Path: utzoo!attcan!uunet!bu.edu!rpi!zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!rutgers!cbmvax!cbmehq!cbmger!peterk
From: peterk@cbmger.UUCP (Peter Kittel GERMANY)
Newsgroups: comp.sys.amiga
Subject: Re: Reading 1581 disks
Message-ID: <450@cbmger.UUCP>
Date: 27 Sep 90 07:36:06 GMT
References: <2041@lpami.wimsey.bc.ca>
Reply-To: peterk@cbmger.UUCP (Peter Kittel GERMANY)
Organization: Commodore Bueromaschinen GmbH, West Germany
Lines: 21

In article <2041@lpami.wimsey.bc.ca> lphillips@lpami.wimsey.bc.ca (Larry Phillips) writes:
>In <439@cbmger.UUCP>, peterk@cbmger.UUCP (Peter Kittel GERMANY) writes:
>>
>>Is this REALLY true? With all the track-to-track read speed changes in
>>the 1541 format?
>
>If memory serves, there were no track to track red speed changes... only a
>smaller number of sectors per track as you approached the center of the disk.

If you have different numbers of sectors on different tracks, then the
relation between bits and rotation angle varies. To work this out, you
have 2 choices: a) vary rotation speed with the track (I think this
does the Mac), b) vary write density. And this is done in the 1541 and
all the CBM floppies. Yes, this is done in zones, in total there are
only 3 or 4 different values.  

Nice to hear of another guy who has programmed in those Old Days.

-- 
Best regards, Dr. Peter Kittel  // E-Mail to  \\  Only my personal opinions... 
Commodore Frankfurt, Germany  \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk