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Author Topic: RAM clear on extra RAM pages?  (Read 2676 times)

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Offline Hot_Dog

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RAM clear on extra RAM pages?
« on: July 16, 2011, 11:07:45 am »
If a 15Mhz calculator crashes, does RAM on page $83 get cleared, even if the page resides in the $C000-$FFFF area?
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Offline thepenguin77

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Re: RAM clear on extra RAM pages?
« Reply #1 on: July 16, 2011, 01:00:45 pm »
What? Are you saying do 3>port ($05) then jump to $C000 essentially?

The answer is no, on hard resets, page 0 gets swapped into that bank. And before the OS/Boot code clears it, I believe they also swap page 0 in. So unless you pull out the little battery, page $83 will remain intact.
« Last Edit: July 16, 2011, 01:01:18 pm by thepenguin77 »
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Offline Hot_Dog

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Re: RAM clear on extra RAM pages?
« Reply #2 on: July 16, 2011, 03:45:16 pm »
Quote from: thepenguin77 on July 16, 2011, 01:00:45 pm
What? Are you saying do 3>port ($05) then jump to $C000 essentially?

The answer is no, on hard resets, page 0 gets swapped into that bank. And before the OS/Boot code clears it, I believe they also swap page 0 in. So unless you pull out the little battery, page $83 will remain intact.

It was a hypothetical situation.  What I want to do is save about 3 bytes of data to page $83 so it remains intact in case there's a crash
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Offline thepenguin77

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Re: RAM clear on extra RAM pages?
« Reply #3 on: July 16, 2011, 03:45:52 pm »
That will stick as long as something else doesn't kill it.
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