Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!newstop!sun!pepper!cmcmanis
From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga.tech
Subject: Re: amiga disk drives ...
Message-ID: <113999@sun.Eng.Sun.COM>
Date: 6 Jul 89 18:40:15 GMT
References: <4285@merlin.usc.edu>
Sender: news@sun.Eng.Sun.COM
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 42

In article <4285@merlin.usc.edu> wdao@castor.usc.edu (Walter Dao) writes:
>The amiga disk drive as any other drive can only write a given number
>of WORDS (2 bytes) on any single track.
>  I can write ... $31d8 (+/- 2) bytes.
>  I have encountered disks ... had 320a bytes ... or 30ca .

One of the more common copy protection methods. The Amiga can synchronize
to a slightly faster data clock rate and read more bytes of the disk than
it can write to them. The copy protection comes from the fact that an 
unmodified Amiga drive cannot write that same data, hence can't make a 
copy. 

Seems like Walter has clearly taken up the challenge of writing a protected
disk copy program ala NIB or Marauder. Usually this is a good project since
it will teach you a lot about disk formats, copy protection, and how data
can and cannot be stored on magnetic media. [ If you use this knowledge to
pirate programs then you will be considered scum until you repent. ]

>now my question : how can I slow/speed up the motor (?) write spead (?) 
>of my disk drive so that I can have more/less bytes storable on a track

Answer : Not easily. Try taking the drive out of your machine and twiddling
	with the speed potentiometer(sp?). Actually, when embarking on an 
	endeavor such as yours, the proper equipment is essential. Pick up
	a logic analyzer and an oscilloscope, and connect them to an "exposed"
	drive (out of the case). That will let you monitor most anything.

On a slightly different but similar note :

	CADVision has Designer X-Cad out for $120 at my local dealer. This
	seems to be 100% of X-Cad but with a new label (including the 
	Commodore chicken head ?!?!) It is also dongle protected. I want
	to buy this program, but won't until I have a patch to eliminate
	the dongle requirement. If anyone knows how to do this send me
	some mail, thanks. Music-X is _not_ copy protected and I appreciate
	that immensely. 


--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.
"A most excellent barbarian ... Genghis Kahn!"