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Re: ProDOS misc. questions
In <31FE0E42.4CB6@cardshow.com> Michael writes:
> > > o Why the root directory of a ProDOS volume is limited to 51 files?
> > There's limited space for the root structure.
> Why this root structure has to fit entirely into Block 2?
Actually, the root directory has more than just block 2. There are 4 blocks
with 13 directory entries each = 52 files total.
(One of them holds the volume name.)
> > To overcome this limitation,you'd have to rewrite about everything.
> I don't have time nor knowledge to do that.
I didn't ask the question :-)))
> If I'm good at computing, 8GB (GygaBytes) maximum volume size is =
> attained with a 24-bit addressing mode, isn't it?
Ooops, looks like I'm PRETTY wrong. Yes, you're right!
I was mixing up standard and extended SmartPort protocols. The standard
protocol supports volumes up to 8Gb while the extended can go up to this
terabyte thing.
Sorry for the confusion..
> An Apple II expert could then hack a new 24-bit addressing version of =
> ProDOS, couldn't he? Is there a need for this?
As I said before, you can't simply change everything from 16bits to 24 or even
32. The disk structure, buffers, variables etc. do all depend on 16-bit block
numberss and 512 byte blocks. Using logical block numbers would allow you to
keep the current disk structure to some degree but there's still the software
that has to support it. Looks like someone is gonna release ProDOS 3.0 :-)
> > I hope the Mac will once get rid of this logical block business. With 64-=
> bit
> > architecture, there's really no need for that.
>
> Wait and see. MacOS 8 should get rid of the logical block business, =
> which makes small files bigger than they really are. =
oops, I guess rather vice versa. It's only due to logical blocks that files are
bigger than they really are (not counting the minimal losses when rounding up
to the next 512 byte boundary).
With logical blocks, you are loosing 0 bytes to 2k or 17k or even more,
depending on the partition's size. Without logic blocks, you will never loose
more than physical block size - 1. It doesn't matter whether you have big or
small files...
- henrik
--
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