6502

The 6502 processor is an 8-bit CPU that was used in many computers and consoles, including the NES and SNES.

Specifications

Component	C++
Memory	`struct`

The first 256B of memory is referred to as the ($0000-$00FF).

Memory range	Description
0x0000-0x00FF	Zero Page
0x0100-0x01FF	Stack

#	Register	Size	Description
PC	Program Counter	16 bit	pointer to the next instruction
SP	Stack pointer	8 bit	holds low 8 bits of the next free location on the stack
A	Accumulator	8 bit	used for all arithmetic operations (except for incrementation and decrementation)
X	X register	8 bit	available for holding counter or offset values for memory access. It also has the special function of copying or changing the value of SP.
Y	Y register	8 bits	available for holding counter or offset values for memory access.

All opcodes are 1 byte in size, and their operands are 0, 1, or 2 bytes

Opcode	Code	Description
`CMP`		(src)
LDA		Load from ZP to A
`STA`	$85	Store accumulator in memory (src)

LDA #$33 ; Load 69 into A