Path: utzoo!utgpu!watserv1!watmath!att!dptg!ulysses!andante!mit-eddie!bu.edu!rpi!batcomputer!riley
From: riley@batcomputer.tn.cornell.edu (Daniel S. Riley)
Newsgroups: comp.sys.amiga.tech
Subject: Re: MFM coding/protection.
Summary: blech...timing loops.
Message-ID: <1990Nov28.163130.29457@batcomputer.tn.cornell.edu>
Date: 28 Nov 90 16:31:30 GMT
References: <1990Nov27.113820.28055@cck.cov.ac.uk>
Followup-To: comp.sys.amiga
Organization: Cornell Theory Center
Lines: 43

[ warning...flames ahead ]

In article <1990Nov27.113820.28055@cck.cov.ac.uk> csg019@cck.cov.ac.uk (Z*A*P*H*O*D) writes:
[...]
>step_wait	=	3000		Delay for track movement

and

>stepper_delay
>	move.w	#step_wait,d1
>wait
>	dbra	d1,wait

and

>motor_delay
>	move.w	#$b000,d0
>md
>	dbra	d0,md
>	rts

A game programmer fer sure...

Let me guess:  for high performance games on the Amiga, your players
demand that floppy disk access be finely tuned for the 68000--if it
didn't have timing loops, then it just wouldn't be worth playing.

*sigh*

This is the sort of mindless coding that leads to programs that break
on accelerated Amigas for *no* defensible reason whatsoever.  Timing
this with one the CIA timers would take about 6 more lines of
assembly.  Commodore will even tell you how to do it--read Bryce's
article "Amiga Low-Level Disk Access" in AmigaMail volume 1, page
VIII-9.  Using timing loops in floppy access code is just pure
laziness on the part of programmers who can't seem to understand that
the Amiga is not a C-64.  Don't copy this code--get the AmigaMail
article and learn to do it right.

A rare flame from the keyboard of

-Dan Riley (riley@theory.tn.cornell.edu, cornell!batcomputer!riley)
-Wilson Lab, Cornell University