title	djdma/format.asm	01-29-82

	.z80

channl	equ	50h		;Start channel address
index	equ	10h		;Delta index status bit
wproct	equ	40h		;Write protected status bit
dready	equ	80h		;Drive ready status bit
home	equ	0a0h		;Internal home-disk routine address
seek	equ	0a3h		;	  seek-track
sdrive	equ	0a6h		;	  set-drive
hsync	equ	0a9h		;	  header-sync
diskd	equ	4001h		;Disk data port
status	equ	4003h		;Status port
contrl	equ	4007h		;Control port

crlfs	equ	0d0ah		;Carraige return / line feed sequence
acr	equ	0dh		;A carraige return character
alf	equ	0ah		;A line feed character
aesc	equ	1bh		;An escape character
adel	equ	7fh		;A delete character
retries	equ	3		;Disk retries before giving up on verify

bdos	equ	5		;Bdos entry address
wcon	equ	2		;Write console function
direct	equ	6		;Direct console I/O
the crc generator
	ld	(de),a		;Change mode
	ld	a,(dsect)	;Get the sector number
	inc	a
	cp	1bh		;Test for last sector +1
dlast	equ	$-1
	ld	(hl),4eh	;First byte of postamble
	jr	nz,$+4		;Zero => all sectors written
	ld	a,1
	ld	(dsect),a	;Update the sector number
	ld	b,35h		;Postamble length less one
ddlbla:	ld	(hl),4eh
	djnz	ddlbla		;Write the postamble
	jr	nz,dmloop
	ld	(hl),4eh	;First fill byte
	ld	b,0		;Double sided bit test
ddsbit	equ	$-1
	ld	a,(dside)
	xor	b		;Conditionally switch the side byte
	ld	(dside),a	;Update the side byte
	ld	(hl),4eh	;Second fill byte
	ld	b,4fh		;Preamble length less one
	ex	Af,Af'		;Save the double sided status
dlblb:	ld	(hl),4eh	;Write a fill byte
	ld	a,(status)
	and	index		;Wait for the index pulse
	jr	z,dlblb
	ex	Af,Af'		;Recover the double sided status
	jr	z,ddlblc	;Zero => track write is done
	ld	a,(iy+2)	;Drive pattern
	or	0ch		;Turn off the step command
	and	0fdh		;Change read/write heads
	ld	(4005h),a	;Update the command register
	ld	(hl),4eh	;First preamble byte
	jp	ddlbl3		;Format the other side
ddlblc:	ld	(hl),4eh	;Trailing fill byte
	ld	(hl),4eh	;Trailing fill byte
	ld	(hl),4eh	;Trailing fill byte
	xor	a
	ld	(de),a		;Turn off the write gate
	ld	a,6
	ld	(4006h),a	;Turn off the controller
	ld	a,40h		;Status code
	ret
ddadvt:	ld	a,(dtrck)	;Get the current track value
	inc	a		;Increment
	ld	(dtrck),a	;Restore the new value
	ret			;Return with current track value
	.dephase
	page
;
;	IBM 8 inch double density formatter routine
;
single	equ	$
	.phase	1030h
sdfmt:	ld	a,0		;Second byte filled with proper drive number
	call	sdrive		;Select the new drive
	ret	nz		;Return if wrong value
	ld	a,(iy+2)	;Get the drive pattern
	or	0fh		;Side 0 and no step command
	ld	(4005h),a	;Update drive control register
	ld	hl,0		;Delay for the head load
sdwait:	dec	hl
	ld	a,h
	or	l
	jr	nz,sdwait
	ld	(ix+0bh),a	;Reset the index counter
sdtrk0:	call	home		;Calibrate the head(s)
	bit	5,(hl)		;Test for track zero
	jr	z,snrext
sdrdy:	ld	hl,status
	bit	7,(hl)		;Test for the drive ready
snrext:	ld	a,82h		;Drive not ready code
	ret	z		;Error exit
	bit	6,(hl)		;Write protect bit
	ld	a,90h		;Write protect error code
	ret	nz
	ld	(ix+0bh),0	;Reset the index counter
	ld	a,(strck)	;Get the new track
	cp	(iy+1)		;Compare with current track
	call	nz,seek		;Do track seek if necessary
	ld	hl,diskd	;Controller data register
	ld	de,contrl	;Control register
	ld	b,28h		;Preamble length
sdlbl1:	ld	a,(status)
	and	index	
	jr	nz,sdlbl1	;Wait for no index pulse
sdlbl2:	ld	a,(status)
	and	index
	jr	z,sdlbl2	;Wait for leading edge of new index pulse
	ld	a,90h		;Clear the crc register & turn on write gate
	ld	(de),a		;Change modes
	ld	a,44h		;Single density & start bit
	ld	(4006h),a	;Start the controller
sdlbl3:	ld	(hl),0ffh
	djnz	sdlbl3		;Write the preamble
	ld	a,80h		;16 bit write mode
	ld	(de),a		;Change modes
	ld	b,0ch		;Zero preamble length
sdlbl4:	ld	(hl),0aah	;Half a zero cell
	djnz	sdlbl4		;Write the zero preamble
	ld	(hl),0f7h	;First half of fc
	ld	a,90h		;8 bit write mode
	ld	(de),a		;Change modes
	ld	(hl),7ah	;Second half of fc
	ld	b,1ah		;Postamble length
sdlbl5:	ld	(hl),0ffh
	djnz	sdlbl5		;Write the postamble

smloop:	ld	a,80h		;16 bit write mode
	ld	(de),a		;Change modes
	ld	b,0ch		;Sector header preamble length
sdlbl6:	ld	(hl),0aah	;Half a zero cell
	djnz	sdlbl6		;Write the preamble
	ld	a,81h		;Enable crc & 16 bit write
	ld	(de),a		;Change modes
	ld	(hl),0f5h	;First half of fe
	ld	a,91h		;Enable crc & 8 bit write
	ld	(de),a		;Change modes
	ld	(hl),7eh	;Second half of fe
	ld	(hl),0		;Write the track
strck	equ	$-1
	lD	(hl),0		;Write the side byte
sside	equ	$-1
	ld	(hl),1		;Write the sector number
ssect	equ	$-1
	ld	(hl),0		;Write the sector length code
	ld	a,0a1h
	ld	(de),a		;Change modes
	ld	(hl),a
	ld	(hl),a		;Write the crc bytes
	ld	a,90h		;Reset the crc
	ld	(de),a		;Change modes
	ld	b,0bh		;Sector header postamble length
sdlbl7:	ld	(hl),0ffh
	djnz	sdlbl7		;Write the postamble
	ld	a,80h		;16 bit write mode
	ld	(de),a		;Change modes
	ld	b,0ch		;Data field preamble length
sdlbl8:	ld	(hl),0aah	;Half a zero cell
	djnz	sdlbl8		;Write the preamble
	ld	a,81h		;Enable crc & 16 bit write
	ld	(de),a		;Change modes
	ld	(hl),0f5h	;First half of fb
	ld	a,91h		;8 bit write
	ld	(de),a		;Change modes
	ld	(hl),6fh	;Second half of fb
	ld	b,80h		;Sector data field length
sdlbl9:	ld	(hl),0e5h
	djnz	sdlbl9		;Write the data field
	ld	a,0a1h
	ld	(de),a		;Change modes
	ld	(hl),a
	ld	(hl),a		;Write the crc bytes
	ld	a,90h		;Reset the crc
	ld	(de),a		;Change modes
	ld	a,(ssect)	;Get the current sector
	inc	a		;Advance
	cp	1bh		;Compare with 27
	ld	(hl),0ffh	;First postamble byte
	jr	nz,$+4		;Zero => all sectors written
	ld	a,1
	ld	(ssect),a	;Update the sector
	ld	b,1ah		;Postamble length less one
sdlbla:	ld	(hl),0ffh
	djnz	sdlbla		;Write the postamble
	jr	nz,smloop	;Test for more sectors to format
	ld	(hl),0ffh	;First fill byte
	ld	b,0		;Side bit
sdsbit	equ	$-1
	ld	a,(sside)	;Get the current side
	xor	b		;Conditionally switch side bits
	ld	(sside),a	;Update the side byte
	ld	(hl),0ffh	;Write second fill byte
	ld	b,19h		;Preamble length less one
	ex	Af,Af'		;Save the double sided status
sdlblb:	ld	(hl),0ffh	;Write a fill byte
	ld	a,(status)
	and	index
	jr	z,sdlblb	;Wait for the index hole
	ex	Af,Af'		;Recover the double sided status
	jr	z,sdlblc	;Zero => single sided
	ld	a,(iy+2)	;Get the drive pattern
	or	0ch		;Turn off the step command
	and	0fdh		;Turn on head one
	ld	(4005h),a	;Update drive control register
	ld	(hl),0ffh	;Write first preamble byte
	jp	sdlbl3		;Go format the other side
sdlblc:	ld	(hl),0ffh	;Trailing byte
	xor	a
	ld	(de),a		;Turn off write gate
	ld	a,6
	ld	(4006h),a	;Turn off the controller
	ld	a,40h		;Status code
	ret
sdadvt:	ld	a,(strck)	;Get the current track
	inc	a		;Advance track value
	ld	(strck),a	;Update the track value
	ret			;Return with track value
	.dephase
	page
;
;	North Star multi desity formatter routine
;
nsform	equ	$
	.phase	1030h
nsfmt:	ld	a,0
	call	sdrive
	ret	nz
	ld	(ix+0bh),0
	ld	a,(iy+2)
	or	0eh
	ld	(4004h),a
	call	hsync
nsexit:	ld	a,82h
	ret	z
track0:	call	home
	bit	5,(hl)
	jr	z,nsexit
entry:	ld	(ix+0bh),0
	ld	a,(track)
	cp	(iy+1)
	call	nz,seek
	ld	a,(4003h)
	and	40h
	ld	a,90h
	ret	nz
	ld	(ix+0ah),80h
wsect0:	call	hsync
	jr	z,nsexit
	xor	a
	cp	(ix+0ah)
	jr	nz,wsect0
	ld	a,90h
	ld	(contrl),a
	ld	hl,diskd
	ld	c,0
	ld	(ix+9),c
	ld	b,11h
	ld	a,0
den1	equ	$-1
	rra
	ld	a,64h
	jr	nc,cstart
	ld	a,18h
strack	equ	$-1
	rra
	add	a,5
	cp	(iy+1)
	sbc	a,a
	and	10h
	or	24h
	ld	b,20h
cstart:	ld	(4006h),a

zerow:	ld	(hl),0
	ex	(sp),hl
	ex	(sp),hl
	djnz	zerow
	ld	a,(den1)
	or	a
	jr	z,lasts
	ld	(hl),0fbh
	ex	(sp),hl
	ex	(sp),hl
lasts:	ld	(hl),0fbh
	ld	b,5ch
	ld	e,20h
data	equ	$-1
	ld	d,20h
cpdata	equ	$-1
	xor	a
d1loop:	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),e
	xor	e
	rlca
	djnz	d1loop
	ld	b,51h
den2	equ	$-1
	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),d
	xor	d
	rlca
	ex	Af,Af'
	ld	a,e
	ld	(cpdata),a
	ex	Af,Af'
	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),e
	xor	e
	rlca
d2loop:	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),e
	xor	e
	rlca
	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),e
	xor	e
	rlca
	djnz	d2loop
	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),a
	ld	a,(den1)
	or	a
	ld	b,11h
	jr	z,$+4
	ld	b,20h
iloop:	ex	(sp),hl
	ex	(sp),hl
	ld	(hl),e
	ld	a,(status)
	and	index
	jr	z,iloop
	inc	c
	ld	a,0ah
	cp	c
	jr	nz,zerow
	ld	c,0
	ld	a,(nsdsid)
	xor	0
dflag	equ	$-1
	ld	(nsdsid),a
	jr	z,ftdone
	ld	a,(iy+2)
	or	0eh
	and	0fdh
	ld	(4004h),a
	jr	zerow
ftdone:	ld	(contrl),a	;Turn off write gate
	ld	a,40h
	ret
advtrk:	ld	a,(track)	;Get the current track
	inc	a		;Advance track value
	ld	(track),a	;Update the track value
	ret			;Return with track value
track:	0
nsdsid:	0
	.dephase
ecode	equ	$		;End of code marker, stack follows
	ds	30h		;Room for the stack
buffer	equ	$		;Track read buffer

	end