diff --git a/Makefile b/Makefile
index b073058..596d3e1 100644
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,7 @@ loader : loader.omf loader.rii | hfs24.po
 # bootblock.omf : bootblock.obj
 # 	mpw linkiigs bootblock.obj -o bootblock.omf
 
-bootblock.obj : bootblock.aii hfs.aii
+bootblock.obj : bootblock.aii hfs.aii smartport.aii
 # 	mpw asmiigs bootblock.aii -o bootblock.obj
 
 loader.obj : loader.aii hfs.aii macros.aii
diff --git a/bootblock.aii b/bootblock.aii
index 31b53e8..85bab33 100644
--- a/bootblock.aii
+++ b/bootblock.aii
@@ -9,40 +9,68 @@
 
 	include 'hfs.aii'
 
+
 	string asis
 	blanks on
 
 __smartport__	set 1
 
+	if __smartport__ then
+	include 'smartport.aii'
+	endif
+
+
+;
+; 32-bit version large volumes.
+ExtendedExtent		RECORD 0
+startBlock		ds.l	1	; offset: $0 (0)	;  first allocation block 
+blockCount		ds.l	1	; offset: $4 (8)	;  number of allocation blocks 
+sizeof			EQU *		; size:   $8 (8)
+			ENDR
+
+
+
 zp	record 0
 slot	ds.w	1
 ;vector	ds.w	1
 
-offset		ds.w	1
+startingBlock	ds.w	1
+
+blockMultiplier	ds.w	1
 bnum		ds.w	1
 count		ds.w	1
-extents		ds.b	3*HFSExtentDescriptor.sizeof
+
+extents		ds.b	3*ExtendedExtent.sizeof
+
+
+; multiplication stuff
+m1		ds.w	1
+m2		ds.l	1
+m3		ds.l	1
+
+	if * >= $42 then
+	aerror 'too much zero-page space'
+	endif
 
 	endr
 
 	if not __smartport__ then
 
-pro	record $42
-cmd	ds.b 1
-unit	ds.b 1
-buffer	ds.b 2
-block	ds.b 2
-	endr
+pro		record $42
+cmd		ds.b 1
+unit		ds.b 1
+dataBuffer	ds.b 2
+blockNumber	ds.b 2
+		endr
 
 	endif
 
-data	record $2000
-	ds.b	512
-	endr
+buffer	equ $2000
 
 
-	entry read_block, read_block_abs, read_extent_block
+	entry read_block_abs, read_extent_block
 	entry vector
+	entry extent_to_extent
 
 boot	proc
 	longi off
@@ -56,6 +84,7 @@ boot	proc
 	if not __smartport__ then
 	stx pro.unit
 	endif
+
 	txa
 	lsr a
 	lsr a
@@ -113,14 +142,16 @@ ok
 	longa on
 
 
-	stz offset
+;	stz startingBlock
+;	stz drAlBlkSiz
 	stz bnum
 	stz count
 
 	if not __smartport__ then
-	lda #data
-	sta pro.buffer
+	lda #buffer
+	sta pro.dataBuffer
 	endif
+	ldx #0
 	lda #2
 	jsr read_block_abs
 
@@ -129,6 +160,9 @@ ok
 ;
 ; wait a minute... max 65535 blocks, therefore high word of allocation block, etc, always 0.
 ; i assume hfs use 32-bit links in the btree for in-memory use (24-bit or 32 pointers)
+;
+; actually, offset could be 32-bit due to large allocation blocks. however, that's unreasonably large for the
+; catalog file or boot loader file.
 
 ;
 ; search for a file named ! in the root directory.
@@ -136,33 +170,50 @@ ok
 ;
 ;
 	with HFSMasterDirectoryBlock
-	lda data+drAlBlSt
+	lda buffer+drAlBlSt
 	xba
-	sta offset
+	sta startingBlock
+; drAlBlkSiz is actually a 32-bit number.
+;
+;	lda buffer+drAlBlkSiz+2
+;	xba
+;	sta drAlBlkSiz
+;	xba
+	lda buffer+drAlBlkSiz+1
+	xba
+	lsr a ; / 2
+	sta blockMultiplier ; 0 = 512 byte blocks, 1 = 
+
+
+;	ldx #3*HFSExtentDescriptor.sizeof-2
+;@cloop	lda buffer+drCTExtRec,x
+;	xba
+;	sta extents,x
+;	dex
+;	dex
+;	bpl @cloop
+
+	ldy #drCTExtRec ; offset
+	jsr extent_to_extent
+
 
-	ldx #3*HFSExtentDescriptor.sizeof-2
-@cloop	lda data+drCTExtRec,x
-	xba
-	sta extents,x
-	dex
-	dex
-	bpl @cloop
 	endwith
 
-;	lda offset
+;	lda drAlBlSt
 ;	clc
 ;	adc extents
-	lda extents
-	jsr read_block
+	lda #0
+	ldx #0
+	jsr read_extent_block
 
 	;
 	; block should be a btree header block. find the first leaf node.
 	;
 	with BTHeaderRec
-;	lda data+BTNodeDescriptor.sizeof+firstLeafNode
+;	lda buffer+BTNodeDescriptor.sizeof+firstLeafNode
 ;	xba
 ;	sta leaf+2
-	lda data+BTNodeDescriptor.sizeof+firstLeafNode+2
+	lda buffer+BTNodeDescriptor.sizeof+firstLeafNode+2
 	xba
 ;	sta bnum
 
@@ -170,11 +221,9 @@ ok
 	;
 	; assert leaf < # allocated lbocks?
 	;
-	;lda leaf
-	; s/b leaf + cat extent + offset; todo - this offset is in terms of the catalog extent
 	jsr read_extent_block
 
-	lda data+BTNodeDescriptor.numRecords ; # of records
+	lda buffer+BTNodeDescriptor.numRecords ; # of records
 	beq advance
 
 	xba
@@ -183,19 +232,19 @@ ok
 again
 	ldx #512-2 ; last entry 
 @loop
-	lda data,x ; entry offset
+	lda buffer,x ; entry offset
 	xba
 	tay
-	lda data+HFSCatalogKey.parentID,y ; parent id
+	lda buffer+HFSCatalogKey.parentID,y ; parent id
 	bne notfound
-	lda data+HFSCatalogKey.parentID+2,y
+	lda buffer+HFSCatalogKey.parentID+2,y
 	xba
 	cmp #2
 	blt @next
 	beq @name
 	bge notfound
 @name	; name is a p-string.
-	lda data+HFSCatalogKey.nodeName,y
+	lda buffer+HFSCatalogKey.nodeName,y
 	cmp #$2101 ; pstr !
 	beq found
 	bge notfound
@@ -205,7 +254,7 @@ again
 	dec count
 	bne @loop
 advance ; next block!
-	lda data+BTNodeDescriptor.fLink+2
+	lda buffer+BTNodeDescriptor.fLink+2
 	beq notfound
 	xba
 	jsr read_extent_block
@@ -224,12 +273,12 @@ found
 
 	; assume < 65535 bytes :)
 	with HFSCatalogFile
-	lda data+8+recordType,y
+	lda buffer+8+recordType,y
 	and #$00ff
 	cmp #kHFSFileRecord
 	bne notfound
 
-	lda data+8+dataPhysicalSize+2,y
+	lda buffer+8+dataPhysicalSize+2,y
 ;	xba
 	lsr a ; >>9 since already xba
 	and #%01111111
@@ -237,35 +286,43 @@ found
 	sta count
 
 	; todo -- all extents...
-	lda data+8+dataExtents,y
-	xba
-	sta extents
-	lda data+8+dataExtents+2,y
-	xba
-	sta extents+2
+;	lda buffer+8+dataExtents,y
+;	xba
+;	sta extents
+;	lda buffer+8+dataExtents+2,y
+;	xba
+;	sta extents+2
+
+	tya
+	clc
+	adc #8+dataExtents
+	tay
+	jsr extent_to_extent
+
 
 	; now load the blocks and
 ;	lda #$2000
 ;	if __smartport__ then
-;	sta sp.buffer
+;	sta sp.dataBuffer
 ;	else
-;	sta pro.buffer
+;	sta pro.dataBuffer
 ;	endif
 
 	stz bnum
 @loop
 	lda bnum
+	ldx #0
 	jsr read_extent_block
 	inc bnum
 	lda #512
 	clc
 	if __smartport__ then
-	import sp_buffer
-	adc sp_buffer
-	sta sp_buffer
+	import sp:IOBlockDCB
+	adc sp.dataBuffer
+	sta sp.dataBuffer
 	else
-	adc pro.buffer
-	sta pro.buffer
+	adc pro.dataBuffer
+	sta pro.dataBuffer
 	endif
 	dec count
 	bne @loop
@@ -284,23 +341,18 @@ found
 
 	if __smartport__ then
 sp	record 
-	entry sp_buffer, sp_block
-
-ReadBlock	equ $01
-pcount	dc.b	3
-unit	dc.b	1 ; hard-coded
-sp_buffer
-buffer	dc.w	$2000
-sp_block
-block	dc.l	1 ; actually 24-bit
 
+pCount		dc.b	3
+unit		dc.b	1 ; hard-coded
+dataBuffer	dc.w	$2000
+blockNumber	dc.l	1 ; actually 24-bit
 
 	endr
 	endif
 
 
-read_block proc
-	entry read_block_abs
+read_block_abs proc
+	entry read_block_abs_long
 	entry vector
 
 	; input
@@ -308,27 +360,26 @@ read_block proc
 	; will be adjusted for allocation block offset
 	;
 	with zp
-	clc
-	adc offset
+;	clc
+;	adc startingBlock
 
-read_block_abs
-;
-; based on testing, this drops into emulation mode, so do it and recover.
-;
+;read_block_abs
 
 	if __smartport__ then
-	sta sp.block
+	sta sp.blockNumber
+	stx sp.blockNumber+2
 	else
-	sta pro.block
+	sta pro.blockNumber
 	endif
 
+read_block_abs_long
 	php
 	sec
 	xce
 	dc.b $20 ; jsr
 vector	dc.w $ffff
 	if __smartport__ then
-	dc.b sp.ReadBlock
+	dc.b Command.ReadBlock
 	dc.w sp
 	endif
 
@@ -339,36 +390,178 @@ vector	dc.w $ffff
 @fail	brk $ea
 	endp
 
+
+	macro
+	ifcs &p1,&p2
+	bcc @0
+	&p1 &p2
+@0
+	mend
+
 read_extent_block proc
 ; a = block #
 
 ; This doesn't check beyond the 3rd extent
 
-	with zp,HFSExtentDescriptor
+	import read_block_abs_long
+
+	with zp,ExtendedExtent
 
 @0
-	cmp extents+0+blockCount
+	cmp extents+(sizeof*0)+blockCount
 	bcs @1
 ;	clc
-	adc extents+0+startBlock
-	bra read_block
+	ldx #sizeof*0+startBlock
+	bra found
 
-@1	sbc extents+0+blockCount
-	cmp extents+4+blockCount
+@1	sbc extents+(sizeof*0)+blockCount
+	cmp extents+(sizeof*1)+blockCount
 	bcs @2
 ;	clc
-	adc extents+4+startBlock
-	bra read_block
+	ldx #sizeof*1+startBlock
+	bra found
 
-@2	sbc extents+4+blockCount
-	cmp extents+8+blockCount
+@2	sbc extents+(sizeof*1)+blockCount
+	cmp extents+(sizeof*2)+blockCount
 	bcs @3
-	adc extents+8+startBlock
-	bra read_block
+	ldx #sizeof*2+startBlock
+	bra found
 
 @3	brk $ea
+
+found	;
+	clc
+	adc extents,x
+	sta sp.blockNumber
+	lda #0
+	adc extents+2,x
+	sta sp.blockNumber+2
+
+	clc
+	lda startingBlock
+	adc sp.blockNumber
+	sta sp.blockNumber
+	lda #0
+	adc sp.blockNumber+2
+	sta sp.blockNumber+2
+	bra read_block_abs_long
+	endp
+
+
+multiply proc
+; inputs: m1 (16-bit), m2 (32-bit)
+; outputs: m3 (32-bit)
+; m1, m2 clobbered
+	with zp
+
+	stz m3
+	stz m3+2
+	lda m1
+	beq rts
+	lda m2
+	ora m3
+	beq rts
+
+loop
+	lsr m1
+	bcc next
+
+add	clc
+	lda m2
+	adc m3
+	sta m3
+	lda m2+2
+	adc m3+2
+	sta m3+2
+
+next	asl m2
+	rol m2+2
+	lda m1
+	bne loop	
+
+rts	rts
+	endp
+
+extent_to_extent proc
+	; y = offset into buffer.
+	; clobbers x, y
+	with zp,ExtendedExtent
+
+	import multiply
+
+	ldx #0
+loop1
+	lda buffer,y
+	xba
+	sta extents,x
+	stz extents+2,x
+	iny
+	iny
+	inx
+	inx
+	inx
+	inx
+	cpx #sizeof*3
+	blt loop1
+
+; now multiply...
+	lda blockMultiplier
+	dec a
+	beq offset
+
+	ldx #sizeof*3-4
+loop2
+	lda blockMultiplier
+	sta m1
+	lda extents+0,x
+	sta m2
+	stz m2+2
+	jsr multiply
+	lda m3
+	sta extents+0,x
+	lda m3+2
+	sta extents+2,x
+
+	dex
+	dex
+	dex
+	dex
+	bpl loop2
+
+
+offset
+	if 0 then
+; now add the block offset to the starting block.
+	lda startingBlock
+	clc
+	adc extents+(ExtendedExtent.sizeof*0)+startBlock
+	sta extents+(ExtendedExtent.sizeof*0)+startBlock
+	lda #0
+	adc extents+(ExtendedExtent.sizeof*0)+startBlock+2
+	sta extents+(ExtendedExtent.sizeof*0)+startBlock+2
+
+	lda startingBlock
+	clc
+	adc extents+(ExtendedExtent.sizeof*1)+startBlock
+	sta extents+(ExtendedExtent.sizeof*1)+startBlock
+	lda #0
+	adc extents+(ExtendedExtent.sizeof*1)+startBlock+2
+	sta extents+(ExtendedExtent.sizeof*1)+startBlock+2
+
+	lda startingBlock
+	clc
+	adc extents+(ExtendedExtent.sizeof*2)+startBlock
+	sta extents+(ExtendedExtent.sizeof*2)+startBlock
+	lda #0
+	adc extents+(ExtendedExtent.sizeof*2)+startBlock+2
+	sta extents+(ExtendedExtent.sizeof*2)+startBlock+2
+
+	endif
+	rts
 	endp
 
 
 
+
+
 	end
diff --git a/loader.aii b/loader.aii
index b400af9..3256b58 100644
--- a/loader.aii
+++ b/loader.aii
@@ -18,9 +18,24 @@
 
 __smartport__	set 1
 
+
+	if __smartport__ then
+	include 'smartport.aii'
+	endif
+
+;
+; 32-bit version large volumes.
+ExtendedExtent		RECORD 0
+startBlock		ds.l	1	; offset: $0 (0)	;  first allocation block 
+blockCount		ds.l	1	; offset: $4 (8)	;  number of allocation blocks 
+sizeof			EQU *		; size:   $8 (8)
+			ENDR
+
+
+
 buffer	equ $3000
 
-dp	record 0
+zp	record 0
 ptr	ds.l 1
 path	ds.l 1
 
@@ -38,25 +53,42 @@ at	ds.w 1
 st	ds.w 1
 file_id	ds.l 1
 
+
+
+extents		ds.b	3*ExtendedExtent.sizeof
+
+; multiplication stuff
+m1		ds.w	1
+m2		ds.l	1
+m3		ds.l	1
+
+
+
+; too much zp space...
+	if not __smartport__ and * >= $42 then
+	aerror 'too much zero-page space'
+	endif
+
 	endr
 
 
 
 
 	if not __smartport__ then
-pro	record $42
-cmd	ds.b 1
-unit	ds.b 1
-buffer	ds.b 2
-block	ds.b 2
-	endr
+pro		record $42
+cmd		ds.b 1
+unit		ds.b 1
+dataBuffer	ds.b 2
+blockNumber	ds.b 2
+		endr
 
 	endif
 
 
-	entry read_block, read_block_abs
+	entry read_block_abs, read_block_abs_long
 	entry prepare_path, cat_lookup
 	entry read_cat_block, read_file_block
+	entry extent_to_extent
 
 
 header	proc
@@ -82,10 +114,12 @@ data	record
 ;unit		dc.w 0
 ;vector		dc.w 0
 
-block_offset	dc.w 0
+startingBlock	dc.w 0
+blockMultiplier	dc.w 0
 
-cat_extents	dcb.w 6, 0
-file_extents	dcb.w 6, 0
+
+cat_extents	ds.b 3*ExtendedExtent.sizeof
+file_extents	ds.b 3*ExtendedExtent.sizeof
 
 cat_root	dc.w 0
 
@@ -106,21 +140,22 @@ cat_str		dcb.b 32, 0
 	endr
 
 	if __smartport__ then
-sp	record
-ReadBlock	equ $01
-pcount	dc.b	3
-unit	dc.b	1
-buffer	dc.w	$3000 ; name conflict...
-block	dc.l	0 ; actually 24-bit
-	endr
+sp		record
+pCount		dc.b	3
+unit		dc.b	1
+dataBuffer	dc.w	$3000 ; name conflict...
+blockNumber	dc.l	0 ; actually 24-bit
+		endr
 	endif
 
 
+_stack	ds.w 1
+
 getbootname proc
 	; getbootname(GSString *)
 	; return string needs a leading colon.
 
-	with dp
+	with zp
 
 	plx ; rts
 	ply
@@ -133,13 +168,26 @@ getbootname proc
 	phk
 	plb
 
+	; prepare the stack for emulation mode
+	tsx
+	stx _stack
+	ldx #$01ff ; should be enough space
+	txs
+
+
 ; get the volume name from the HFS MDB....
 	if not __smartport__ then
 	lda #buffer
-	sta pro.buffer
+	sta pro.dataBuffer
 	endif
 	lda #2
+	ldx #0
 	jsr read_block_abs
+
+	; restore the stack. does not affect a/carry
+	ldx _stack
+	txs
+
 	bcs exit	
 
 	with HFSMasterDirectoryBlock
@@ -176,7 +224,7 @@ exit
 getfstname proc
 	; getfstname(GSString *)
 
-	with dp
+	with zp
 
 	plx ; rts
 	ply
@@ -211,7 +259,7 @@ name	str.w 'hfs.fst'
 
 readfile proc
 ; (eof, aux type, file type) readfile(GSString *, void *)
-	with dp
+	with zp
 
 	plx ; rts
 	ply
@@ -228,6 +276,12 @@ readfile proc
 	phk
 	plb
 
+	; prepare the stack for emulation mode
+	tsx
+	stx _stack
+	ldx #$01ff ; should be enough space
+	txs
+
 
 	jsr prepare_path
 	bcs exit
@@ -235,6 +289,9 @@ readfile proc
 	jsr cat_lookup
 	bcs exit
 
+
+
+
 	; now read file, one block at a time,
 	; and copy to ptr.
 	lda blocks
@@ -243,7 +300,7 @@ readfile proc
 
 	if not __smartport__ then
 	lda #buffer
-	sta pro.buffer
+	sta pro.dataBuffer
 	endif
 	; need to re-set cmd/slot as well?
 
@@ -280,6 +337,9 @@ rdone
 
 ; ...
 
+	ldx _stack
+	txs
+
 	; stack: b, rts,
 	lda ft
 	sta 4,s
@@ -292,7 +352,12 @@ rdone
 
 	lda #0
 	clc
+	plb
+	rts
+
 exit
+	ldx _stack
+	txs
 	plb
 	rts
 
@@ -300,7 +365,7 @@ exit
 
 prepare_path proc
 	
-	with dp, data
+	with zp, data
 
 ; optimism
 	stz r0 ; offset into path
@@ -445,135 +510,153 @@ s3	dc.b 'xxSYSTEM:FSTS:'
 	endp
 
 
-read_block proc
-	entry read_block_abs
-	entry vector
-
-	; input
-	; a = hfs block #
-	; will be adjusted for allocation block offset
-	;
-	with dp
-	clc
-	adc data.block_offset
-
-read_block_abs
-
-
-	; todo -- need to save/restore dp and stack
-
-	if __smartport__ then
-	sta sp.block
-	else
-	sta pro.block
-	endif
-
-;
-; need to save/restore the stack.  start.gs.os will call w/ high stack
-;
-	tsc
-	sta _stack
-	lda #$01bf ; should be enough space
-	tcs
-
-	clc
-	php
-	sec
-	xce
-	dc.b $20 ; jsr
-vector	dc.w $ffff
-	if __smartport__ then
-	dc.b sp.ReadBlock
-	dc.w sp
-	endif
-
-	bcs @fail
-	xce
-	plp
-	lda _stack
-	tcs
-	lda #0
-	rts
-
-@fail	
-	clc
-	xce
-	plp
-	tax ; save
-	lda _stack
-	tcs	
-	sec
-	txa
-	and #$ff
-	rts
-
-_stack	ds.w 1
-
-	endp
-
-
 read_file_block proc
 ; a = block #
 
-	with data,HFSExtentDescriptor
+	with data,ExtendedExtent
 
 @0
-	cmp file_extents+0+blockCount
+	cmp file_extents+(sizeof*0)+blockCount
 	bcs @1
 ;	clc
-	adc file_extents+0+startBlock
-	bra read_block
+	ldx #sizeof*0+startBlock
+	bra found
 
-@1	sbc file_extents+0+blockCount
-	cmp file_extents+4+blockCount
+@1	sbc file_extents+(sizeof*0)+blockCount
+	cmp file_extents+(sizeof*1)+blockCount
 	bcs @2
 ;	clc
-	adc file_extents+4+startBlock
-	bra read_block
+	ldx #sizeof*1+startBlock
+	bra found
 
-@2	sbc file_extents+4+blockCount
-	cmp file_extents+8+blockCount
+@2	sbc file_extents+(sizeof*1)+blockCount
+	cmp file_extents+(sizeof*2)+blockCount
 	bcs @3
-	adc file_extents+8+startBlock
-	bra read_block
+	ldx #sizeof*2+startBlock
+	bra found
 
 @3
 	lda #outOfRange ; too big
 	sec
 	rts
 
+
+found	;
+	clc
+	adc file_extents,x
+	sta sp.blockNumber
+	lda #0
+	adc file_extents+2,x
+	sta sp.blockNumber+2
+
+	clc
+	lda startingBlock
+	adc sp.blockNumber
+	sta sp.blockNumber
+	lda #0
+	adc sp.blockNumber+2
+	sta sp.blockNumber+2
+	bra read_block_abs_long
+
 	endp
 
 read_cat_block proc
 ; a = block #
 
-	with data,HFSExtentDescriptor
+
+	with data,ExtendedExtent
 
 @0
-	cmp cat_extents+0+blockCount
+	cmp cat_extents+(sizeof*0)+blockCount
 	bcs @1
 ;	clc
-	adc cat_extents+0+startBlock
-	bra read_block
+	ldx #sizeof*0+startBlock
+	bra found
 
-@1	sbc cat_extents+0+blockCount
-	cmp cat_extents+4+blockCount
+@1	sbc cat_extents+(sizeof*0)+blockCount
+	cmp cat_extents+(sizeof*1)+blockCount
 	bcs @2
 ;	clc
-	adc cat_extents+4+startBlock
-	bra read_block
+	ldx #sizeof*1+startBlock
+	bra found
 
-@2	sbc cat_extents+4+blockCount
-	cmp cat_extents+8+blockCount
+@2	sbc cat_extents+(sizeof*1)+blockCount
+	cmp cat_extents+(sizeof*2)+blockCount
 	bcs @3
-	adc cat_extents+8+startBlock
-	bra read_block
+	ldx #sizeof*2+startBlock
+	bra found
 
 @3
 	lda #outOfRange ; too big
 	sec
 	rts
 
+found	;
+	clc
+	adc cat_extents,x
+	sta sp.blockNumber
+	lda #0
+	adc cat_extents+2,x
+	sta sp.blockNumber+2
+
+	clc
+	lda startingBlock
+	adc sp.blockNumber
+	sta sp.blockNumber
+	lda #0
+	adc sp.blockNumber+2
+	sta sp.blockNumber+2
+	bra read_block_abs_long
+
+	endp
+
+
+
+
+read_block_abs proc
+	entry read_block_abs_long
+	entry vector
+
+	; input
+	; a = hfs block #
+	; will be adjusted for allocation block offset
+	;
+;	clc
+;	adc data.startingBlock
+
+	if __smartport__ then
+	sta sp.blockNumber
+	stx sp.blockNumber+2
+	else
+	sta pro.blockNumber
+	endif
+
+read_block_abs_long
+	php
+	sec
+	xce
+	dc.b $20 ; jsr
+vector	dc.w $ffff
+	if __smartport__ then
+	dc.b Command.ReadBlock
+	dc.w sp
+	endif
+
+	bcs @fail
+	xce
+	plp
+	lda #0
+	clc
+	rts
+
+@fail	
+	clc
+	xce
+	plp
+	and #$ff
+	sec
+	rts
+
 	endp
 
 
@@ -585,9 +668,9 @@ cat_lookup proc
 
 	with data
 
-bnum	equ dp.r0
-prev	equ dp.r1
-count	equ dp.r2
+bnum	equ zp.r0
+prev	equ zp.r1
+count	equ zp.r2
 
 	; search for a file and a parent directory.
 
@@ -795,7 +878,7 @@ match	proc
 ; a match!
 ; store the file type, aux type, eof, and extent pointers.
 
-	with dp, data
+	with zp, data
 
 	lda buffer+HFSCatalogKey.keyLength,y
 ;	and #$ff
@@ -830,7 +913,7 @@ folder
 	sta ft
 	lda #$0d
 	sta st ; storage type
-	ldx #12-2
+	ldx #3*ExtendedExtent.sizeof-2
 @eloop
 	stz file_extents,x
 	dex
@@ -871,30 +954,19 @@ file
 	lda #1
 	sta st ; storage type
 
-
-	lda buffer+dataExtents+0,y
-	xba
-	sta file_extents+0
-
-	lda buffer+dataExtents+2,y
-	xba
-	sta file_extents+2
-
-	lda buffer+dataExtents+4,y
-	xba
-	sta file_extents+4
-
-	lda buffer+dataExtents+6,y
-	xba
-	sta file_extents+6
-
-	lda buffer+dataExtents+8,y
-	xba
-	sta file_extents+8
-
-	lda buffer+dataExtents+10,y
-	xba
-	sta file_extents+10
+	phy ; save
+	tya
+	clc
+	adc #dataExtents
+	tay
+;	ldy #dataExtents
+	jsr extent_to_extent
+	lda #3*ExtendedExtent.sizeof-1
+	ldx #extents
+	ldy #file_extents
+	mvn $00,$00
+	; a, x, y clobbered.
+	ply
 
 	lda buffer+fileID+2,y
 	xba
@@ -906,7 +978,7 @@ file
 ; file type aux type logic.
 ; only support pdos encoding, nothing fancy.
 ; 'p' filetype aux type pdos
-; where filetype = 80bit, aux type = 16 bit big endian
+; where filetype = 8 bit, aux type = 16 bit big endian
 
 	stz ft
 	stz at
@@ -964,7 +1036,7 @@ startup proc
 ; read :system:start.gsos, load into memory @ $6800
 ; aux type is stored in auxtype
 
-	with dp, data
+	with zp, data
 
 ; assume 16-bit, etc.   
 
@@ -982,7 +1054,7 @@ startup proc
 
 	if not __smartport__ then
 	lda #buffer
-	sta pro.buffer
+	sta pro.dataBuffer
 	short m
 	lda #1
 	sta pro.cmd
@@ -991,27 +1063,35 @@ startup proc
 
 	with HFSMasterDirectoryBlock
 	lda #2
+	ldx #0
 	jsr read_block_abs
-	; can't really fail...
+	; shouldn't fail.
 	lda buffer+drAlBlSt
 	xba
-	sta block_offset
+	sta startingBlock
 
-	ldx #3*HFSExtentDescriptor.sizeof-2
-@cloop	lda buffer+drCTExtRec,x
+	lda buffer+drAlBlkSiz+1
 	xba
-	sta cat_extents,x
-	dex
-	dex
-	bpl @cloop
+	lsr a ; / 2
+	sta blockMultiplier
+
+; catalog extents
+	ldy #drCTExtRec ; offset
+	jsr extent_to_extent
+
+	lda #3*ExtendedExtent.sizeof-1
+	ldx #extents
+	ldy #cat_extents
+	mvn $00,$00
+	; a, x, y clobbered. 
 
 ; save the volume name while we're at it?
 
 	endwith
 
 ; find the root node.
-	lda cat_extents
-	jsr read_block
+	lda #0
+	jsr read_cat_block
 
 	with BTHeaderRec
 	lda buffer+BTNodeDescriptor.sizeof+rootNode+2
@@ -1113,9 +1193,9 @@ read
 
 	lda #$6800
 	if __smartport__ then
-	sta sp.buffer
+	sta sp.dataBuffer
 	else
-	sta pro.buffer
+	sta pro.dataBuffer
 	endif
 
 @loop	lda r0
@@ -1124,11 +1204,11 @@ read
 ;	clc
 	lda #512
 	if __smartport__ then
-	adc sp.buffer
-	sta sp.buffer
+	adc sp.dataBuffer
+	sta sp.dataBuffer
 	else
-	adc pro.buffer
-	sta pro.buffer
+	adc pro.dataBuffer
+	sta pro.dataBuffer
 	endif
 	inc r0
 	dec blocks
@@ -1140,9 +1220,9 @@ read
 
 	lda #buffer
 	if __smartport__ then
-	sta sp.buffer
+	sta sp.dataBuffer
 	else
-	sta pro.buffer ; kind of important...
+	sta pro.dataBuffer ; kind of important...
 	endif
 
 	lda #0
@@ -1167,4 +1247,89 @@ gsos	str.w 'START.GS.OS'
 	dcb.b 1,0
 	endp
 
+
+multiply proc
+; inputs: m1 (16-bit), m2 (32-bit)
+; outputs: m3 (32-bit)
+; m1, m2 clobbered
+	with zp
+
+	stz m3
+	stz m3+2
+	lda m1
+	beq rts
+	lda m2
+	ora m3
+	beq rts
+
+loop
+	lsr m1
+	bcc next
+
+add	clc
+	lda m2
+	adc m3
+	sta m3
+	lda m2+2
+	adc m3+2
+	sta m3+2
+
+next	asl m2
+	rol m2+2
+	lda m1
+	bne loop	
+
+rts	rts
+	endp
+
+extent_to_extent proc
+	; y = offset into buffer.
+	; clobbers x, y
+	with zp, data
+	import multiply
+
+	ldx #0
+loop1
+	lda buffer,y
+	xba
+	sta extents,x
+	stz extents+2,x
+	iny
+	iny
+	inx
+	inx
+	inx
+	inx
+	cpx #3*4*2
+	blt loop1
+
+; now multiply...
+	lda blockMultiplier
+	dec a
+	beq rts
+
+	ldx #3*4*2-4
+loop2
+	lda blockMultiplier
+	sta m1
+	lda extents+0,x
+	sta m2
+	stz m2+2
+	jsr multiply
+	lda m3
+	sta extents+0,x
+	lda m3+2
+	sta extents+2,x
+
+	dex
+	dex
+	dex
+	dex
+	bpl loop2
+
+
+rts	rts
+	endp
+
+
 	end
diff --git a/smartport.aii b/smartport.aii
new file mode 100644
index 0000000..a7462be
--- /dev/null
+++ b/smartport.aii
@@ -0,0 +1,87 @@
+
+
+Command 	record 0
+Status		equ $00
+ReadBlock	equ $01
+WriteBlock	equ $02
+Format		equ $03
+Control		equ $04
+Init		equ $05
+Open		equ $06 ; character device
+Close		equ $07 ; character device
+Read		equ $08
+Write		equ $09
+SetFormatOption	equ $0a
+GetFormatOption	equ $0b
+		endr
+
+Error		record 0
+badCommand	equ $01
+badPcount	equ $04
+busError	equ $06
+badUnit		equ $11
+noInterrupt	equ $1f
+badCode		equ $21
+badParameter	equ $22
+ioError		equ $27
+noDrive		equ $28
+noWrite		equ $2b
+badBlock	equ $2d
+diskSwitch	equ $2e
+offLine		equ $2f
+; $30-$3f = device specific
+; $40-$4f = reserved
+; $50-$5f = non fatal
+; $60-$6f = non fatal version of $20-$2f
+ioTerm		equ $69	
+		endr
+
+StatusDCB	record 0
+pCount		ds.b 1
+unit		ds.b 1
+statusList	ds.w 1
+statusCode	ds.b 1
+		endr
+
+IOBlockDCB	record 0
+pCount		ds.b 1
+unit		ds.b 1
+dataBuffer	ds.w 1
+blockNumber	ds.b 3 ; 24-bit
+		endr
+
+FormatDCB	record 0
+pCount		ds.b 1
+unit		ds.b 1
+		endr
+
+ControlDCB	record 0
+pCount		ds.b 1
+unit		ds.b 1
+controlList	ds.w 1
+controlCode	ds.b 1
+		endr
+
+InitDCB		record 0
+pCount		ds.b 1
+unit		ds.b 1
+		endr
+
+OpenDCB		record 0
+pCount		ds.b 1
+unit		ds.b 1
+		endr
+
+CloseDCB	record 0
+pCount		ds.b 1
+unit		ds.b 1
+		endr
+
+IODCB		record 0
+pCount		ds.b 1
+unit		ds.b 1
+dataBuffer	ds.w 1
+byteCount	ds.w 1
+address		ds.b 3 ; 24-bit
+		endr
+