Path: utzoo!mnetor!uunet!cbmvax!gunther
From: gunther@cbmvax.UUCP (Ed Gunther QA)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga 2090 Controller Questions
Message-ID: <3260@cbmvax.UUCP>
Date: 3 Feb 88 17:31:02 GMT
References: <229@b11.UUCP>
Reply-To: gunther@cbmvax.UUCP (Ed Gunther QA)
Organization: Commodore Technology, West Chester, PA
Lines: 87
Keywords: 2090 Controller

In article <229@b11.UUCP> jim@b11.UUCP (Jim Levie ) writes:
> Since one has to to create a mount list entry for RESn: before running prep
> why does prep need the number of heads, sectors, low and high cylinder, etc?
> Seems to me that the only question prep should really need to ask concerns
> precomp cylinder and parking.  Also the mountlist entries allow the
> specification of memory type, but prep doesn't.  I would assume that prep
> sets the buffer memory type to public, is this correct?
> 
     First, do realize that all the information in the mountlist is not
     necessarily supported.  Also, what version of prep do you have?  As
     far as I know the latest version is 33.19.  It does not ask for
     detailed drive information if you are using a supported drive, only if
     you specify drive type 0, namely user defined.  Yes, the buffer memory
     type specification has no effect on where the buffers actually get 
     located.  The hddisk.device uses whatever is next.  You can get the
     buffers in fast ram by running slowmemlast before binddrivers.

> Why will format guru the system if one accidentally asks to format more
> cylinders than the disk has?  Seems to me that, at least for ST506 devices,
> the hardware should detect an attempt to seek past the last cylinder and
> the driver should gracefully handle it.
> 
     I have done this, strictly by accident of course, but I do not recall
     guruing the system.  What does happen is the format locks up the CLI
     in which is it running, which I'll agree is not great either.

> I'm not sure if this has already been answered or not.  When an ST506 disk
> is formatted by AmigaDOS do bad blocks get mapped out, and if so how?  The
> possibilities that occured to me are that format could just chain out the bad
> blocks or there could be a replacement table.  While the disk was formatting
> it seems occasionally to retry, I assume that this was bad block detection.
> Prep asks about manual bad block entries, but I don't know how one would
> have the information without some type of 'bad block' utility.
> 

     The AmigaDOS format exercises each block something like five times during
     the format (so like this is why it takes so long compared to the
     formatting of as similar drive on a PC) and maps out any bad blocks and
     assigns replacements up to 126 bad blocks. The occasional retries of
     which you speak are undoubtably bad block retries as the system makes
     sure a block really is bad.  Yes, an entire drive bad block test utility
     might be useful and forthcoming one of these days,
     but every drive is tested by the
     manufacturer for defects and has a list of defect information on the drive.
     This information, namely the cylinder, head, and offset of these known
     defects is precisely the information which prep asks for when entering
     bad block data.  A "good" bad block utility would allow one to specify
     the physical setup of a drive, i.e. number of head, cylinders, ect., and
     allow one to determine the block number of a defect given the cylinder,
     head, and offset as well as the inverse, the cylinder, head, and offset
     from the block number.  I have written some lousy routines that do this
     for a four head drive which may be real easy to fixup.  Dare I ask if
     anyone is interested in these?  Let me know.  I'd rather send them by
     mail so I don't have to be too embarrassed.

> A little experimentation with an embedded SCSI disk drive (Rhodime 652) leads
> me to belive that it is not possible to use SCSI adapters with the current
> hddisk driver.

     I'm not sure I'm following this one.  Is this just a scsi drive or a
     scsi to ST-506 adapter hooked up to an ST-506 drive or what.  Send me some
     mail on this, okay?
> 
> The 2090 manual is fine for installing and setting up the controller and
> drive, however there isn't any information about the Amiga Interface to the
> controller in the manual (csr's etc).  Any chance that this info is going to
> be released?
> 
     Find out from CATS about this.  There is information about the hardware
     in the C-A A500/A2000 Technical Reference Manual.  As far as the software
     interface goes, there must be something developers are getting about this,
     but I haven't seen it.
> 
> =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
>  Jim Levie   REMTECH Inc  Huntsville, Al 
>  The opinions expressed above are just that.
>  Ph.    (205) 536-8581               email: uunet!ingr!b11!jim


-- 
(((((((((()((((((((())(((((((()))((((((())))(((((()))))((((())))))(((()))))))
  __  Ed Gunther              COMMODORE AMIGA TEST ENGINEERING
 /        /\                  "The LAST line of defense, if "THEY" let us!"
<    ==  /__\                 UUCP  ...{allegra,ihnp4,rutgers}!cbmvax!gunther
 \__    /    \                PHONE 215-431-9356 (life or death only please!)
      "Disclaimer, heck no!  NOooo PROBLEM.  You have myyyy word on it."
(((((((((()((((((((())(((((((()))((((((())))(((((()))))((((())))))(((()))))))