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/* Memory Access */
In order to make up for the lack of registers, the 6502 includes a zero page addressing mode ($0000-$00FF) that uses only 1 address byte in the instruction instead of the 2 that are needed to address the full 64 KB of memory. This provides fast access to the first 256 bytes of RAM by using shorter instructions.
The stack is permanently located in memory page 1 ($0100 to $01FF) and managed by the 8-bit stack pointer (S), with an initial value of $FF. It grows downward as data is pushed onto the stack.
Instructions PHA and PHP push the accumulator and processor status onto the stack, while PLA and PLP pull them back. Subroutine calls with JSR store the return address on the stack, and RTS retrieves it to continue execution. Similarly, interrupts (BRK) push the program counter and status, while RTI restores them. The stack has a 256-byte limit, and overflow occurs if not managed properly.
