ORG 100H
		.z80

rstchan	equ	50h
drive0	equ	0h
sel	equ	0
stepl	equ	1
steph	equ	2
cmnd	equ	0bh
status	equ	0ch
stepin	equ	0h			;constant to go to track 152, drive 0
stepout equ	10h			;constant to go to track 0, drive 0
step	equ	06h
attn	equ	55h
maxtrac	equ	09bh			;number of tracks for ST-506
cpm	equ	0			;warm boot
channel	equ	cmdchan
stepdeì eqõ     01cè                    ;steð delaù foò  ST-506
settle  equ     0                       ;head settle for ST-506  
secsiz  equ     7                       ;1024 byte sectors 
reset	equ	54H
arg0    equ      07            		;command arguments  
arg1    equ      08            		;command arguments  
arg2    equ      09            		;command arguments  
arg3    equ      0ah           		;command arguments  
cnsts   equ     04h                     ;load constants cmd


init:	ld	sp,100h			
	ld	b,0
	ld	c,10H
	ld	hl,channel
	ld	(rstchan),hl
	ld	(channel + 0dh),hl	;link field init
	xor	a
	ld	(rstchan + 2),a		;channel address @ 80h
	ld	(channel + 0fh),a	;link field init
	out	(reset),a

init1:  ld      ix,channel
        ld	(ix + sel),a		;zero select byte
	ld	(ix + stepl),a		;zero steps
	ld	(ix + steph),a		;zero steps
	ld      (ix + arg0),a		;zero cyl argument
        ld      (ix + arg2),a  		;zero head settle
        ld      a,stepdel    		;3 ms steps
        ld      (ix + arg1),a
        ld      a,secsiz    
        ld      (ix + arg3),a  		;1024 sectors
        ld      a, cnsts		;load constants cmd
        ld      (ix + cmnd),a
        call    loop

loop1:	dec	c			;wait for controller to reset
	jr	nz,loop1

start:	ld	a,step
Š	ld	(ix + cmnd),a		;step command
	ld	a,0
	ld	(ix + status),a		;null the status
	ld	a,0ffh
	ld	(ix + stepl),a
	ld	(ix + steph),a	
	ld	a,stepout
	or	b			;or in the drive number
	ld	(ix + sel),a		;send it home constant
	call	loop


goout:	ld	a,stepin		
	ld	(ix + status),a		;null the status
	or	b			;for each drive
	ld	(ix + sel),a		;constant to seek in
	ld	a,maxtrac		;09bh for seagate
	ld	(ix + stepl),a
	xor	a
	ld	(ix + steph),a
	call	loop
	inc	b
	bit	2,b
	jr	z,start			;once for each drive
	jp	cpm			;warm boot

loop:	out	(attn),a		;kick controller
	ld	hl,0
	ld	c,10h			;1 minute to respond

loop0:	ld	a,(ix + status)
	cp	0ffh
	ret	z
	dec	hl
	ld	a,h
	or	l
	jr	nz,loop0
	dec	c
	jr	nz,loop0 
	jp	cpm

cmdchan equ    $ 

	end