*BSD News Article 19619


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Newsgroups: comp.os.386bsd.development
Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!elroy.jpl.nasa.gov!swrinde!menudo.uh.edu!uuneo!sugar!peter
From: peter@NeoSoft.com (Peter da Silva)
Subject: Re: Hard disk geometry translation (was V86 mode ...)
Organization: NeoSoft Communications Services -- (713) 684-5900
Date: Tue, 17 Aug 1993 20:43:10 GMT
Message-ID: <CBx87z.44x@sugar.NeoSoft.COM>
References: <24cc1hINNo8@kralizec.zeta.org.au> <CBo9C6.9ED@sugar.neosoft.com> <24gt3e$gg7@klaava.Helsinki.FI>
Lines: 39

In article <24gt3e$gg7@klaava.Helsinki.FI> torvalds@klaava.Helsinki.FI (Linus Torvalds) writes:
> This is usually not a problem on most systems: almost all BIOSes have a
> "type 47" or whatever that allows you to set your geometry to suit your
> taste.

Well, that's certainly true for modern systems. It's almost always NOT true
for older ones, including mine.

>  - less problems with sharing the disk with other systems: the partition
>    table makes more sense if everybody agrees on the layout of the disk. 

The only thing I have that runs DOS on a regular basis is my Amiga 3000,
and that's emulating the hardware. Less virus worries that way, too.

In any case, you can do what System V does: let the O/S use translated or
untranslated code on a case by case basis. That's the high quality solution.
Unlike some folks here, I don't automatically go "Ick. System V. Must be
the wrong thing to do."

>  - I personally think the "translation overhead" mentioned by some folks
>    as a source of inefficiency for the filesystems (either due to the
>    controller getting slower due to translation or due to the fs not
>    knowing about the real geometry) is mostly a load of bull-sh*t.

Well, my Miniscribe 9380E got quite a bit faster when I turned translation
off. That might have been due to there being less fragmentation after I
reloaded, but I don't think so... I hadn't been using it much.

>  - parly the same as the above: new drives usually have a variable
>    number of sectors anyway in reality, so trying to use a "native
>    mapping" is definitely not worth it.

For those drives, turn translation on. Make it the default. That's fine. But
it's gotta be able to turn off, too.
-- 
Peter da Silva.  <peter@sugar.neosoft.com>.
 `-_-'   Hefur thu fadhmadh ulfinn i dag?
  'U`    
"Det er min ledsager, det er ikke drikkepenge."