Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!rex!uflorida!haven!umd5!hans
From: hans@umd5.umd.edu (Hans Breitenlohner)
Newsgroups: comp.sys.atari.8bit
Subject: Re: More on SIO
Message-ID: <4781@umd5.umd.edu>
Date: 28 Apr 89 21:13:35 GMT
References: <38936@bbn.COM> <604@eutrc3.UUCP>
Reply-To: hans@umd5.umd.edu (Hans Breitenlohner)
Organization: University of Maryland, College Park
Lines: 16

In article <604@eutrc3.UUCP> rcbamw@eutrc3.UUCP (m.waucomont) writes:
>To make things even worse, a PC drive uses the index hole of a disk to
>determine which sector is the first of a track. The 1050 makes that sector
>(about) twice as long... This should answer your third question...

This is not quite accurate.  The PC (and most other reasonable disks) start
a track at the index mark, write the required number of sectors (with all
the appropriate headers and gaps), and then write a gap until they encounter
the index mark again.  The 1050 does not use the index mark, and therefore
must use a different approach to ensure that the track does not contain
unwanted sector headers:  It writes a very long gap (about 1/4 track, I 
think), then all the sectors, and then stops immediately.  Most of the
long gap gets overwritten.
The resulting track format is almost identical, and most disk drives /
controllers / software drivers can read disks formated by either method
equally well.