Path: utzoo!mnetor!uunet!husc6!rutgers!lll-lcc!lll-tis!ptsfa!well!dsmall
From: dsmall@well.UUCP (David Small)
Newsgroups: comp.sys.atari.st
Subject: Re: speeding floppies?
Message-ID: <4884@well.UUCP>
Date: 2 Jan 88 09:43:43 GMT
References: <8712222223.AA29981@ucbvax.Berkeley.EDU>
Reply-To: dsmall@well.UUCP (David Small)
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 37


In the referenced article, there's much discussion about speeding
up floppies from Michael Stein.

There's no point in using a disk with interleave on it on the ST; the
ST is more than capable of 1:1 reads and writes. Since the ultimate
limiting factor is the head rubbing against the media at a certain speed,
and the ST is doing r/w as fast as physically possible, there's no
possible gain there.
  It is dangerous to remove the seek verify bit in the manner you have.
Let's say you step to a new track. The head rattles back and forth
awhile as it settles. During that time it is reading well enough to
return track dta to the controller, yet the head is still wobbling. If you
try a sector write, which lasts 16 msec, during this time, it's written in
a yo-yo pattern on the disk -- and is often unreadable the next time.
  This comes from hard experience; I did this on the Magic Sac Motivator, and
could consistently kill the first sector of each track. Weird, but true.
  You're right that a full disk rev is saved. A better way is to just twist
the track two sectors around, leaving one sector (#9 or 10) for the settle
time and one sector (#8 or 9) for the seek verify. Then you don't lose any
time at all track to track, and keep full compatability with unmodified
ST's. That's how we did Twister.
   As for using the index pulse as the delay time for seek, well, maybe. On
9 sector tracks you'll get away with it.. remember, 16.667 millisec per sector.
On 10 sector tracks you won't, there is no room. But worse, the step only
happens on the next-sector-read command, which may take awhile to
happen, all of which time the disk is spinning.
  Since you're stuck with 30 msec head settle, and lots of machine have
seek-with-verify, I think it's the optimal solution to twist the track by 2.
You just can't physically get data off multiple tracks any quicker without
speeding up the RPMs of the drive.

  .. perhaps we should plug it into a 220 Volt outlet?

 -- Thanks, Dave

dave small/bottlewasher/data pacific inc