From owner-freebsd-chat  Mon Nov 25 20:06:30 1996
Return-Path: owner-chat
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.5/8.7.3) id UAA05680
          for chat-outgoing; Mon, 25 Nov 1996 20:06:30 -0800 (PST)
Received: from hill.gnu.ai.mit.edu (hill.gnu.ai.mit.edu [128.52.46.43])
          by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id UAA05618
          for <chat@FreeBSD.org>; Mon, 25 Nov 1996 20:05:14 -0800 (PST)
Received: by hill.gnu.ai.mit.edu (8.6.12/8.6.12GNU) id XAA10823; Mon, 25 Nov 1996 23:03:52 -0500
Date: Mon, 25 Nov 1996 23:03:52 -0500
Message-Id: <199611260403.XAA10823@hill.gnu.ai.mit.edu>
From: Joel Ray Holveck <joelh@gnu.ai.mit.edu>
To: msmith@atrad.adelaide.edu.au
CC: msmith@atrad.adelaide.edu.au, terry@lambert.org, grog@lemis.de,
        chat@FreeBSD.org, smut@clem-162.dorms.tamu.edu
In-reply-to: <199611260210.MAA00537@genesis.atrad.adelaide.edu.au> (message
	from Michael Smith on Tue, 26 Nov 1996 12:40:17 +1030 (CST))
Subject: Re: SCSI A/V drives
Sender: owner-chat@FreeBSD.org
X-Loop: FreeBSD.org
Precedence: bulk

   > Okay, understood... I hadn't realized that the recal was a
   > time-consuming process.  Why does the drive logic not continuously
   > update the thermal expansion factor it uses, each time it seeks?
   Some do; it's an expensive process though, and often servo logic
   doesn't have the grunt for it (think 'low cost').

Expensive in terms of time (and where is it spent? Calculations or
head seeks?) or in terms of circuitry or what?

Is this type of logic usually handled by a controller with a PROM or
by custom circuitry?

Thanks,
Joel