Jun-Sung Kim wrote:
>
> Hi,
>
> Thanks for the answers. And now I'm curious again...
> ...
> Interesting...
> Where I obtain FAT16 file system info? (different part from FAT12)
> I dumped bootsector(?) of FAT16. And I found that the number of
again... read IDEFDISK.TXT :)
In that document there is a complete table with such info...
> sectors for one cluster is 4 instead of 16 for FAT12. Does the entry
> have differnt meaning?
no. The location of the parameters in the bootsector is the same for a
FAT12 and a FAT16 partition. There is only one exception: the size of
the medium. In a FAT12 bootsector only 2 bytes were reserved for that.
That is not enough for a FAT16 partition. In case of a FAT16 partition,
the size is stored in 4 bytes beginning at offset +#020 and the
FAT12sizefield is filled with 0.
About the sectors/cluster field (and other parameters like sectors/FAT):
these depend on the size of the partition you want to make. The routine
for calculating these parameters in IDEFDISK 3.1 is rather complex.
To see the difference between a FAT12 and a FAT16 partition: just check
the number of root directory entries. If the highbyte is #02, then you
got a FAT16 partition. (FAT16 partition are the only ones with 512
directory entries=#0200)
I gathered all my FAT16 info from own research and calculations and some
mails from long time ago on this list. I hardly couldn't find anything
on the internet.
> > by the IDE software: current bios 2.01 'only' support reading/writing of
> > sectors in the first 8 GB range of the device. So if you're using a 10
> > GB harddisk, the last 2GB can't be accessed. The IDEFDISK software which
> > you need to generate partitions, will automatically limit your
> > partitions to the 8GB boundary.
> >
> Is that causes by 24-bit sector number? (512x16M=8G..?)
yes. The internal routines for reading/writing ABSOLUTE sectors use 24
bit sector numbers.
> A document says that DISKIO routine uses 23-bit sector number. Then
> only 4GB is possible to use... Dosen't DOS2 use DISKIO?
4GB is the maximum size for 1 *partition*. You are talking about logical
sectors here. But that is no problem, since the biggest partition, is a
FAT16 partition and these can 'only' be 2GB. So the 23bit limit on
DISKIO is no problem. The several partitions on a harddisk are mapped by
the IDEbios in such a way that they appear as several separate drives on
the DISKIO interface with DOS2. DOS2 doesn't know anything about the
partitioning.
Greetinx,
Jon
****
Problems? contact [EMAIL PROTECTED] See also http://www.faq.msxnet.org/
****
