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Atari coding BBS
| Re: PC addressing mode |
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Posted by: Mr. Styckx
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Apr,19.2013-14:27
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Hi,
first, I think it's 32kB, not 16kB.
If you use absolute address mode on .W 16 bit addresses, it will be expanded to a 32 bit address using bit 15 as bit 16-31.
This means you can't use address with bit 15=1, as it would be extended as $ffffxxxx (and would likeky point to some IO register).
You can use any address from 0 to 32767, assuming these addresses are free, which means you must stop all OS activity or start your program from the AUTO/ folder in such a way that you can expect a large part of the lowest 32k of ram to be free. There's no real rule to ensure you will have free ram in the lowest 32k.
Many demos do that for extra performance as they don't use the OS anymore. In your case, as you might need file access system calls, blindly overwriting all the lowest 32k could create crashed.
Nicolas
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Topic
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Posted by
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Date
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PC addressing mode
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Sallafranque/Thadoss
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Apr,15.2013-21:42
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Re: PC addressing mode
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ggn
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Apr,15.2013-22:35
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Re: PC addressing mode
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Sallafranque/Thadoss
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Apr,15.2013-22:46
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Re: PC addressing mode
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ggn
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Apr,15.2013-23:10
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Re: PC addressing mode
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Sallafranque/Thadoss
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Apr,15.2013-23:36
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Re: PC addressing mode
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Sallafranque/Thadoss
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Apr,15.2013-23:07
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Re: PC addressing mode
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mikro
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Apr,16.2013-02:47
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Re: PC addressing mode
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Defjam
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Apr,17.2013-17:43
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Re: PC addressing mode
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Sallafranque/Thadoss
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Apr,19.2013-00:21
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Re: PC addressing mode
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Mr. Styckx
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Apr,19.2013-14:27
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Re: PC addressing mode
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Defjam
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Apr,19.2013-18:35
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Re: PC addressing mode
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dml
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May,29.2013-00:25
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Re: PC addressing mode
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evil
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May,29.2013-14:54
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Re: PC addressing mode
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Cyprian
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Jun,01.2013-16:17
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Re: PC addressing mode
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evil
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Jun,01.2013-20:00
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What's the anti-troll code?
That's your personal code to be able to add comments and messages on the dhs.nu site.
Don't have a code or forgot it? Fix it here.
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