Re: The Difference between ProDos - 16 and GS/OS.

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <21JAN199518190503@cc.weber.edu>,
Michael Keeney <mkeeney@cc.weber.edu> wrote:
>
> At the time I purchased my IIe, ProDos was just coming on the scene.  This
> was in 1984.  And when the IIgs came out I understood that Prodos 16 was
> the operating system for that particular Apple II.  Now, I'm hearing
> a lot about GS/OS.  Can anyone out there explain to me the difference
> between ProDos 16 and GS/OS?

No problem.

ProDOS-16 is the original operating system for the IIgs, released at
the same time as the IIgs, in late 1986.  IIgs System 1.0 through 3.2
includes ProDOS-16.

ProDOS-16 was really just an "interim" operating system, enough to
enable the IIgs to operate in native mode (e.g. accessing the full
address space) without adding much functionality.

Internally, ProDOS-16 is actually running a modified copy of ProDOS-8,
with a "front end" that translates the calls and copies data around as
required.  This makes ProDOS-16 rather slow.


GS/OS was released in 1988, with System 4.0.  GS/OS is a new operating
system, completely running in native mode (except when it calls older
device drivers).  Loaded device drivers and multiple file systems are
supported, as well as resource forks and several other features.

Disk I/O is much faster with GS/OS, because extra levels of buffering
are eliminated, and native mode drivers allow more flexible operation.
GS/OS also provides a simple cacheing mechanism, mainly used to cache
directory structures.

GS/OS is compatible with ProDOS-16, to the extent that it emulates the
ProDOS-16 operating system calls.  It also provides a new set of
application calls which provide much more flexibility.


Some older applications may not work with GS/OS, but this is usually
because they bypass official entry points, or rely on undocumented
features of ProDOS-16 or earlier versions of the toolbox.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand