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From: dyer@atari.UUCP (Landon Dyer)
Newsgroups: comp.sys.atari.st
Subject: Re: Why does GEMDOS call Mediach() so often?
Message-ID: <723@atari.UUCP>
Date: Thu, 7-May-87 13:16:48 EDT
Article-I.D.: atari.723
Posted: Thu May  7 13:16:48 1987
Date-Received: Sat, 9-May-87 09:49:31 EDT
References: <8705061403.AA01528@yale-celed.arpa>
Distribution: world
Organization: Atari Corp., Sunnyvale CA
Lines: 23

fischer-michael@YALE.ARPA (Michael Fischer) says:
> Unless there have been substantial changes to the Bios since the
> developer's kit was produced, this is not strictly accurate.
> Mediach() NEVER hits the disk, it only computes and returns a mode:
> 0-safe, 1-unsure, 2-changed.  Rwabs() calls Mediach() and hits the
> disk if 1 is returned, changing the mode to 0 or 2 depending on
> whether the serial numbers match.  If mode=2, Rwabs does not perform
> the I/O but instead returns the media change error (-14).  Getbpb()
> resets the mode back to 0.  Mediach() changes the mode from 0 to
> 1 if a short time (1-2 seconds) has elapsed with no disk I/O and
> the write protect bit has been seen on during that time.  The write
> protect bit goes on whenever a disk is removed from the drive or
> the disk is write protected.

Thank you -- I stand corrected.  Mediach() does NOT hit the
disk.  It is a "cheap" call.  [That'll teach me to answer
questions w/o looking at the source!]

-- 
-Landon Dyer, Atari Corp.	    {sun,lll-lcc,imagen}!atari!dyer
The views expressed here do not necessarily reflect those of	     SEGMENTS
Atari, any of the AI software running on my computers, or my	      ARE FOR
non-existant mother-in-law.					        WORMS