Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!killer!jockc
From: jockc@killer.DALLAS.TX.US (Jock Cooper)
Newsgroups: comp.sys.apple
Subject: Re: Comments on GS/OS
Message-ID: <5666@killer.DALLAS.TX.US>
Date: 28 Sep 88 22:07:52 GMT
References: <6230017@hpindda.HP.COM>
Reply-To: jockc@killer.Dallas.TX.US (Jock Cooper)
Organization: The Unix(R) Connection BBS, Dallas, Tx
Lines: 17

In article <6230017@hpindda.HP.COM> tribby@hpindda.HP.COM (David Tribby) writes:
>A few observations after working with OS/GS for a couple of evenings...
>partitioning. I am *real* curious about one aspect: what is the difference
>between formatting a 3.5 disk as "800K  2:1" and "800K  4:1"?

2:1 and 4:1 are disk interleave values.  The blocks on a track are not numbered
consecutively.  Rather, using a 2:1 interleave, they look something like
0 8 1 9 2 A 3 B ... etc.  4:1 would look something like 
0 4 8 C 1 5 9 D 2 6 A E 3 7 B F ... Interleave gives the CPU time to digest a 
block.  When the CPU asks for another (hopefully consecutive) block, the next
block should be under the read/write head.  2:1 interleave is good for GS/OS, 
since GS/OS is faster than P16 was, it needs less time to process a given block.
P16 likes 4:1.  Hope this all made sense...

Jock Cooper

ihnp4!killer!jockc