Memory pages on ti84+

[allemensen]

How many ram pages does the TI-84+ have? And how can they be swapped to either 8000-B999 or C000-FFFF?
I need this for a custom equation parser (not based on the actual result, but on what they evaluate)

Or does some other way exist to gain lots of memory, which will remain usable even while doing other stuff (GetKey, menus)?

Thanks in advance

[simplethinker]

Here's a list of RAM pages (though I'm not sure if there are more for the 84+). As for ports:

Port 04 determines the memory map mode. The default is Mode 0 (and to my knowledge you'll want to stay in Mode 0, but I don't have extensive knowledge on the subject).
Port 05 determines which RAM page is mapped to C000h-FFFFh.
Port 06 determines which RAM/flash page is mapped to 4000h-7FFFh.
Port 07 determines the RAM/flash page mapped to 8000h-BFFFh.

[allemensen]

It worked! After some testing in the emulator I deemed it ready and it ran without a hitch on my calculator.

[FloppusMaximus]

If you're changing the values in ports 5 or 7, be careful. First of all, remember that your stack is usually in the C000-FFFF range, so after remapping that range, you won't be able to 'pop' or 'ret'. (You can alleviate this problem using port 27.)

Secondly, keep in mind that almost every part of the OS expects pages 80 and 81 to be mapped. This includes the system interrupt service routine, so you must always disable interrupts before changing the mapping. You can't perform application B_CALLs or B_JUMPs, and you can only use the very simplest of system B_CALLs.

[allemensen]

Don't worry, I know. I only remap $8000-$B999. I copy stuff to it using the stack, 16 bytes at a time, which works (I did a byte-by-byte compare afterwards)

[Igrek]

Hmmm, I didn't even know about ports 27 and 28. Might come in handy though, as I'm making a program that allows to store vars in the extra ram pages. (I might actually release an early beta this weekend)

[calc84maniac]