[Coco] converted AGD games - BIGPacks v2.4 released

[Pere Serrat]

Hi Art,
yes that's right!

I could add that the AGD files don't exist while developping the games.
Programmers use the AGD application to write the events and draw the
graphic parts. Then everything is put together when they compile the
executable/loadable file say .tap or .sna
The converter that creates the AGD file from the snapshot existed 
previously
for Spectrum machines and maybe other platforms, so we are re-using it.

If I am not wrong, the C compiler existed too to get a Z80 source code file.
What we had to do here was to change every command to make it create the 
best
possible 6809 code sequence. Mostly are function calls (to the engine)
so the only work is to set the needed parameters and call the correct 
function.
Only the port of the Z80 engine to 6809 code had to be done from scratch.

The biggest hurdle is that there are a lot of different AGD versions 
(1.0 to 4.8)
and the memory map differ from one another making it impossible to convert
some games unless you create a dedicated release of the converter for each
version. We took this approach ...

cheers
pere

Ps The AGD project is in permanent development, every now and then they add
new commands or features that allow for more complex game control
We have added as many of these as we have discovered!


----------------------------------------------------------------------
> Message: 1
> Date: Tue, 23 Jul 2019 01:56:16 -0400
> From: Arthur Flexser <flexser at fiu.edu>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Subject: Re: [Coco] converted AGD games - BIGPacks v2.4 released
> Message-ID:
> 	<CA+LuDccnEcMLJkg1TMRX05EMqBi2sufMDypqrMyAx_UUdRVgLA at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> So, let me see if I have this straight, now.  I was previously under the
> impression that all these converted games were games where you had access
> to the original AGD script files used to generate the Spectrum version of
> the game.  As I now understand it, what you had access to was the
> already-compiled game for the Spectrum, and you wrote a C program to work
> backwards from that to regenerate a version of the original AGD script file
> that wasn't available.  This, I gather, was possible because AGD stores
> things like tiles and sprites, etc. in some consistent format somewhere in
> the Spectrum's memory map that allowed a memory snapshot to be analyzed to
> figure out what the original AGD script looked like.  Then from there,
> conversion for the CoCo or Dragon was possible using a 6809-modified
> version of the original C-language Spectrum AGD compiler that you also
> wrote.
>
> Have I got that right?
>
> Nice going!
>
> Art
>
> On Sun, Jul 21, 2019 at 5:31 AM Pere Serrat <psergm at gmail.com> wrote:
>