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From: csg019@cck.cov.ac.uk (-~=Zaphod=~-)
Newsgroups: comp.sys.amiga
Subject: Re: MFM coding/protection.
Message-ID: <1990Dec5.114746.1887@cck.cov.ac.uk>
Date: 5 Dec 90 11:47:46 GMT
References: <1990Nov27.113820.28055@cck.cov.ac.uk> <1990Nov28.163130.29457@batcomputer.tn.cornell.edu>
Organization: Coventry Polytechnic, Coventry, UK
Lines: 57

In article <1990Nov28.163130.29457@batcomputer.tn.cornell.edu> riley@batcomputer.tn.cornell.edu (Daniel S. Riley) writes:
>[ 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
>
Thank you for your constructive critisism. I know this code is DIRTY and
could be modified to work no problems (using you either your method, or
a quicker trip to the $dff006 register, taking in to account a PAL or NTSC
system.)

Please don't try to tell me how to code, i've been at 68k for 4 years now
and i know my weaknesess better than anyone else. It was meant as a demo
to give info on decoding and disk layout, NOT to be taken as 100% perfect.


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