Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!apple!claris!jazzman
From: jazzman@claris.com (Sydney R. Polk)
Newsgroups: comp.sys.apple
Subject: Re: resource and data forks
Message-ID: <10173@claris.com>
Date: 18 May 89 21:12:22 GMT
References: <8905161922.AA00955@crash.cts.com>
Organization: Claris Corporation, Santa Clara CA
Lines: 32

From article <8905161922.AA00955@crash.cts.com>, by stevef@pro-nucleus.UUCP ("Steven J. Freitas"):
> Network Comment: to #514 by pnet01!crash!apple.com!mattd
> 
> Well, something I'd like to know is whether P8 will be patched so that it
> could access more than 32 meg per volume? It seems that this aspect of upgrade
> has been forgotten in the midst of the recent developments.
> 
> UUCP: crash!pnet01!pro-sol!pro-nucleus!stevef
> ARPA: crash!pnet01!pro-sol!pro-nucleus!stevef@nosc.mil
> INET: stevef@pro-nucleus.cts.com          ProLine: stevef@pro-nucleus
> ALPE: SteveAdept
It is impossible with ProDOS to acces more than 32 meg of space on a 
volume because addressed in ProDOS can only address that much.  Period.

GSOS doesn't have this limitation because it has more bits allocated
for disk blocks internally.

32 Meg in 512 K blocks requires 7 bits, which means that the block
address can be stored in one byte.  The other bit is used for something
like marking a block as used or some nonesuch.  ProDOS 8 uses only one
byte for addresses, so it cannot access more than 32 meg.  This is so
ingrained into the OS that a patch is basically impossible.

GS/OS uses more than one byte for block addresses, so doesn't have the 32
Meg limitation.


-- 
Syd Polk           | Wherever you go, there you are.
jazzman@claris.com | Let the music be your light.
GO 'STROS!         | These opinions are mine.  Any resemblence to other
GO RICE!           |  opinions, real or fictitious, is purely coincidence.