[Coco] Issues with NitrOS9 build

Sun Jan 26 01:46:56 EST 2014

On Sunday 26 January 2014 01:32:57 Bill Pierce did opine:

> Bob, on 3.2.9, I cannot read any disk with DNS=3 unless the disk was
> formatted that way, Then that descriptor will ONLY read disks formatted
> with DNS=3. I have to dmode to DNS=1 to read "average" disks. If I
> remember right, Gene explained (in detail) here on the list why no Coco
> disk should use DNS=3 except maybe the 5.25 80trk 720k disks(??).

No "maybe" about it, they are the exception.  Setup that way, then you 
folks who have only one of each drive type, can put a disk that was 
formatted as a 48 tpi disk, in this 96 tpi drive and read it because the 
heads will be double stepped, thereby staying centered on the 48 tpi track.

We have been able to do that for years, but until this latest patch is 
applied, you have always been able to write to the disk too.  But the 96 
tpi head doesn't fully erase the full width of the 48 tpi track, so when 
you put that 48 tpi disk back in a 48 tpi drive, you have both the old 
signal and the new on on those tracks that were written.  The crosstalk 
confuses the wider read head, and the disk is essentially trashed.  With 
luck you might be able to put it back in the 96 tpi drive, and back it up 
to another 40 track disk inserted into the 48 tpi drive.  But due to poor 
lube on the slide rails that can cause slight positioning errors, it isn't 
a 100% guarantee that it will work.  So the best way to preserve the disk 
data in that situation, is to deny the write that would destroy it.  That 
is what this latest patch will do once its applied, and it will fix 
additional bugs that can be the result of the processes memory map when its 
forked, scribbling on the DP register if regs.u is <>0000h at fork time.

> 5.25 35/40trk 180k/360k & 3.5 80trk 720k should be DNS=1.
> The only difference besides the size (CYL & SID) should be 5.25 40trk
> TYP=20 & 3.5 80trk TYP=21

This is also correct.

> 
> Bill Pierce
> "Today is a good day... I woke up" - Ritchie Havens
> 
> 
> My Music from the Tandy/Radio Shack Color Computer 2 & 3
> https://sites.google.com/site/dabarnstudio/
> Co-Webmaster of The TRS-80 Color Computer Archive
> http://www.colorcomputerarchive.com/
> Co-Contributor, Co-Editor for CocoPedia
> http://www.cocopedia.com/wiki/index.php/Main_Page
> E-Mail: ooogalapasooo at aol.com
> 
> 
> 
> 
> -----Original Message-----
> From: Bob Devries <devries.bob at gmail.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Sun, Jan 26, 2014 12:48 am
> Subject: Re: [Coco] Issues with NitrOS9 build
> 
> 
> I am using NitrOS9 v030206 on my coco3. It behaves correctly (IMHO) with
> offset $10 of LSN0 set to $07, and the DMODE (of /D0) DNS=03 TYP=20
> 
> Regards, Bob Devries
> Dalby, QLD, Australia
> 
> ----- Original Message -----
> From: "Bill Pierce" <ooogalapasooo at aol.com>
> To: <coco at maltedmedia.com>
> Sent: Sunday, January 26, 2014 3:13 PM
> Subject: Re: [Coco] Issues with NitrOS9 build
> 
> > Bob, are you pulling from the "default" now? as that is the new
> > current. The lwtools branch is now the old.
> > 
> > 
> > Bill Pierce
> > "Today is a good day... I woke up" - Ritchie Havens
> > 
> > 
> > My Music from the Tandy/Radio Shack Color Computer 2 & 3
> > https://sites.google.com/site/dabarnstudio/
> > Co-Webmaster of The TRS-80 Color Computer Archive
> > http://www.colorcomputerarchive.com/
> > Co-Contributor, Co-Editor for CocoPedia
> > http://www.cocopedia.com/wiki/index.php/Main_Page
> > E-Mail: ooogalapasooo at aol.com
> > 
> > 
> > 
> > 
> > -----Original Message-----
> > From: Bob Devries <devries.bob at gmail.com>
> > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> > Sent: Sun, Jan 26, 2014 12:02 am
> > Subject: Re: [Coco] Issues with NitrOS9 build
> > 
> > 
> > Robert,
> > 
> > The drivers I'm using *should* be the latest. If not, then there's a
> > problem
> > with the NitrOS9 repository, since I did an update right before I
> > built it.
> > 
> > Regards, Bob Devries
> > Dalby, QLD, Australia
> > 
> > ----- Original Message -----
> > From: "Robert Gault" <robert.gault at att.net>
> > To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> > Sent: Sunday, January 26, 2014 12:24 AM
> > Subject: Re: [Coco] Issues with NitrOS9 build
> > 
> >> Bob Devries wrote:
> >>> Well, I got it to work, but I fail to understand why.
> >>> 
> >>> I changed offset $10 (DD.FMT) in LSN 0 from $07 to $03, and it boots
> >>> correctly.
> >>> 
> >>> That change makes the disk a 48TPI instead of 96TPI.
> >>> 
> >>> Why does the TPI setting have *any* effect on the operation
> >>> especially in
> >>> an
> >>> emulator. *something's* not right here.
> >>> 
> >>> Regards, Bob Devries
> >>> Dalby, QLD, Australia
> >> 
> >> Bob,
> >> 
> >> I think you have an intermediate update of NitrOS-9. Some changes
> >> have been made to rb1773 intended to prevent problems writing to
> >> disks formatted differently from what a specific floppy drive can
> >> handle. Basically a mismatch between disk format and descriptor
> >> values. You seem to have created 96tpi disks without having the
> >> newest rb1773 driver and that is preventing you from reading the
> >> disks.
> >> 
> >> I just tested both MESS and VCC using the newest rb1773 with both
> >> DD.FMT 48tpi and 96tpi and the disks boot correctly.
> >> 
> >> I had thought the repository was updated for the new rb1773, so don't
> >> know
> >> why you are having problems.
> >> 
> >> Robert
> >> 
> >> 
> >> 
> >> --
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> > 
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> > 
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Cheers, Gene
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