcjs/lib/chipset.js
+++ b/modules/pcjs/lib/chipset.js
@@ -326,7 +326,7 @@ ChipSet.aMonitorSwitches = {
  *  For FDC DMA notes, refer to http://wiki.osdev.org/ISA_DMA
  *  For general DMA notes, refer to http://www.freebsd.org/doc/en/books/developers-handbook/dma.html
  *
- *  TODO: Determine why the MODEL_5150 ROM BIOS sets the page register for channel 1 (port 0x83) to zero
+ *  TODO: Determine why the MODEL_5150 ROM BIOS sets the DMA channel 1 page register (port 0x83) to zero
  */
 ChipSet.DMA0 = {
     INDEX:              0,
@@ -359,7 +359,7 @@ ChipSet.DMA1 = {
         CH6_PAGE:       0x89,   // OUT: DMA channel 6 page register (MODEL_5170)
         CH7_PAGE:       0x8A,   // OUT: DMA channel 7 page register (MODEL_5170)
         CH5_PAGE:       0x8B,   // OUT: DMA channel 5 page register (MODEL_5170)
-        CH4_PAGE:       0x8F,   // OUT: DMA channel 4 page register (MODEL_5170; unusable; aka "refresh" page register?)
+        CH4_PAGE:       0x8F,   // OUT: DMA channel 4 page register (MODEL_5170; unusable; aka "Refresh" page register?)
         CH4_ADDR:       0xC0,   // OUT: starting address        IN: current address
         CH4_COUNT:      0xC2,   // OUT: starting word count     IN: remaining word count
         CH5_ADDR:       0xC4,   // OUT: starting address        IN: current address
@@ -890,22 +890,54 @@ ChipSet.CMOS = {
 };
 
 /*
- * Manufacturing Test Ports (MODEL_5170)
+ * DMA Page Registers
  *
- * The MODEL_5170 TechRef lists 0x80-0x9F as the range for DMA page registers, but that seems a bit
- * overbroad; at one point, it says:
+ * The MODEL_5170 TechRef lists 0x80-0x9F as the range for DMA page registers, but that may be a bit
+ * overbroad.  There are a total of 8 (7 usable) DMA channels on the MODEL_5170, each of which has the
+ * following assigned DMA page registers:
+ *
+ *      Channel #   Page Reg
+ *      ---------   --------
+ *          0         0x87
+ *          1         0x83
+ *          2         0x81
+ *          3         0x82
+ *          4         0x8F (not usable; the 5170 TechRef refers to this as the "Refresh" page register)
+ *          5         0x8B
+ *          6         0x89
+ *          7         0x8A
+ *
+ * That leaves 0x80, 0x84, 0x85, 0x86, 0x88, 0x8C, 0x8D and 0x8E unaccounted for in the range 0x80-0x8F.
+ * (I'm saving the question of what, if anything, is available in the range 0x90-0x9F for another day.)
+ *
+ * As for port 0x80, the TechRef says:
  *
  *      "I/O address hex 080 is used as a diagnostic-checkpoint port or register.
- *      This port corresponds to a read/write register in the DMA page register (74LS6I2)."
+ *      This port corresponds to a read/write register in the DMA page register (74LS612)."
  *
- * 0x80 is the neighborhood, but that particular port is not documented as a DMA page register.
- * We'll refer to it as a "manufacturing port" (see bMFGData).  Be aware that the MODEL_5170 BIOS is
- * littered with manufacturing test ("MFG_TST") code which, if enabled, writes to other DMA page
- * registers, presumably treating them as scratch registers.
+ * so I used to have dedicated handlers and storage (bMFGData) for the register at port 0x80, but I've since
+ * appended it to abDMAPageSpare, an 8-element array that captures all I/O to the 8 unassigned (aka "spare")
+ * DMA page registers.  The 5170 BIOS uses 0x80 as a "checkpoint" register, and the DESKPRO386 uses 0x84 in a
+ * similar fashion.  The 5170 also contains "MFG_TST" code that uses other unassigned DMA page registers as
+ * scratch registers, which come in handy when RAM hasn't been tested/initialized yet.
+ *
+ * Here's our mapping of entries in the abDMAPageSpare array to the unassigned ("spare") DMA page registers:
+ *
+ *      Index #     Page Reg
+ *      --------    --------
+ *          0         0x84
+ *          1         0x85
+ *          2         0x86
+ *          3         0x88
+ *          4         0x8C
+ *          5         0x8D
+ *          6         0x8E
+ *          7         0x80
+ *
+ * The only reason port 0x80 is out of sequence (ie, at the end of the array, at index 7 instead of index 0) is
+ * because it was added the array later, and the entire array gets written to our save/restore data structures, so
+ * reordering the elements would be a bad idea.
  */
-ChipSet.MFG = {                 // this.bMFGData
-    PORT:               0x80
-};
 
 /*
  * NMI Mask Register (MODEL_5150 and MODEL_5160 only)
@@ -1125,8 +1157,7 @@ ChipSet.prototype.reset = function(fHard)
 
         this.b8042OutPort = ChipSet.KBC.OUTPORT.NO_RESET | ChipSet.KBC.OUTPORT.A20_ON;
 
-        this.bMFGData = 0;
-        this.abDMAPageSpare = new Array(7);
+        this.abDMAPageSpare = new Array(8);
 
         this.bCMOSAddr = 0;         // NMI is enabled, since the ChipSet.CMOS.ADDR.NMI_DISABLE bit is not set in bCMOSAddr
 
@@ -1679,7 +1710,7 @@ ChipSet.prototype.save = function()
     if (this.model >= ChipSet.MODEL_5170) {
         state.set(5, [this.b8042Status, this.b8042InBuff, this.b8042CmdData,
                       this.b8042OutBuff, this.b8042InPort, this.b8042OutPort]);
-        state.set(6, [this.bMFGData, this.abDMAPageSpare, this.bCMOSAddr, this.abCMOSData, this.nRTCCyclesLastUpdate, this.nRTCCyclesNextUpdate]);
+        state.set(6, [this.abDMAPageSpare[7], this.abDMAPageSpare, this.bCMOSAddr, this.abCMOSData, this.nRTCCyclesLastUpdate, this.nRTCCyclesNextUpdate]);
     }
     return state.data();
 };
@@ -1739,8 +1770,8 @@ ChipSet.prototype.restore = function(data)
     a = data[6];
     if (a) {
         this.assert(this.model >= ChipSet.MODEL_5170);
-        this.bMFGData = a[0];
         this.abDMAPageSpare = a[1];
+        this.abDMAPageSpare[7] = a[0];  // formerly bMFGData
         this.bCMOSAddr = a[2];
         this.abCMOSData = a[3];
         this.nRTCCyclesLastUpdate = a[4];
@@ -2675,7 +2706,11 @@ ChipSet.prototype.inDMAPageSpare = function(iSpare, port, addrFrom)
  */
 ChipSet.prototype.outDMAPageSpare = function(iSpare, port, bOut, addrFrom)
 {
-    if (this.messageEnabled(Messages.DMA | Messages.PORT)) {
+    /*
+     * TODO: Remove the DEBUG-only DESKPRO386 code once we're done debugging DeskPro 386 ROMs;
+     * it enables logging of all DeskPro ROM checkpoint I/O to port 0x84.
+     */
+    if (this.messageEnabled(Messages.DMA | Messages.PORT) || DEBUG && this.model == ChipSet.MODEL_DESKPRO386 && port == 0x84) {
         this.printMessageIO(port, bOut, addrFrom, "DMA.SPARE" + iSpare + ".PAGE", null, true);
     }
     this.abDMAPageSpare[iSpare] = bOut;
@@ -4680,34 +4715,6 @@ ChipSet.prototype.outCMOSData = function(port, bOut, addrFrom)
     }
 };
 
-/**
- * inMFGData(port, addrFrom)
- *
- * @this {ChipSet}
- * @param {number} port (0x80)
- * @param {number} [addrFrom] (not defined if the Debugger is trying to read the specified port)
- * @return {number} simulated port value
- */
-ChipSet.prototype.inMFGData = function(port, addrFrom)
-{
-    this.printMessageIO(port, null, addrFrom, "MFG_DATA", this.bMFGData);
-    return this.bMFGData;
-};
-
-/**
- * outMFGData(port, bOut, addrFrom)
- *
- * @this {ChipSet}
- * @param {number} port (0x80)
- * @param {number} bOut
- * @param {number} [addrFrom] (not defined if the Debugger is trying to write the specified port)
- */
-ChipSet.prototype.outMFGData = function(port, bOut, addrFrom)
-{
-    this.printMessageIO(port, bOut, addrFrom, "MFG_DATA");
-    this.bMFGData = bOut;
-};
-
 /**
  * outNMI(port, bOut, addrFrom)
  *
@@ -4985,7 +4992,7 @@ ChipSet.aPortInput5170 = {
     0x64: ChipSet.prototype.in8042Status,
     0x70: ChipSet.prototype.inCMOSAddr,
     0x71: ChipSet.prototype.inCMOSData,
-    0x80: ChipSet.prototype.inMFGData,
+    0x80: /** @this {ChipSet} */ function(port, addrFrom) { return this.inDMAPageSpare(7, port, addrFrom); },
     0x84: /** @this {ChipSet} */ function(port, addrFrom) { return this.inDMAPageSpare(0, port, addrFrom); },
     0x85: /** @this {ChipSet} */ function(port, addrFrom) { return this.inDMAPageSpare(1, port, addrFrom); },
     0x86: /** @this {ChipSet} */ function(port, addrFrom) { return this.inDMAPageSpare(2, port, addrFrom); },
@@ -5054,7 +5061,7 @@ ChipSet.aPortOutput5170 = {
     0x64: ChipSet.prototype.out8042InBuffCmd,
     0x70: ChipSet.prototype.outCMOSAddr,
     0x71: ChipSet.prototype.outCMOSData,
-    0x80: ChipSet.prototype.outMFGData,
+    0x80: /** @this {ChipSet} */ function(port, bOut, addrFrom) { this.outDMAPageSpare(7, port, bOut, addrFrom); },
     0x84: /** @this {ChipSet} */ function(port, bOut, addrFrom) { this.outDMAPageSpare(0, port, bOut, addrFrom); },
     0x85: /** @this {ChipSet} */ function(port, bOut, addrFrom) { this.outDMAPageSpare(1, port, bOut, addrFrom); },
     0x86: /** @this {ChipSet} */ function(port, bOut, addrFrom) { this.outDMAPageSpare(2, port, bOut, addrFrom); },
diff --git a/modules/pcjs/lib/computer.js b/modules/pcjs/lib/computer.js
index fbccbe769..50b2a72ed 100644
--- a/modules/pcjs/lib/computer.js
+++ b/modules/pcjs/lib/computer.js
@@ -876,6 +876,10 @@ Computer.prototype.powerOff = function(fSave, fShutdown)
 Computer.prototype.reset = function()
 {
     if (this.bus && this.bus.reset) {
+        /*
+         * TODO: Why does WebStorm think that this.bus.type is undefined? The base class (Component)
+         * constructor defines it.
+         */
         this.printMessage("Resetting " + this.bus.type);
         this.bus.reset();
     }
diff --git a/modules/pcjs/lib/debugger.js b/modules/pcjs/lib/debugger.js
index 1ee00ab19..3698aff97 100644
--- a/modules/pcjs/lib/debugger.js
+++ b/modules/pcjs/lib/debugger.js
@@ -2549,7 +2549,7 @@ if (DEBUGGER) {
      * @this {Debugger}
      * @param {Array} aAddr
      * @param {boolean} [fWrite]
-     * @param {number} [cb] is number of extra bytes to check (0, 1 or 3)
+     * @param {number} [cb] is number of bytes to check (1, 2 or 4); default is 1
      * @return {number} is the corresponding physical address, or X86.ADDR_INVALID
      */
     Debugger.prototype.getAddr = function(aAddr, fWrite, cb)
@@ -2564,9 +2564,9 @@ if (DEBUGGER) {
         if (addr == null) {
             var seg = this.getSegment(aAddr[1]);
             if (!fWrite) {
-                addr = seg.checkRead(aAddr[0], cb || 0, true);
+                addr = seg.checkRead(aAddr[0], cb || 1, true);
             } else {
-                addr = seg.checkWrite(aAddr[0], cb || 0, true);
+                addr = seg.checkWrite(aAddr[0], cb || 1, true);
             }
             aAddr[2] = addr;
         }
@@ -2587,7 +2587,7 @@ if (DEBUGGER) {
     Debugger.prototype.getByte = function(aAddr, inc)
     {
         var b = 0xff;
-        var addr = this.getAddr(aAddr, false, 0);
+        var addr = this.getAddr(aAddr, false, 1);
         if (addr !== X86.ADDR_INVALID) {
             b = this.bus.getByteDirect(addr);
             this.assert((b == (b & 0xff)), "invalid byte (" + b + ") at address: " + this.hexAddr(aAddr));
@@ -2623,7 +2623,7 @@ if (DEBUGGER) {
     Debugger.prototype.getShort = function(aAddr, inc)
     {
         var w = 0xffff;
-        var addr = this.getAddr(aAddr, false, 1);
+        var addr = this.getAddr(aAddr, false, 2);
         if (addr !== X86.ADDR_INVALID) {
             w = this.bus.getShortDirect(addr);
             this.assert((w == (w & 0xffff)), "invalid word (" + w + ") at address: " + this.hexAddr(aAddr));
@@ -2643,7 +2643,7 @@ if (DEBUGGER) {
     Debugger.prototype.getLong = function(aAddr, inc)
     {
         var l = -1;
-        var addr = this.getAddr(aAddr, false, 3);
+        var addr = this.getAddr(aAddr, false, 4);
         if (addr !== X86.ADDR_INVALID) {
             l = this.bus.getLongDirect(addr);
             if (inc !== undefined) this.incAddr(aAddr, inc);
@@ -2665,7 +2665,7 @@ if (DEBUGGER) {
      */
     Debugger.prototype.setByte = function(aAddr, b, inc)
     {
-        var addr = this.getAddr(aAddr, true, 0);
+        var addr = this.getAddr(aAddr, true, 1);
         if (addr !== X86.ADDR_INVALID) {
             this.bus.setByteDirect(addr, b);
             if (inc !== undefined) this.incAddr(aAddr, inc);
@@ -2683,7 +2683,7 @@ if (DEBUGGER) {
      */
     Debugger.prototype.setShort = function(aAddr, w, inc)
     {
-        var addr = this.getAddr(aAddr, true, 1);
+        var addr = this.getAddr(aAddr, true, 2);
         if (addr !== X86.ADDR_INVALID) {
             this.bus.setShortDirect(addr, w);
             if (inc !== undefined) this.incAddr(aAddr, inc);
diff --git a/modules/pcjs/lib/ram.js b/modules/pcjs/lib/ram.js
index c01fe14ef..74adcc153 100644
--- a/modules/pcjs/lib/ram.js
+++ b/modules/pcjs/lib/ram.js
@@ -166,7 +166,7 @@ RAM.prototype.reset = function()
         if (this.bus.addMemory(this.addrRAM, this.sizeRAM, Memory.TYPE.RAM)) {
             this.fAllocated = true;
 
-            this.status(Math.floor(this.sizeRAM / 1024) + "Kb");
+            this.status(Math.floor(this.sizeRAM / 1024) + "Kb allocated");
 
             /*
              * NOTE: I'm specifying MAXDEBUG for status() messages because I'm not yet sure I want these
@@ -175,6 +175,7 @@ RAM.prototype.reset = function()
              * for these components, which the Computer component will display as it "powers up" components.
              */
             if (MAXDEBUG && this.fInstalled) this.status("specified size overrides SW1");
+
             /*
              * Memory with an ID of "ramCPQ" is reserved for built-in memory located just below the 16Mb
              * boundary on Compaq DeskPro 386 machines.
diff --git a/modules/pcjs/lib/serialport.js b/modules/pcjs/lib/serialport.js
index d3eeb682b..118224962 100644
--- a/modules/pcjs/lib/serialport.js
+++ b/modules/pcjs/lib/serialport.js
@@ -67,17 +67,17 @@ function SerialPort(parmsSerial) {
     this.iAdapter = parmsSerial['adapter'];
 
     switch (this.iAdapter) {
-        case 1:
-            this.portBase = 0x3F8;
-            this.nIRQ = ChipSet.IRQ.COM1;
-            break;
-        case 2:
-            this.portBase = 0x2F8;
-            this.nIRQ = ChipSet.IRQ.COM2;
-            break;
-        default:
-            Component.warning("Unrecognized serial adapter #" + this.iAdapter);
-            return;
+    case 1:
+        this.portBase = 0x3F8;
+        this.nIRQ = ChipSet.IRQ.COM1;
+        break;
+    case 2:
+        this.portBase = 0x2F8;
+        this.nIRQ = ChipSet.IRQ.COM2;
+        break;
+    default:
+        Component.warning("Unrecognized serial adapter #" + this.iAdapter);
+        return;
     }
 
     /**
@@ -322,6 +322,7 @@ SerialPort.prototype.syncMouse = function()
 SerialPort.prototype.setBinding = function(sHTMLType, sBinding, control)
 {
     var serial = this;
+
     switch (sBinding) {
     case SerialPort.sIOBuffer:
         this.bindings[sBinding] = this.controlIOBuffer = control;
diff --git a/modules/pcjs/lib/video.js b/modules/pcjs/lib/video.js
index 020a0a067..cea9e2968 100644
--- a/modules/pcjs/lib/video.js
+++ b/modules/pcjs/lib/video.js
@@ -1249,7 +1249,7 @@ Card.ACCESS.WRITE.MASK      = 0xff00;
  */
 Card.ACCESS.readShort = function readShort(off)
 {
-    return this.readByte(off) | (this.readByte(off + 1) << 8);
+    return this.readByteDirect(off) | (this.readByteDirect(off + 1) << 8);
 };
 
 /**
@@ -1261,7 +1261,7 @@ Card.ACCESS.readShort = function readShort(off)
  */
 Card.ACCESS.readLong = function readLong(off)
 {
-    return this.readByte(off) | (this.readByte(off + 1) << 8) | (this.readByte(off + 2) << 16) | (this.readByte(off + 3) << 24);
+    return this.readByteDirect(off) | (this.readByteDirect(off + 1) << 8) | (this.readByteDirect(off + 2) << 16) | (this.readByteDirect(off + 3) << 24);
 };
 
 /**
@@ -1274,8 +1274,8 @@ Card.ACCESS.readLong = function readLong(off)
 Card.ACCESS.writeShort = function writeShort(off, w)
 {
     Component.assert(!(w & ~0xffff));
-    this.writeByte(off, w & 0xff);
-    this.writeByte(off + 1, w >> 8);
+    this.writeByteDirect(off, w & 0xff);
+    this.writeByteDirect(off + 1, w >> 8);
 };
 
 /**
@@ -1287,10 +1287,10 @@ Card.ACCESS.writeShort = function writeShort(off, w)
  */
 Card.ACCESS.writeLong = function writeLong(off, w)
 {
-    this.writeByte(off, w & 0xff);
-    this.writeByte(off + 1, (w >> 8) & 0xff);
-    this.writeByte(off + 2, (w >> 16) & 0xff);
-    this.writeByte(off + 3, (w >>> 24));
+    this.writeByteDirect(off, w & 0xff);
+    this.writeByteDirect(off + 1, (w >> 8) & 0xff);
+    this.writeByteDirect(off + 2, (w >> 16) & 0xff);
+    this.writeByteDirect(off + 3, (w >>> 24));
 };
 
 /**
diff --git a/modules/pcjs/lib/x86cpu.js b/modules/pcjs/lib/x86cpu.js
index 91425042c..e20b7b04a 100644
--- a/modules/pcjs/lib/x86cpu.js
+++ b/modules/pcjs/lib/x86cpu.js
@@ -1386,8 +1386,8 @@ X86CPU.prototype.setProtMode = function(fProt)
     if (fProt === undefined) {
         fProt = !!(this.regCR0 & X86.CR0.MSW.PE);
     }
-    if (!fProt) {
-        this.printMessage("returning to real-mode");
+    if (!fProt != !(this.regCR0 & X86.CR0.MSW.PE)) {
+        this.printMessage("CPU switching to " + (fProt? "protected" : "real") + "-mode", this.bitsMessage, true);
     }
     this.aOpGrp6 = (fProt? X86.aOpGrp6Prot : X86.aOpGrp6Real);
     this.segCS.updateMode(fProt);
@@ -2650,7 +2650,7 @@ X86CPU.prototype.setLong = function(addr, l)
 X86CPU.prototype.getEAByte = function(seg, off)
 {
     this.segEA = seg;
-    this.regEA = seg.checkRead(this.offEA = off, 0);
+    this.regEA = seg.checkRead(this.offEA = off, 1);
     if (this.opFlags & X86.OPFLAG.NOREAD) return 0;
     var b = this.getByte(this.regEA);
     if (BACKTRACK) this.backTrack.btiEALo = this.backTrack.btiMemLo;
@@ -2692,7 +2692,7 @@ X86CPU.prototype.getEAByteStack = function(off)
 X86CPU.prototype.getEAWord = function(seg, off)
 {
     this.segEA = seg;
-    this.regEA = seg.checkRead(this.offEA = off, (I386? this.dataSize-1 : 1));
+    this.regEA = seg.checkRead(this.offEA = off, (I386? this.dataSize : 2));
     if (this.opFlags & X86.OPFLAG.NOREAD) return 0;
     var w = this.getWord(this.regEA);
     if (BACKTRACK) {
@@ -2737,7 +2737,7 @@ X86CPU.prototype.getEAWordStack = function(off)
 X86CPU.prototype.modEAByte = function(seg, off)
 {
     this.segEA = seg;
-    this.regEAWrite = this.regEA = seg.checkRead(this.offEA = off, 0);
+    this.regEAWrite = this.regEA = seg.checkRead(this.offEA = off, 1);
     if (this.opFlags & X86.OPFLAG.NOREAD) return 0;
     var b = this.getByte(this.regEA);
     if (BACKTRACK) this.backTrack.btiEALo = this.backTrack.btiMemLo;
@@ -2779,7 +2779,7 @@ X86CPU.prototype.modEAByteStack = function(off)
 X86CPU.prototype.modEAWord = function(seg, off)
 {
     this.segEA = seg;
-    this.regEAWrite = this.regEA = seg.checkRead(this.offEA = off, (I386? this.dataSize-1 : 1));
+    this.regEAWrite = this.regEA = seg.checkRead(this.offEA = off, (I386? this.dataSize : 2));
     if (this.opFlags & X86.OPFLAG.NOREAD) return 0;
     var w = this.getWord(this.regEA);
     if (BACKTRACK) {
@@ -2823,7 +2823,7 @@ X86CPU.prototype.setEAByte = function(b)
 {
     if (this.opFlags & X86.OPFLAG.NOWRITE) return;
     if (BACKTRACK) this.backTrack.btiMemLo = this.backTrack.btiEALo;
-    this.setByte(this.segEA.checkWrite(this.offEA, 0), b);
+    this.setByte(this.segEA.checkWrite(this.offEA, 1), b);
 };
 
 /**
@@ -2840,9 +2840,9 @@ X86CPU.prototype.setEAWord = function(w)
         this.backTrack.btiMemHi = this.backTrack.btiEAHi;
     }
     if (!I386) {
-        this.setShort(this.segEA.checkWrite(this.offEA, 1), w);
+        this.setShort(this.segEA.checkWrite(this.offEA, 2), w);
     } else {
-        this.setWord(this.segEA.checkWrite(this.offEA, this.dataSize-1), w);
+        this.setWord(this.segEA.checkWrite(this.offEA, this.dataSize), w);
     }
 };
 
@@ -2858,7 +2858,7 @@ X86CPU.prototype.setEAWord = function(w)
  */
 X86CPU.prototype.getSOByte = function(seg, off)
  {
-    return this.getByte(seg.checkRead(off, 0));
+    return this.getByte(seg.checkRead(off, 1));
 };
 
 /**
@@ -2874,9 +2874,9 @@ X86CPU.prototype.getSOByte = function(seg, off)
 X86CPU.prototype.getSOWord = function(seg, off)
 {
     if (!I386) {
-        return this.getShort(seg.checkRead(off, 1));
+        return this.getShort(seg.checkRead(off, 2));
     } else {
-        return this.getWord(seg.checkRead(off, this.dataSize-1));
+        return this.getWord(seg.checkRead(off, this.dataSize));
     }
 };
 
@@ -2892,7 +2892,7 @@ X86CPU.prototype.getSOWord = function(seg, off)
  */
 X86CPU.prototype.setSOByte = function(seg, off, b)
 {
-    this.setByte(seg.checkWrite(off, 0), b);
+    this.setByte(seg.checkWrite(off, 1), b);
 };
 
 /**
@@ -2908,9 +2908,9 @@ X86CPU.prototype.setSOByte = function(seg, off, b)
 X86CPU.prototype.setSOWord = function(seg, off, w)
 {
     if (!I386) {
-        this.setShort(seg.checkWrite(off, 1), w);
+        this.setShort(seg.checkWrite(off, 2), w);
     } else {
-        this.setWord(seg.checkWrite(off, this.dataSize-1), w);
+        this.setWord(seg.checkWrite(off, this.dataSize), w);
     }
 };
 
diff --git a/modules/pcjs/lib/x86func.js b/modules/pcjs/lib/x86func.js
index 21d8facfc..77e461401 100644
--- a/modules/pcjs/lib/x86func.js
+++ b/modules/pcjs/lib/x86func.js
@@ -33,6 +33,7 @@
 "use strict";
 
 if (typeof module !== 'undefined') {
+    var str         = require("../../shared/lib/strlib");
     var Messages    = require("./messages");
     var X86         = require("./x86");
 }
@@ -172,8 +173,8 @@ X86.fnBOUND = function BOUND(dst, src)
      * Note that BOUND performs signed comparisons, so we must transform all arguments into signed values.
      */
     var wIndex = (dst << 16) >> 16;
-    var wLower = (this.getShort(this.regEA) << 16) >> 16;
-    var wUpper = (this.getShort(this.regEA + 2) << 16) >> 16;
+    var wLower = (this.getWord(this.regEA) << 16) >> 16;
+    var wUpper = (this.getWord(this.regEA + this.dataSize) << 16) >> 16;
     this.nStepCycles -= this.cycleCounts.nOpCyclesBound;
     if (wIndex < wLower || wIndex > wUpper) {
         /*
@@ -332,6 +333,7 @@ X86.fnBTS = function BTS(dst, src)
  */
 X86.fnCALLw = function CALLw(dst, src)
 {
+    if (DEBUG) this.printMessage("calling " + str.toHex(dst, this.dataSize << 1), this.bitsMessage, true);
     this.pushWord(this.getIP());
     this.setIP(dst);
     this.nStepCycles -= (this.regEA === X86.ADDR_INVALID? this.cycleCounts.nOpCyclesCallWR : this.cycleCounts.nOpCyclesCallWM);
@@ -351,11 +353,12 @@ X86.fnCALLw = function CALLw(dst, src)
  */
 X86.fnCALLF = function CALLF(off, sel)
 {
-    var regCS = this.getCS();
-    var regEIP = this.getIP();
+    if (DEBUG) this.printMessage("calling " + str.toHex(sel, 4) + ':' + str.toHex(off, this.dataSize << 1), this.bitsMessage, true);
+    var oldCS = this.getCS();
+    var oldIP = this.getIP();
     if (this.setCSIP(off, sel, true) != null) {
-        this.pushWord(regCS);
-        this.pushWord(regEIP);
+        this.pushWord(oldCS);
+        this.pushWord(oldIP);
     }
 };
 
@@ -372,7 +375,7 @@ X86.fnCALLFdw = function CALLFdw(dst, src)
     if (this.regEA === X86.ADDR_INVALID) {
         return X86.fnGRPUndefined.call(this, dst, src);
     }
-    X86.fnCALLF.call(this, dst, this.getShort(this.regEA + 2));
+    X86.fnCALLF.call(this, dst, this.getShort(this.regEA + this.dataSize));
     this.nStepCycles -= this.cycleCounts.nOpCyclesCallDM;
     this.opFlags |= X86.OPFLAG.NOWRITE;
     return dst;
@@ -917,16 +920,16 @@ X86.fnINT = function INT(nIDT, nError, nCycles)
      */
     this.nStepCycles -= this.cycleCounts.nOpCyclesInt + nCycles;
     this.segCS.fCall = true;
-    var regPS = this.getPS();
-    var regCS = this.getCS();
-    var regEIP = this.getIP();
+    var oldPS = this.getPS();
+    var oldCS = this.getCS();
+    var oldIP = this.getIP();
     var addr = this.segCS.loadIDT(nIDT);
     if (addr != X86.ADDR_INVALID) {
         this.regLIP = addr;
         if (PREFETCH) this.flushPrefetch(this.regLIP);
-        this.pushWord(regPS);
-        this.pushWord(regCS);
-        this.pushWord(regEIP);
+        this.pushWord(oldPS);
+        this.pushWord(oldCS);
+        this.pushWord(oldIP);
         if (nError != null) this.pushWord(nError);
         this.nFault = -1;
     }
@@ -952,11 +955,12 @@ X86.fnIRET = function IRET()
         }
     }
     var cpl = this.segCS.cpl;
-    var regEIP = this.popWord();
-    var regCS  = this.popWord();
-    var regPS  = this.popWord();
-    if (this.setCSIP(regEIP, regCS, false) != null) {
-        this.setPS(regPS, cpl);
+    var newIP = this.popWord();
+    var newCS = this.popWord();
+    var newPS = this.popWord();
+    if (DEBUG) this.printMessage(" returning to " + str.toHex(newCS, 4) + ':' + str.toHex(newIP, this.dataSize << 1), this.bitsMessage, true);
+    if (this.setCSIP(newIP, newCS, false) != null) {
+        this.setPS(newPS, cpl);
         if (this.cIntReturn) this.checkIntReturn(this.regLIP);
     }
 };
@@ -990,7 +994,7 @@ X86.fnJMPFdw = function JMPFdw(dst, src)
     if (this.regEA === X86.ADDR_INVALID) {
         return X86.fnGRPUndefined.call(this, dst, src);
     }
-    this.setCSIP(dst, this.getShort(this.regEA + 2));
+    this.setCSIP(dst, this.getShort(this.regEA + this.dataSize));
     if (this.cIntReturn) this.checkIntReturn(this.regLIP);
     this.nStepCycles -= this.cycleCounts.nOpCyclesJmpDM;
     this.opFlags |= X86.OPFLAG.NOWRITE;
@@ -1055,7 +1059,7 @@ X86.fnLDS = function LDS(dst, src)
         X86.opUndefined.call(this);
         return dst;
     }
-    this.setDS(this.getShort(this.regEA + 2));
+    this.setDS(this.getShort(this.regEA + this.dataSize));
     this.nStepCycles -= this.cycleCounts.nOpCyclesLS;
     return src;
 };
@@ -1101,7 +1105,7 @@ X86.fnLES = function LES(dst, src)
         X86.opUndefined.call(this);
         return dst;
     }
-    this.setES(this.getShort(this.regEA + 2));
+    this.setES(this.getShort(this.regEA + this.dataSize));
     this.nStepCycles -= this.cycleCounts.nOpCyclesLS;
     return src;
 };
@@ -1120,7 +1124,7 @@ X86.fnLFS = function LFS(dst, src)
         X86.opUndefined.call(this);
         return dst;
     }
-    this.setFS(this.getShort(this.regEA + 2));
+    this.setFS(this.getShort(this.regEA + this.dataSize));
     this.nStepCycles -= this.cycleCounts.nOpCyclesLS;
     return src;
 };
@@ -1170,7 +1174,7 @@ X86.fnLGS = function LGS(dst, src)
         X86.opUndefined.call(this);
         return dst;
     }
-    this.setGS(this.getShort(this.regEA + 2));
+    this.setGS(this.getShort(this.regEA + this.dataSize));
     this.nStepCycles -= this.cycleCounts.nOpCyclesLS;
     return src;
 };
@@ -1287,7 +1291,7 @@ X86.fnLSS = function LSS(dst, src)
         X86.opUndefined.call(this);
         return dst;
     }
-    this.setSS(this.getShort(this.regEA + 2));
+    this.setSS(this.getShort(this.regEA + this.dataSize));
     this.nStepCycles -= this.cycleCounts.nOpCyclesLS;
     return src;
 };
@@ -1738,11 +1742,12 @@ X86.fnRCRd = function RCRd(dst, src)
  */
 X86.fnRETF = function RETF(n)
 {
-    var regEIP = this.popWord();
-    var regCS = this.popWord();
+    var newIP = this.popWord();
+    var newCS = this.popWord();
+    if (DEBUG) this.printMessage(" returning to " + str.toHex(newCS, 4) + ':' + str.toHex(newIP, this.dataSize << 1), this.bitsMessage, true);
     n <<= (this.dataSize >> 2);
     if (n) this.setSP(this.getSP() + n);            // TODO: optimize
-    if (this.setCSIP(regEIP, regCS, false)) {
+    if (this.setCSIP(newIP, newCS, false)) {
         if (n) this.setSP(this.getSP() + n);        // TODO: optimize
         /*
          * As per Intel documentation: "If any of [the DS or ES] registers refer to segments whose DPL is
diff --git a/modules/pcjs/lib/x86ops.js b/modules/pcjs/lib/x86ops.js
index 9750fa656..3ce6b884d 100644
--- a/modules/pcjs/lib/x86ops.js
+++ b/modules/pcjs/lib/x86ops.js
@@ -33,6 +33,7 @@
 "use strict";
 
 if (typeof module !== 'undefined') {
+    var str         = require("../../shared/lib/strlib");
     var Component   = require("../../shared/lib/component");
     var Messages    = require("./messages");
     var X86         = require("./x86");
@@ -1562,8 +1563,7 @@ X86.opOUTSb = function OUTSb()
 
     /*
      * NOTE: 5 + 4n is the cycle time for the 80286; the 80186/80188 has different values: 14 cycles for
-     * an unrepeated INS, and 8 + 8n for a repeated INS.  However, accurate cycle times for the 80186/80188 is
-     * low priority. TODO: Fix this someday.
+     * an unrepeated INS, and 8 + 8n for a repeated INS.  TODO: Fix this someday.
      */
     var nCycles = 5;
 
@@ -1608,8 +1608,7 @@ X86.opOUTSw = function OUTSw()
 
     /*
      * NOTE: 5 + 4n is the cycle time for the 80286; the 80186/80188 has different values: 14 cycles for
-     * an unrepeated INS, and 8 + 8n for a repeated INS.  However, accurate cycle times for the 80186/80188 is
-     * low priority. TODO: Fix this someday.
+     * an unrepeated INS, and 8 + 8n for a repeated INS.  TODO: Fix this someday.
      */
     var nCycles = 5;
 
@@ -3190,7 +3189,9 @@ X86.opGRP2wn = function GRP2wn()
 X86.opRETn = function RETn()
 {
     var n = this.getIPWord() << (this.dataSize >> 2);
-    this.setIP(this.popWord());
+    var newIP = this.popWord();
+    if (DEBUG) this.printMessage(" returning to " + str.toHex(this.segCS.sel, 4) + ':' + str.toHex(newIP, this.dataSize << 1), this.bitsMessage, true);
+    this.setIP(newIP);
     if (n) this.setSP(this.getSP() + n);            // TODO: optimize
     this.nStepCycles -= this.cycleCounts.nOpCyclesRetn;
 };
@@ -3202,7 +3203,9 @@ X86.opRETn = function RETn()
  */
 X86.opRET = function RET()
 {
-    this.setIP(this.popWord());
+    var newIP = this.popWord();
+    if (DEBUG) this.printMessage(" returning to " + str.toHex(this.segCS.sel, 4) + ':' + str.toHex(newIP, this.dataSize << 1), this.bitsMessage, true);
+    this.setIP(newIP);
     this.nStepCycles -= this.cycleCounts.nOpCyclesRet;
 };
 
@@ -3286,8 +3289,7 @@ X86.opENTER = function ENTER()
     var bLevel = this.getIPByte() & 0x1f;
     /*
      * NOTE: 11 is the minimum cycle time for the 80286; the 80186/80188 has different cycle times: 15, 25 and
-     * 22 + 16 * (bLevel - 1) for bLevel 0, 1 and > 1, respectively.  However, accurate cycle times for the 80186/80188
-     * is low priority. TODO: Fix this someday.
+     * 22 + 16 * (bLevel - 1) for bLevel 0, 1 and > 1, respectively.  TODO: Fix this someday.
      */
     this.nStepCycles -= 11;
     this.pushWord(this.regEBP);
@@ -3316,8 +3318,7 @@ X86.opLEAVE = function LEAVE()
     this.setSP((this.getSP() & ~this.segSS.addrMask) | (this.regEBP & this.segSS.addrMask));
     this.regEBP = (this.regEBP & ~this.dataMask) | (this.popWord() & this.dataMask);
     /*
-     * NOTE: 5 is the cycle time for the 80286; the 80186/80188 has a cycle time of 8.  However, accurate cycle
-     * counts for the 80186/80188 is low priority. TODO: Fix this someday.
+     * NOTE: 5 is the cycle time for the 80286; the 80186/80188 has a cycle time of 8.  TODO: Fix this someday.
      */
     this.nStepCycles -= 5;
 };
@@ -3648,8 +3649,11 @@ X86.opOUTw = function OUTw()
 X86.opCALL = function CALL()
 {
     var disp = this.getIPWord();
-    this.pushWord(this.getIP());
-    this.setIP(this.getIP() + disp);
+    var oldIP = this.getIP();
+    var newIP = oldIP + disp;
+    if (DEBUG) this.printMessage("calling " + str.toHex(newIP, this.dataSize << 1), this.bitsMessage, true);
+    this.pushWord(oldIP);
+    this.setIP(newIP);
     this.nStepCycles -= this.cycleCounts.nOpCyclesCall;
 };
 
diff --git a/modules/pcjs/lib/x86seg.js b/modules/pcjs/lib/x86seg.js
index 33904852d..7af515a63 100644
--- a/modules/pcjs/lib/x86seg.js
+++ b/modules/pcjs/lib/x86seg.js
@@ -243,12 +243,12 @@ X86Seg.prototype.loadIDTProt = function loadIDTProt(nIDT)
 /**
  * checkReadReal(off, cb, fSuppress)
  *
- * TODO: Invoke X86.fnFault.call(this.cpu, X86.EXCEPTION.GP_FAULT) if off is 0xffff and cb is 1;
+ * TODO: Invoke X86.fnFault.call(this.cpu, X86.EXCEPTION.GP_FAULT) if off is 0xffff and cb > 1;
  * also, whether or not the fnFault() call should include an error code, since this is happening in real-mode.
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, or ADDR_INVALID if error (TODO: No error conditions exist yet)
  */
@@ -260,12 +260,12 @@ X86Seg.prototype.checkReadReal = function checkReadReal(off, cb, fSuppress)
 /**
  * checkWriteReal(off, cb, fSuppress)
  *
- * TODO: Invoke X86.fnFault.call(this.cpu, X86.EXCEPTION.GP_FAULT) if off is 0xffff and cb is 1;
+ * TODO: Invoke X86.fnFault.call(this.cpu, X86.EXCEPTION.GP_FAULT) if off is 0xffff and cb > 1;
  * also, whether or not the fnFault() call should include an error code, since this is happening in real-mode.
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, or ADDR_INVALID if error (TODO: No error conditions exist yet)
  */
@@ -279,13 +279,13 @@ X86Seg.prototype.checkWriteReal = function checkWriteReal(off, cb, fSuppress)
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, or ADDR_INVALID if not
  */
 X86Seg.prototype.checkReadProt = function checkReadProt(off, cb, fSuppress)
 {
-    if (off + cb <= this.limit) {
+    if (off + cb - 1 <= this.limit) {
         return (this.base + off)|0;
     }
     return this.checkReadProtDisallowed(off, cb, fSuppress);
@@ -296,13 +296,13 @@ X86Seg.prototype.checkReadProt = function checkReadProt(off, cb, fSuppress)
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, ADDR_INVALID if not
  */
 X86Seg.prototype.checkReadProtDown = function checkReadProtDown(off, cb, fSuppress)
 {
-    if (off + cb > this.limit) {
+    if (off + cb - 1 > this.limit) {
         return (this.base + off)|0;
     }
     return this.checkReadProtDisallowed(off, cb, fSuppress);
@@ -313,7 +313,7 @@ X86Seg.prototype.checkReadProtDown = function checkReadProtDown(off, cb, fSuppre
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, ADDR_INVALID if not
  */
@@ -330,13 +330,13 @@ X86Seg.prototype.checkReadProtDisallowed = function checkReadProtDisallowed(off,
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, ADDR_INVALID if not
  */
 X86Seg.prototype.checkWriteProt = function checkWriteProt(off, cb, fSuppress)
 {
-    if (off + cb <= this.limit) {
+    if (off + cb - 1 <= this.limit) {
         return (this.base + off)|0;
     }
     return this.checkWriteProtDisallowed(off, cb, fSuppress);
@@ -347,13 +347,13 @@ X86Seg.prototype.checkWriteProt = function checkWriteProt(off, cb, fSuppress)
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, ADDR_INVALID if not
  */
 X86Seg.prototype.checkWriteProtDown = function checkWriteProtDown(off, cb, fSuppress)
 {
-    if (off + cb > this.limit) {
+    if (off + cb - 1 > this.limit) {
         return (this.base + off)|0;
     }
     return this.checkWriteProtDisallowed(off, cb, fSuppress);
@@ -364,7 +364,7 @@ X86Seg.prototype.checkWriteProtDown = function checkWriteProtDown(off, cb, fSupp
  *
  * @this {X86Seg}
  * @param {number} off is a segment-relative offset
- * @param {number} cb is number of extra bytes to check (0 or 1)
+ * @param {number} cb is number of bytes to check (1, 2 or 4)
  * @param {boolean} [fSuppress] is true to suppress any errors
  * @return {number} corresponding physical address if valid, ADDR_INVALID if not
  */
diff --git a/modules/shared/lib/embed.js b/modules/shared/lib/embed.js
index b9fe966f1..0f966ae12 100644
--- a/modules/shared/lib/embed.js
+++ b/modules/shared/lib/embed.js
@@ -32,7 +32,7 @@
 
 "use strict";
 
-/* global window: true, XSLTProcessor: false, web: true, Component: true, APPNAME: false, APPVERSION: false, DEBUG: true */
+/* global window: true, XSLTProcessor: false, APPNAME: false, APPVERSION: false, DEBUG: true */
 
 if (typeof module !== 'undefined') {
     var Component;
diff --git a/modules/shared/lib/strlib.js b/modules/shared/lib/strlib.js
index 0a889053b..68d5d7a68 100644
--- a/modules/shared/lib/strlib.js
+++ b/modules/shared/lib/strlib.js
@@ -145,7 +145,7 @@ str.toHex = function(n, cch)
  *
  * Alias for "0x" + str.toHex(b, 2)
  *
- * @param {number|undefined} b is a byte value
+ * @param {number|null|undefined} b is a byte value
  * @return {string} the hex representation of b
  */
 str.toHexByte = function(b)
@@ -158,7 +158,7 @@ str.toHexByte = function(b)
  *
  * Alias for "0x" + str.toHex(w, 4)
  *
- * @param {number|undefined} w is a word (16-bit) value
+ * @param {number|null|undefined} w is a word (16-bit) value
  * @return {string} the hex representation of w
  */
 str.toHexWord = function(w)
@@ -171,7 +171,7 @@ str.toHexWord = function(w)
  *
  * Alias for "0x" + toHex(l)
  *
- * @param {number|undefined} l is a dword (32-bit) value
+ * @param {number|null|undefined} l is a dword (32-bit) value
  * @return {string} the hex representation of w
  */
 str.toHexLong = function(l)
diff --git a/modules/shared/lib/usrlib.js b/modules/shared/lib/usrlib.js
index 63f0d0db6..455d07f7e 100644
--- a/modules/shared/lib/usrlib.js
+++ b/modules/shared/lib/usrlib.js
@@ -39,7 +39,7 @@ var usr = {};
  *
  * @param {Array} a is an array
  * @param {number|string|Array|Object} v
- * @param {function((number|string), (number|string))} [fnCompare]
+ * @param {function((number|string|Array|Object), (number|string|Array|Object))} [fnCompare]
  * @return {number} the index of matching entry if non-negative, otherwise the index of the insertion point
  */
 usr.binarySearch = function(a, v, fnCompare) {
@@ -73,7 +73,7 @@ usr.binarySearch = function(a, v, fnCompare) {
  *
  * @param {Array} a is an array
  * @param {number|string|Array|Object} v is the value to insert
- * @param {function((number|string), (number|string))} [fnCompare]
+ * @param {function((number|string|Array|Object), (number|string|Array|Object))} [fnCompare]
  */
 usr.binaryInsert = function(a, v, fnCompare) {
     var index = usr.binarySearch(a, v, fnCompare);