Re: [cc65] Atari Memory Layout

Hi Oliver,

On 26.09.10 18:14, Oliver Schmidt wrote:
>
> Okay, so the approach to first select the DOS to be used and then
> adjust the start address for that DOS - presuming that the program is
> (only) intended to run on the chosen DOS.

Yes. Maybe if $2000 is sufficient, use it like Shawn suggested. If it works
with the most popular DOSes (I'd say DOS 2.5, SpartaDOS, and MyDOS) it should
be OK.
To be more user friendly and prevent mysterious crashes if the load address
is too low and the program therefore overwrites parts of DOS, one could implement
a preload routine which would be loaded before the real program gets loaded and
issues a message about the problem. The system would crash anyway, but the user
would know why. I was thinking about adding this to the Atari runtime lib, but
haven't done yet. It would increase exe file size and load time, but won't
decrease the memory available to the program. What do fellow Atarians think,
would this be useful?


>> I don't know why $FFFF was chosen in the cited config file. I chose $BC1F
>> since
>> it's the value for a 48k+ Atari. For Ataris with less than 48k the startup
>> code
>> adjusts stack and heap accordlingly.
>
> So $BC1F is a rather optimistic value and there's no scenario with a
> higher value - correct?

What do you mean with optimistic? It's only optimistic in the sense that
you need an Atari with 48k or more memory. 30 years ago this probably wasn't
that common (Atari 400 and 600xl: 16k, Atari 800: anything from 16k to 48k in
4k increments), but nowadays I think it can be required to have at least 48k :-)

In the 800xl and newer there is ROM at $C000. It could be disabled to have
more memory available, but this is not supported by the cc65 runtime.

regards,
chris
----------------------------------------------------------------------
To unsubscribe from the list send mail to majordomo@musoftware.de with
the string "unsubscribe cc65" in the body(!) of the mail.