[Coco] Sierra Xmas 86 demo

[Stephen H. Fischer]

Hi,

Go to the NitrOS-9 documentation:
http://sourceforge.net/apps/mediawiki/nitros9/index.php?title=NitrOS-9_Technical_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

Bit 2 Track density
0 Single (48 tracks per inch)
1 Double (96 tracks per inch)

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 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