[Coco] Nitr0S-9 question

[Gene Heskett]

On Tuesday 14 August 2007, Becker, Gary wrote:
>I do not believe it.sas and dd.bit have any connection. But it really
>does not matter. I am trying to write the boot track to track 34 on a
>disk image using os9gen. I believe because the allocation bit map is
>greater than 1024 bytes, os9gen is failing. By using the cluster size
>option in format when I create the image, dcheck says the drive file
>system is not valid.
>
>I guess I will have to create my own utility to do what I need done.
>
Personally, I believe you may be barking up the wrong tree.  The boot track, 
nominally track 34 on a floppy, or tracks 128 or 129 on a B&B system, is 
absolutely fixed at $1200 bytes for its size, which is a full track of 18 256 
byte sectors and 18*256=4608 bytes.

dcheck, unless its been worked on, is I believe hard coded for DD.BIT=1, so it 
may be that anything else is an error.  I've not been able to make it work 
with my newer 1GB seagate drive.

DD.BIT and IT.SAS are two entirely different animals.  DD.BIT tells rbf.mn how 
many sectors equal a 'cluster', and one cluster is represented by one bit in 
the allocation map.  The size of the allocation map, aka the FAT, does have a 
65535 byte limit, and this is what limits stock os9's ability to handle hard 
drives with DD.BIT=1, which in turn limits the drive to a hair over 132 
decimal megabytes.  If DD.BIT=2, then 256 binary megabytes can be handled.  
For DD.BIT=4, then 512 megs, 8=a gigabyte etc etc.

IT.SAS is the value, in 'clusters' that will be initially requested when a 
file is opened for writing.  You can control file fragmentation with this 
parameter.  With larger drives its quite common to permanently set that to 
$20, or maybe even to $FF if DD.BIT=1.  On larger drives, where DD.BIT might 
be 8-16-32-64, then this becomes much less important because DD.BIT will 
expand the sector counts in the cluster for you.

But this doesn't mean the file will take up that much storage space as the 
file closing routines will correct the FAT to the number of 'clusters' the 
file actually uses.  If for instance, DD.BIT=32 on a larger multigig hard 
drive, then it is true that a 1 byte file will be assigned 32 sectors 
minimum.  That becomes pretty much a machs nichs point though when you have a 
drive that big.

Describe again, the results you are getting when you run os9gen.

-- 
Cheers, Gene
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