83Plus:OS:Ram Pages

This is to mark what ram pages may be used for short term or long term use.

It should be noted that on the newer calculator models (port 15 >= 55h) pages 82-87 refer to the same physical memory

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81

82

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OS 2.x uses at least some of the range 4000h through 4080h to store app base pages prior to app execution. This is always regenerated and the OS doesn't seem to have any issue when you modify it.
4100h through 433Ah is used for various buffers during USB communication.
On OSes with MathPrint, 577Eh through 5A7Dh is used to store the previous entries (command history). When this is modified, the calculator will crash if you scroll up on the homescreen past the program that modified it. Write 00 to 8E29 (numLastEntries) to prevent the user from scrolling up and to avoid the crash. This does not cause a memory leak and has no effect on older OSes (except with the OmniCalc entries menu). Zeroing this out doesn't seem to be necessary. Beware that on 48 KiB models, any page in the 82-87 range maps to this page.
On OSes with MathPrint, 5A7Eh through 5D7Dh is the homescreen graph buffer. Modifying this has caused flickering for some. You'll probably want to zero this if you use it.
3rd Party Uses
- Temporary swap for Virtual Calc by Michael Vincent
- Temporary code execution for Real Sound by James Montelongo
- Temporary CALCnet buffers for direct USB for Doors CS 7.2 and higher by Christopher "Kerm Martian" Mitchell

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