Accessing the backup RAM section

The backup RAM is at address 0x300000.

There is a way to create a section for the linker and then to tell the linker to place variables there, but it is easier to create a structure (TMyApplication) that contains all the data that needs to be backed up and then to put that structure at 0x300000. It also makes it a whole lot easier to check that the structure is less than 2KB (sizeof()). In the test menu of the HP-20B (ON-PMT), the number under the copyright message is just that; the size of TMyApplication. This is a good way to check and make sure that the size is less than 2KB.