Harvard Architecture
The Microchip Pic microcontrollers are based on the Harvard Architecture. This means that the program and data memory are in separate address spaces i.e. the each have their own address and data bus. In addition to program and data memory the stack also has its own dedicated memory which will allow 31 levels or subroutines.
Reset
On reset the address counter will be set to 0x000000. However the instruction placed at this address is normally a jump. The jump is used because the interrupt vectors sits at 0x000008 and 0x000018.
Memory Modes
Transparent to a C programmer the Pic can have two memory modes small and large and some areas program memory can be protected to keep your design from others eyes.
File Register
The Pic has between 4K and 8K of data memory, known as the File Register. The data is organised into 256k banks that can be accessed using a bank select register. There are areas in Bank0 and Bank15 that can be accessed without the need of swapping banks. This is known as Access Ram and contains the Special Function Registers. Again this is transparent to the C programmer.
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