Re: Announcement: Colorix for Apple II

[Andy McFadden <fadden@fadden.com>]

In comp.sys.apple2 Ventzislav Tzvetkov <drhirudo@mail.bg> wrote:
> As usual the sourcecode is available on the disk. Currently the game
> is easily installable on hard disk, since it's a binary file starting
> at $2000. I had some problems because for some reason the --start-addr
> option in the CC65's linker didn't work here (I use CC65 2.9.2), so
> the game is still located at $0800, but since it's bigger than 6K, if
> I compress it at $2000 and then uncompress it to $0800, the code
> overlaps the uncompressing routine with unpredictable results. The
> solution is easy though. The Binary still loads at $2000, but it then
> relocates itself to $4000 and starts the uncompression from there
> (this will work for any other address $6000 for example), with the use
> of the MOVE subroutine from the monitor ($FE2C), and when the game
> overlaps the start code, it's not needed already. Refer to the
> sourcecode for more information on the used technics.

If you put the uncompress routine at the end and jump to it from the
start, you can uncompress directly at $800 and only overwrite data you
no longer need.

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