Re: GS/OS: looking for info on VCB and FCB

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

Toinet <antoine.vignau@laposte.net> wrote:

> On 21 sep, 10:51, David Wilson <mcs6...@gmail.com> wrote:
> > I just had a look at "Apple IIgs GS/OS Reference" manual and the index
> > does not even mention either of those terms...
> >
> > I next had a look at "Apple IIgs GS/OS Device Driver Reference" manual
> > and again found no mention of those terms.
> >
> > If GS/OS does use similar structures, it must use completely different
> > names.
> 
> Thanks David,
> I have the two books you have had a look at and they do not mention
> the existence of VCR and FCR. They do not mention the following system
> service calls:
> - $01FC00 - DEV_DISPATCHER
> - $01FC24 - ALLOC_VCR
> - $01FC28 - RELEASE_VCR
> - $01FC2C - ALLOC_FCR
> - $01FC30 - RELEASE_FCR
> - $01FC3C - GET_SYS_GBUF
> - $01FC40 - SYS_EXIT
> - $01FC48 - FIND_VCR
> - $01FC64 - GET_FCR

[snip]

I've read all of the GS/OS documentation and don't recall any of that.

It sounds like you are looking at part of the internal layer of GS/OS
which Apple never publically documented. GS/OS uses "File System
Translators" (FSTs) to implement specific file systems, and I expect
these are part of that layer.

The FST mechanism was never documented by Apple, and as far as I know,
nobody other than Apple ever released a GS/OS FST.

The device driver layer was well documented, and it is possible to write
third party drivers. They deal with volumes at the block level.

The main reason that Apple never documented FSTs is that every time the
released a new major version of GS/OS or added a new FST, they needed to
make changes to the programming interface between GS/OS itself and the
FSTs, to add new features or change existing ones.

Given that System 6.0.1 (with GS/OS 4.0.3, IIRC) is the last IIgs System
version, if anyone does manage to come up with documentation for its FST
layer, it might be feasible to write a third party one, as long as it
doesn't require any capabilities beyond what the current FSTs can do.

Which GS/OS version or IIgs System version were you looking at to derive
the above information?

-- 
David Empson
dempson@actrix.gen.nz