Author Topic: Using Extra Ram Pages  (Read 4960 times)

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Offline ralphdspam

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Using Extra Ram Pages
« on: July 29, 2011, 03:42:53 am »
Hi.  I'm pretty sure that this question has already been asked, but I have not been able to find it (not even on wikiti).

Which extra ram pages am I able to use on an 84+ SE with missing pages? 

Thanks for the answer. :)
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Offline calc84maniac

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Re: Using Extra Ram Pages
« Reply #1 on: July 29, 2011, 05:56:10 am »
Hi.  I'm pretty sure that this question has already been asked, but I have not been able to find it (not even on wikiti).

Which extra ram pages am I able to use on an 84+ SE with missing pages? 

Thanks for the answer. :)
Well, on these calculators each of the pages from $82 to $87 refer to the same 16KB of RAM, so you can use whichever one you want. Typically you'd use page $82 or page $83, since those are the unofficial "scratch pages" on the calculators that do have the extra RAM. Just watch out for the MathPrint data which is on page $83 (and all of the other "pages" on new calculators)
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Offline ralphdspam

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Re: Using Extra Ram Pages
« Reply #2 on: July 29, 2011, 06:22:53 am »
Well, on these calculators each of the pages from $82 to $87 refer to the same 16KB of RAM, so you can use whichever one you want. Typically you'd use page $82 or page $83, since those are the unofficial "scratch pages" on the calculators that do have the extra RAM. Just watch out for the MathPrint data which is on page $83 (and all of the other "pages" on new calculators)
So I can only actually use page $82?  I'm sorry; I don't really understand.  I'm like half asleep right now. :P
« Last Edit: July 29, 2011, 06:24:07 am by ralphdspam »
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Offline thepenguin77

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Re: Using Extra Ram Pages
« Reply #3 on: July 29, 2011, 11:33:15 am »
You can use whatever page you want, you just have to realize that pages 82h-87h are actually the same page. If you output 82h, write something, then output 83h, the value you just wrote will still be there.

As for what page to use, I recommend 83h. The reason for this is that this is the page the OS uses to store it's data. Now, it might seem a little strange to use the same page that the OS uses, but there is a purpose. On calculators with the full ram, yes, you'd be putting yourself in danger by using page 83h, but on the other calcs, there is only one extra page, so no matter what you are writing to the dangerous page. This way, by using page 83h, you can test your program on calculators that have the full ram (wabbitemu) while still insuring compatibility with calculators with the limited ram.
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Offline ralphdspam

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Re: Using Extra Ram Pages
« Reply #4 on: July 29, 2011, 04:08:56 pm »
ok. Which areas of page $83 should I use or avoid?

Again, I must wonder why TI does this stuff!
« Last Edit: July 29, 2011, 04:10:03 pm by ralphdspam »
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Offline thepenguin77

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Re: Using Extra Ram Pages
« Reply #5 on: July 29, 2011, 06:31:55 pm »
http://wikiti.brandonw.net/index.php?title=83Plus:OS:OS_2.53MP_Changes&#Memory (I wrote that btw)


You'll notice that the command history fits very nicely into saveSScreen :D
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Offline ralphdspam

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Re: Using Extra Ram Pages
« Reply #6 on: July 30, 2011, 03:18:27 am »
http://wikiti.brandonw.net/index.php?title=83Plus:OS:OS_2.53MP_Changes&#Memory (I wrote that btw)
You'll notice that the command history fits very nicely into saveSScreen :D
Thanks.  You have been a big help.  You deserve a +1 for that.  :)
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Offline calcdude84se

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Re: Using Extra Ram Pages
« Reply #7 on: July 30, 2011, 03:57:37 pm »
"RAM page 3, 977Eh–9A7Dh -- previous entries. Destroying this causes crashes."
Is there a way to destroy it that doesn't involve crashes?
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Offline calc84maniac

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Re: Using Extra Ram Pages
« Reply #8 on: July 30, 2011, 03:58:45 pm »
"RAM page 3, 977Eh–9A7Dh -- previous entries. Destroying this causes crashes."
Is there a way to destroy it that doesn't involve crashes?
Back it up and restore it. Or, I guess there might be a way to reinitialize it as an empty list of previous entries, but that might not go over well with the users.
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Re: Using Extra Ram Pages
« Reply #9 on: July 30, 2011, 04:07:35 pm »
Ah, okay. So, if I back that up, all of page $83 is usable?
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Offline calc84maniac

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Re: Using Extra Ram Pages
« Reply #10 on: July 30, 2011, 04:13:40 pm »
Ah, okay. So, if I back that up, all of page $83 is usable?
Well, as long as you don't let the OS touch it, such as generating an app base page table or doing USB transfers (though the latter uses page $82, it's the same page on newer calcs)
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