6502 CPU Emulator

MOS Technology 6502 8-bit microprocessor core to be uses as a go module.

All opcodes and memory modes implemented and tested in Klaus Dormann test suite.

Currently project using this core:

https://github.com/cassianoperin/6502_console

https://github.com/cassianoperin/Atari2600

Emulation Status

• Klaus Dormann 6502 Functional test suite
• 56 Instructions (opcodes)
• 13 Memory Addressing Modes
• One 8-bit accumulator register (A)
• Two 8-bit index registers (X and Y)
• Seven 1-bit processor status flag bits (P)
• Opcode cycles counter
• Address BUS
• Data BUS
• IRQs
• NMIs

Improvements

• Put opcodes debug message on start OR end of opcodes

Usage

Import 6502 CPU into the code

import CPU_6502 "github.com/cassianoperin/6502_GO_Core"

Use the functions provided

Initialize the CPU

CPU_6502.Initialize()

Initialize Timers

CPU_6502.InitializeTimers()

Read ROM to the memory

CPU_6502.ReadROM(<filename string>)

Reset Vector: 0xFFFC | 0xFFFD (Little Endian)

CPU_6502.Reset()

Interpreter

CPU_6502.CPU_Interpreter()

Documentation:

6502

http://www.6502.org/

https://web.archive.org/web/20150217073759/http://homepage.ntlworld.com/cyborgsystems

http://datasheets.chipdb.org/Synertek/6502.pdf

Architecture

http://www.obelisk.me.uk/6502/architecture.html

http://www.weihenstephan.org/~michaste/pagetable/6502/6502.jpg

https://www.bbc.co.uk/bitesize/guides/zr8kt39/revision/4

Opcodes:

https://www.masswerk.at/6502/6502_instruction_set.html

http://www.obelisk.me.uk/6502/reference.html

Addressing:

https://slark.me/c64-downloads/6502-addressing-modes.pdf

http://www.obelisk.me.uk/6502/addressing.html

http://www.emulator101.com/6502-addressing-modes.html

Stack:

https://wiki.nesdev.com/w/index.php/Stack

Interrupts:

http://www.cs.jhu.edu/~phi/csf/slides/lecture-6502-interrupt.pdf

Buses

http://www.plingboot.com/2015/10/homebrew-6502-part-2/

https://slideplayer.com/slide/3944506/