[Coco] Sierra Xmas 86 demo

[Gene Heskett]

On Monday 10 December 2012 00:39:44 Stephen H. Fischer did opine:

> Hi,
> 
> Go to the NitrOS-9 documentation:
> http://sourceforge.net/apps/mediawiki/nitros9/index.php?title=NitrOS-9_T
> echnical_Reference#Identification_Sector_.28LSN_0.29
> 
> hit f3 in IE and search for DD.FMT, the third occurrence.
> 
> -------------------------------
> The format attributes (DD.FMT) are these:
> 
> Bit 0 Number of sides
> 0 Single-sided
> 1 Double-sided
> 
> Bit 1 Density
> 0 Single-density
> 1 Double-density

This is data density, nothing to do with track density.
> 
> Bit 2 Track density
> 0 Single (48 tracks per inch)
> 1 Double (96 tracks per inch)
> 
Sorry, no.  There is no double track density in any 3.5" drive.

> DNS=1 means Double Density, 48 TPI
> DNS=3 means Double Density, 96 TPI.
> 
> All OS-9 disks are Double Density. FLEX always had Track 0 Single
> Density, the rest of the tracks Either Single or Double depending on
> what Track 0 said.
> 
> 3.5" drives are 96 TPI

No, they are 135 tpi.  No variations.

> and  my 5.25" drives were 96 TPI also.
> They did not  last very long as 1.3 meg ? drives soon replaced them.
> 
> No, I do not know why this does not compute. Bit 0, the number of sides
> is moved elsewhere I suspect and DNS I cannot find???
> 
> DNS=3 was what I used for both 3.5" and 5.25", when I got a 3.5" drive I
> did not need to change /D0 or was it /D1.
> In any case, the switch to swap /D0 and /D1 as added quickly.
> 
> SHF
> 
> 
> 
> ----- Original Message -----
> From: "Bill Pierce" <ooogalapasooo at aol.com>
> To: <coco at maltedmedia.com>
> Sent: Sunday, December 09, 2012 7:37 PM
> Subject: Re: [Coco] Sierra Xmas 86 demo
> 
> > Stephen...
> > Not sure about the 80 trk 5.25 but I think it's supposed to be dns=3
> > also. I think this applies to any double stepping drive and 80 trk
> > 5.25 fits the bill so let me rephrase that
> > 
> > SSDD - DSDD Single stepping drives should be dns=1 (35trk & 40 trk)
> > DSDD Double stepping drives should be dns=3 (80trk)
> > 
> > That should cover it better.
> > 
> > I think it has something to do with the timing in the step rate of the
> > double stepping drives. Gene could probably clarify this as he seems
> > to be "Drive man" and knows more about stepping motors than most.
> > 
> > Bill P
> 
> --
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> Coco at maltedmedia.com
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Cheers, Gene
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