Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!bsu-cs!cfchiesa
From: cfchiesa@bsu-cs.bsu.edu (Christopher Chiesa)
Newsgroups: comp.sys.atari.8bit
Subject: Densities and their Interactions
Keywords: 1050 US Doubler Enhanced Density Double Density
Message-ID: <8057@bsu-cs.bsu.edu>
Date: 4 Jul 89 21:12:57 GMT
Organization: CS Dept, Ball St U, Muncie, IN, USA
Lines: 41

Hello all...  

   Have finally dug up a copy of Atari DOS 2.5, and begun using the two 
Atari 1050 drives I recently bought (separately) to replace my decrepit and
annoying single-density-only Percom drive.  Am running into certain phenome-
na which I think I've heard a little about, but am not entirely clear on, 
and am without documentation for DOS 2.5 (I got it on a disk with Atari
Protection Techniques book, NOT with either of my 1050's.)

   System consists of two Atari 1050 drives: Drive 1 sports a 'US Doubler'
chip, Drive 2 is unmodified as far as I know.

   I find that I can't reformat an enhanced-density disk into Single density
from certain programs (e.g. Bob Puff's Disk Communicator, which insists on
doing Enhanced density after presenting me with a choice between Single and
Enhanced), but that I seem to be able to do it okay from DOS 2.5 (the menu).
Additionally, I seem to be able to READ Enhanced Density MOST of the time
on the US-Doubler drive, but not ALWAYS, and can apparently NOT WRITE it at
all.  All of this is subject to the strong possibility of insufficient evi-
dence, but I'm in a hurry to just get someone to send me the Real Story...

  Basically, I'd love to see some technical stuff about the software support
for the US Doubler, e.g. what CIO or SIO command(s) must be sent to get into
and out of Single, Double, and Enhanced (if it coexists on this drive) densi-
ties, at will, for formatting.  (I already understand that READING the disk
AUTOMATICALLY configures the drive to READ the proper density.)

  Ditto for Atari DOS 2.5, including extensions to DOS 2.0 XIO (CIO) calls
and parameters for handling the "additional sectors," Enhanced density, et
al.

  I realize that this is a lot to ask for, and a bit vague at that, but I'm
dying for SOME information; I've got all this hardware and only REALLY know
what's what when I ignore it all and use single-density only.  

  Thanks in advance, Oh Net Gurus!

     Chris Chiesa
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