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From: steve@anasazi.UUCP (Steve Villee)
Newsgroups: net.micro.mac
Subject: Re: Undocumented driver control codes?
Message-ID: <275@anasazi.UUCP>
Date: Wed, 28-Aug-85 18:50:39 EDT
Article-I.D.: anasazi.275
Posted: Wed Aug 28 18:50:39 1985
Date-Received: Sun, 1-Sep-85 13:23:16 EDT
References: <984@wanginst.UUCP>
Distribution: net
Organization: Anasazi, Phoenix Az.
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> In the course of debugging a ramdisk driver, I've found that there are
> several undocumented(?) control codes that the finder uses to interact with
> disk drivers.  The clearly documented ones are:
> 	1 = kill (abort operation in progress and any queued operations)
> 	7 = eject (spit disk)
> 	8 = set tag buffer
> 
> The undocumented ones are:
> 	6 = erase (whole disk?  some fixed number of sectors?  some given
> 			number of sectors?)
> 	$14 = ?
> 	$15 = ?
> 
> Does anyone know what $14 and $15 are supposed to do?  Does anyone know
> *for certain* what 6 is supposed to do?

I have done a bit of poking around myself.  I think code 6 is supposed to
mean format (the entire disk).  There is also code 5, which I think means
verify formatting (on the entire disk).

I base this on a disassembly of the Disk Initialization Package (_Pack2),
which is quite interesting.  The code to handle _Pack2 function 6 (format),
for example, checks to see whether the drive is a Sony drive.  If it is,
it performs the formatting by itself using a bunch of very low level code,
some of which seems to be duplicated out of the Sony driver.  If the drive
is not a Sony drive, then it just does a _Control with csCode = 6.  The
code to handle _Pack2 function 8 (verify) is similar, but in the case of
a non-Sony drive it does a _Control with csCode = 5.

By the way, where is csCode 8 (set tag buffer) "clearly documented"?
There is a section of my Inside Macintosh labelled "Disk Driver", but it
is completely empty!  Do I just have an old/defective copy of IM?  I
would certainly be interested in any available information on the Sony
driver and the general disk driver interface.

--- Steve Villee (ihnp4!mot!anasazi!steve)
    International Anasazi, Inc.
    2219 East University Drive
    Phoenix, Arizona 85034
    (602) 275-0302