The 6502 family microprocessors belong to the category of 8-bit CPU. It only has a few internal registers that allow addressing 64Kb of memory. The processor is "Little Endian" which requires addresses to be represented in the format of "least significant byte first".

 

The 6502 family microprocessors regard the first 256 bytes of memory ($0000-$00FF) as "Zero Page"."Zero Page" is usually a place for storing data for "shorter instructions" (which means special addressing method) or allow indirect access to the memory. The second "256 bytes" of memory ($0100-$01FF) is reserved for the stack and system variables.  

 

The very last 6 bytes of memory $FFFA to $FFFF store the addresses of the

The 6502 family microprocessors usually have six registers:

1. one 8-bit accumulator register (A)
2. two 8-bit index registers (X and Y)
3. an 8-bit processor status register (SR)
4. an 8-bit stack pointer (SP)
5. and a 16-bit program counter (PC)