Path: utzoo!mnetor!uunet!ingr!b11!jim
From: jim@b11.UUCP (Jim Levie )
Newsgroups: comp.sys.amiga
Subject: Amiga 2090 Controller Questions
Message-ID: <229@b11.UUCP>
Date: 30 Jan 88 07:48:39 GMT
Organization: Far from the halls of Amber
Lines: 50
Keywords: 2090 Controller

I suppose that this is primarily directed at the CATS folks, but somebody
else may also know the answers.

First of all where does the limit of 17 blocks (sectors) per track come from?
Is it a hardware consideration in the ST506 circuitry or a software limit in
the driver?  I tried an Atasi 3046 with the 2090, which works at 17 sectors
per track, but not above.  The Atasi has over 10K bytes per track which should
allow 20 sectors.

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?

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'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.

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.  A SCSI adapter will need the drive geometry to be set up before
accessing the drive and I don't think that the current version of prep or
hddisk.device are capable of doing this.  Will this restriction be removed
when the Fast File System is released, or have I missed something?

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?





-- 
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 Jim Levie   REMTECH Inc  Huntsville, Al 
 The opinions expressed above are just that.
 Ph.    (205) 536-8581               email: uunet!ingr!b11!jim