Path: utzoo!yunexus!stpl!yugas!julius
From: julius@yugas.UUCP (Julius OKLAMCAK)
Newsgroups: comp.sys.atari.st
Subject: Drive B Step Rate
Message-ID: <809@yugas.UUCP>
Date: 4 Jan 89 03:13:56 GMT
Article-I.D.: yugas.809
Reply-To: julius@yugas.UUCP ()
Organization: C.R.E.S.S., York University, North York, Ontario, Canada, M3J 1P3.
Lines: 92

In article	<8812271702.AA11024@ucbvax.Berkeley.EDU>,
		aking@BBN.COM (Allen King) writes:

>   Speaking of "legal official atari sanctioned" ways, how do you set the step
>rate of one floppy (e.g. drive B) to 6ms. I know how to do it by modifying
>an unpublished address, and there is a call to set the default step rate. But
> [rest deleted]

Awhile back I hacked together a step rate program that tested the TOS version
number and then set drive B to a 6 ms step rate.  Last week I found out that
TOS 1.4 will have an official call to legally :-) set the step rate...

Anyway, here follows the (educational use only :-) 68000 source to my step
rate program:

*************************************************************************
*									*
*	Set Drive B Step Rate				08/03/88	*
*									*
*	J. Oklamcak @ Atari (Canada) Corp.				*
*									*
*************************************************************************

		text

		pea.l	SetRate			; Set drive B step rate
		move.w	#38,-(sp)
		trap	#14
		addq.l	#6,sp

		tst.b	SetFlag			; Check rate set flag
		bne.s	SetOk
		beq.s	NotOk

SetExit:	clr.w	-(sp)			; ...done...
		trap	#1

SetOk:		pea.l	RateSet			; Step rate set
		move.w	#9,-(sp)
		trap	#1
		addq.l	#6,-(sp)
		bra.s	SetExit

NotOk:		pea.l	IsNotSet		; Step rate not set
		move.w	#9,-(sp)
		trap	#1
		addq.l	#6,-(sp)
		bra.s	SetExit


SetRate:	move.l	$04F2,a0		; Base address of OS
		move.w	2(a0),d0		; Get OS version number
		lea.l	TOSVers,a0		; TOS version numbers
		lea.l	RateAddr,a1		; Step rate addresses

FindTOS:	move.w	(a0)+,d1		; Get version number
		bne.s	TestTOS			; Test version number
		sf.b	SetFlag			; Step rate not set
		rts

TestTOS:	move.w	(a1)+,a2		; Get address of step rate
		cmp.w	d0,d1			; Test TOS version number
		bne.s	FindTOS			; Next version number...

		move.b	#0,(a2)			; Set the step rate
		st.b	SetFlag			; Step rate is set
		rts

		data

TOSVers:	dc.w	$0100			; $0A0D
		dc.w	$0102			; $0A53
		dc.w	$0104			; $0A53
		dc.w	0

RateAddr:	dc.w	$0A0D			; 1.00
		dc.w	$0A53			; 1.02
		dc.w	$0A53			; 1.04

RateSet:	dc.b	$0D,$0A
		dc.b	"Drive B step rate : 6 ms"
		dc.b	$0D,$0A,0

IsNotSet:	dc.b	$0D,$0A
		dc.b	"Drive B step rate not set : OS version unknown"
		dc.b	$0D,$0A,0

		bss

SetFlag:	ds.w	1

		end