The memory is split into three distinct sections, as can be seen in the memory map :

• Read/write memory (RAM)
  Because we don't want the hassles associated with refreshing dynamic parts, I have chosen to go for a 2K static RAM. This provides us with 2048 bytes of memory.
  The first 768 bytes are claimed by Page Zero, the processor stack, and the serial buffering.
  The next 256 bytes is reserved for the application code.
  The remaining 1024 bytes is, currently, unallocated. It can be used by the application if larger data storage requirements are necessary.
   
  
• I/O
  The Input/Output devices are memory-mapped, so reading and writing bytes in the memory map will read and write registers in the hardware devices; the 6522 VIA and the 6551 ACIA.
   
  
• Read-only memory (ROM)
  For our purposes, we shall be comitting the application code and the BIOS into a single 4K EPROM. Within Amélie, the application and the BIOS are logically considered separate, and should be thought of as two distinct blocks (within two 2K EPROMs). Practically, this is nonsense, it is so much easier to include the two parts within the one EPROM. Smaller component count, less address decoding...

For information on the address decoding logic, please refer to the memory map document.