[Coco] Disk Drive formatting WAS:quick question
6809er at bjork-huffman.net
Fri Dec 28 13:46:52 EST 2007
On the loaders for my games, did I use an "every other one"
interleaving. But I also change the size of the sectors to not only
speed up the loading of the games but increase the storage on the floppy.
If the sector jumps up form 256 to 1024 then you get an extra 512
bytes per track. (or was it 512 bytes sectors? its been a long
time.) What ever it was you got extra storage per track.
Anyway, the interleave was 1,3,2,4,5. (or 1,3,5,7,9,2,4,6,8 for 512
I'm starting think I used 512 byte sectors. As I said before, its
been a long time.
Oh yes, I do remember loading the whole track at once (into a screen
buffer), tolled the controller to step to the next track. During the
time it took the drive to step I used the time to moved the data to
right place. There was no wasted time loading in the data and the
floppy head just moved right long.
Steve (6809er) Bjork
At 08:50 AM 12/28/2007, you wrote:
>On Fri, 28 Dec 2007, Torsten Dittel wrote:
> > I played around with that on the ATARI ST and didn't only change the
> > sector interleave for one track but as well between the tracks (it
> > wasn't necessary to start with the 1st sector right after the index hole
> > so after stepping to the next track you wouldn't have to wait for the
> > index hole passing by). I called this formatting "spiralization". Since
> > the floppy disks were doublesided, another fixed sector # offset between
> > side 0 and 1 made the disks reading even faster under normal TOS
> > operation. However, I never tried to figure out the optimal "fast read"
> > formatting for the CoCo (DECB or OS-9).
> > Torsten
>It would undoubtedly depend heavily on what step rate the drive was using.
>If you optimized it for the 30 ms step rate that Disk Basic uses, you'd negate
>the advantage of patching Disk Basic for a faster rate. Though I suppose
>you could build a step rate parameter into this hypothetical
>that would adjust the degree of "spiralization" depending on what
>step rate you
>wanted to optimize for.
>Coco mailing list
>Coco at maltedmedia.com
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