Re: Cloning BASIC.SYSTEM and porting INTBASIC to ProDOS

["Bryan Parkoff" <nospam@nospam.com>]

"Scott Alfter" <salfter@salfter.diespammersdie.dyndns.org> wrote in message 
news:43592088$0$28792$9a6e19ea@news.newshosting.com...
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> In article 
> <Pine.LNX.4.62.0510210300360.22573@static-141-149-129-16.buff.east.verizon.net>,
> Lyrical Nanoha  <LyricalNanoha@dosius.net> wrote:
>>1. I've seen PDOS.SYSTEM and AmperDOS, two BASIC.SYSTEM replacements that
>>use &-commands to do all their work.  I wonder if it would be very
>>difficult to hack PDOS.SYSTEM into being compatible with BASIC.SYSTEM,
>>just so as to have a version of BASIC.SYSTEM that isn't Apple-copyrighted.
>>I'm thinking about rewriting ProDOS itself too but that is of lower
>>priority (since I'm actually working on adding a ProDOS API emulation to
>>SDDapple, under the name VDOS).
>
> If you're doing this with the goal of adding capabilities not currently in
> ProDOS (such as increasing the maximum filesystem size beyond 32 MB), this
> could be interesting.  I'm not sure copyright is that big an issue, given
> that Apple has never seen fit to charge for it.
Scott,

    You can't increase the space capacity of ProDOS from 32MB to 2GB because 
it has the limitation of 16 bits.  Sixteen bits or WORD value hold block 
information such as track/sector information.  ProDOS first looks for sector 
table to find one byte then sector table has sub-sector table to look for 
more block information.
    I remember that Michael Mahon claims to say that there is a possibility 
to replace 16 bits to 32 bits so block information can hold in from sector 
to sector rather than sub-sector to sector, but it would be non-ProDOS or 
enhanced ProDOS.  The problem is that current version 2.0.3 and earlier 
version will not be compatible to new version of ProDOS (enhanced ProDOS). 
It means that it can't read files and directory from newer version of ProDOS 
which it supports 2GB.  A special utility is needed to accommodate the 
compatibility between current ProDOS and enhanced ProDOS.
    It is the same example of MS-DOS' FAT16 and FAT32.
    I have been considered to remodify ProDOS code for over years to support 
2GB, but I gave up.  I might change my mind in the future to go back to my 
enhanced ProDOS project.  I have already thought to support 64 partitions of 
32MB into single root directory which it goes up to 2GB space capacity.  It 
does not require to switch partition back and forth.

Bryan Parkoff