Re: cda?

[nathan@subzero.winternet.com (Nathan Mates)]

In article <4r6fdm$so3@news.ysu.edu>,
Adalbert Goertz <be404@yfn.ysu.edu> wrote:
>Is there a prodos8 program which would permit loading
>CDAs to memory without booting GSOS?

   [Tip: note that the above is the _correct_ way to quote someone.
Even if your editor doesn't directly support quoting, you can always
manually spend the extra few seconds inserting a > before the other
people's lines.]

   Roger Wagner had one that came out very early on in the life of the
GS, called P8CDA. [Which was _not_ included on my disk of SoftSwitch,
a separately published program.] Problem is, it only supports the very
initial revisions of ProDOS 16 & GS/OS OMF (Object Module Format), so
recent CDAs won't work.

   Next, many CDAs may refuse to run under ProDOS 8. Anything that
tries to access the disk is right out unless it's got a load of extra
code to explicitly support ProDOS 8 directly. [And even then it can't
deal with forked files or anything else that's fun.] Next, a lot of
DAs want a chunk of the first 64K of memory called Bank 0 to store
their stack, direct page, and other stuff. Under GS/OS, it's fairly
easy to grab a small section and use that, but ProDOS 8 reserves all
of that memory, so they can't do that. As a CDA, they get a minimal
area at 00/0100-00/01FF, but that's not enough for anything serious.

   Even linking CDAs with -x to avoid ExpressLoad still won't work for
a lot of stuff-- there's different header formats. I ran into this
when trying to get my GameHacker CDA to load on ProDOS 16 boot disks.
I eventually wrote a program to translate the header format backwards,
but that's a real hack and not intended for general use.

   Bottom line: ProDOS 8 and GS programs tend not to get along, and
you need some real hacks to get stuff working. You'll eventually have
to weigh your desire to use a very limited OS & environment versus the
extended power, functionality, and ease of programming that GS/OS
allows.

Nathan Mates
--
<*> Nathan Mates http://www.ugcs.caltech.edu/~nathan/      <*>
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