From: Jim Brain (brain_at_jbrain.com)
Date: 2007-12-31 19:54:02
Ruud@Baltissen.org wrote:
> Hallo Jim,
>
>
>
>> Still, the closer you can keep the FS to CBM specs, I think the better.
>>
>
> Then I take this as an shameless opportunity to promote my own LBA system
> :)
>
> - instead of two bytes it uses four bytes to link to the next system. Four
> bytes minus one bit support up to one TeraByte!
>
Sounds great
> - it uses a BAM but without the 'free sectors/track'-byte. The BAM only
> keeps record of what sectors are free or not.
>
Not sure of the specifics, but sounds fine to me.
> - a directory record looks the same as the original one except four link
> bytes except two.
>
Great.
> - very first sector contains some system info, like the diskname, disk
> size, size of a sector and the start sector of the directory
> - the BAM starts at the second sector
> - the directory start after the BAM
>
As stated before, I'd prefer to see the drive contain a std IDE boot
sector (with partition info), and put this stuff at the sector noted by
the partition info.
On the system-info sector, I'd be happy to look at 0x83, FAT, IDEDOS,
etc. to come up with a common FS-boot block if you want.
> My LBA system can support 256 and 512 bytes sized sectors: if the MS bit of
> the 4th byte of the link is set, then this sector is the last sector of a
> file. The first byte, in case of a 512-bytes sized sector the second byte
> as well, tells the system how many bytes of this sector are used.
>
I'm assuming you're talking bit 31 of the link, right? Hehe, that
means, of course, that one cannot use a sector above 1TB :-) no worries
here. The only practical way we'll get there is if someone creates a
partition on a >1TB disk near the end. 1TB disks being so common and
all, in PATA format...
> I started with removing references to the second drive. I also want to
> remove all references to the disk ID. As I cannot swap a disk, why would we
> need a disk ID? Showing the directory, the first line will display:
>
On the disk, I think that is fine. However, I would still leave a spot
on the DIRectory block for the ID and DOS-type (2A), in case someone
wants to modify them.
> 0 "DISKNAME " X-IDE
>
> 'DISKNAME' can be changed. Formatting of the disk can be done with and
> without the ID option. With ID the system only accepts the characters 'ID'.
> This because formatting a real disk will take quite some time. You can
> compare it with the quick option for DOS format.
>
> When writing this, I already removed the write protection routines. But it
> just occurred to me it could come in handy. Your oppinion, please!
>
I'm not sure I understand this. You mean for "locked" files (>PRG) and all?
For my part, I don't have X-IDE HW as yet, but I'm trying to finish my
LFN/FAT16-32 support in uIEC, so I at least know what one needs to do to
maintain the FAT FS integrity. (Reads are easy, and I got them
finished, writes are another story, of course)
Jim
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