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6502-VCS

6502-VCS.png

An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.

📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family. See VCS's page in the family appendix.

Table of Contents

Overview

The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.

The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.

Architecture

All AC6502 computers share:

  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems

Systems

ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)

Software

ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload

Hardware

This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.

Main Board

Hardware/Main Board/

The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.

Revision History

Rev 1.1

  • Pull-up resistors changed from 1kΩ to 10kΩ.

Rev 1.0

  • Initial release.

Input Board

Hardware/Input Board/

Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.

The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.

Output Board

Hardware/Output Board/

Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.

ROM Cart

Hardware/ROM Cart/

Swappable ROM cartridge for the VCS system. Comes in two versions:

  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).

Firmware

This repository contains PlatformIO-based firmware for the Input Board.

IB Controller

Firmware/IB Controller/

Firmware for the ATmega1284p on the Input Board. Provides:

  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA

See Firmware/IB Controller/README.md for setup and usage instructions.

CAD

CAD/

3D-printable enclosure parts and laser-cut top panels for the VCS system.

Production

Production/

JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.

Schematics

Schematics/

PDF schematics for each board.

Libraries

Libraries/

Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.

Bill of Materials

Main Board

ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND

Input Board

ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND

Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.

Output Board

ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602

ROM Cart (Rev 1.0a)

ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N

ROM Cart (Rev 1.0b)

ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N

License

Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.
Firmware is released under the MIT License.

About

6502-VCS 8-Bit Retro Computer Project

Resources

Readme
CERN-OHL-P-2.0 license
Activity

Stars

3 stars

Watchers

0 watching

Forks

0 forks
Report repository

Contributors

Languages

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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
3 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
3 stars
Watchers
0 watching
Forks
0 forks
Report repository
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Languages

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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
3 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
3 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
3 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
3 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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6502-VCS
6502-VCS.png
An AC6502 retro-style 8-bit computer based on the 65C02 microprocessor.
📖 Guide:AC6502 Documentation — the user's and programmer's guide for the whole family.
See VCS's page in the family appendix.
Table of Contents
Overview
The AC6502 ecosystem is a family of open-source, 65C02-based computers sharing a common architecture, memory map, and BIOS. Each computer in the family is purpose-built for a different use case but runs the same software and firmware.
The VCS is a cartridge-based retro gaming console. It features a real 65C02 CPU, swappable ROM cartridges, VGA video output via Pico9918, SID audio via ARMSID, and support for PS/2 keyboards, matrix keyboards, and Atari 2600-compatible joysticks.
Architecture
All AC6502 computers share:
  • CPU: 65C02 (or accurate emulation)
  • Memory: 32KB RAM + 32KB ROM, with optional banked RAM expansion
  • Memory Map: Standardized across the ecosystem — zero page, stack, I/O space ($8000–$9FFF), system ROM, and interrupt vectors at $FFFA–$FFFF
  • Bus: 16-bit address bus, 8-bit bidirectional data bus, standard 65C02 control signals (RW, PHI2, RESET, IRQ, NMI, RDY, SYNC)
  • BIOS: A common BIOS provides the kernel, monitor, and BASIC interpreter across all systems
Systems
ProjectDescription
6502-ACEAll-in-one Computer Experience — A single board computer
6502-COBComputer On a Backplane — Modular desktop computer with expandable card slots
6502-DEVDevelopment Environment Vehicle — Emulation-based dev system
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console (YOU ARE HERE)
Software
ProjectDescription
6502-BIOSThe shared BIOS (kernel, monitor, BASIC) for all AC6502 computers
6502-EMULATOREmulator for the whole family — desktop app, browser build, and a command line for scripted runs
6502-PRGTemplate project for writing assembly language programs
6502-CRTTemplate project for writing assembly language cartridges
6502-ASMAssembly language example programs and demos
6502-BASBASIC program listings
6502-WOZMONWozmon as a standalone ROM
6502-NOPAn all-NOP ROM, for probing a board during bring-up
6502-DOCSThe documentation site — the guide, the printable reference cards, branding and label artwork
cffsBuilds CompactFlash disk images for the BIOS filesystem
bastokTokenizes BASIC listings into .prg images, and back
bin2wozConverts a binary into a Wozmon serial upload
Hardware
This repository contains KiCad 7.0+ PCB designs for the three boards that make up the VCS system.
Main Board
Hardware/Main Board/
The core board containing the 65C02 CPU, 32KB SRAM, 32KB EEPROM, clock, and reset circuitry. Runs at 1 MHz and provides the bus connection for the Input and Output boards.
Revision History
Rev 1.1
  • Pull-up resistors changed from 1kΩ to 10kΩ.
Rev 1.0
  • Initial release.
Input Board
Hardware/Input Board/
Unified input board supporting a matrix keyboard, PS/2 keyboard, and Atari 2600-compatible joysticks. Uses a 65C22 VIA and an ATmega1284p microcontroller as the keyboard encoder controller.
The joysticks share the VIA ports with the keyboard encoder rather than having connectors of their own: they come in on the J1 PORT B and J2 PORT A box headers, with JOY(1) reading PORT B and JOY(2) reading PORT A. See Joystick Interface for the wiring options and the bitmask the BIOS returns.
Output Board
Hardware/Output Board/
Combined VGA video output (via Raspberry Pi Pico running Pico9918) and SID audio output (via ARMSID). Provides TMS9918A-compatible graphics modes at 640×480 VGA and 3-voice SID synthesis.
ROM Cart
Hardware/ROM Cart/
Swappable ROM cartridge for the VCS system. Comes in two versions:
  • Rev 1.0a — Uses the 28C256 32KB EEPROM (electrically erasable, no UV eraser required).
  • Rev 1.0b — Uses the 27C256 32KB EPROM (UV-erasable).
Firmware
This repository contains PlatformIO-based firmware for the Input Board.
IB Controller
Firmware/IB Controller/
Firmware for the ATmega1284p on the Input Board. Provides:
  • Matrix keyboard scanning and encoding
  • PS/2 keyboard interface
  • Atari 2600-compatible joystick input
  • Parallel I/O to the AC6502 bus via 65C22 VIA
See Firmware/IB Controller/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the VCS system.
Production
Production/
JLCPCB-ready Gerber files and BOM/CPL for PCB fabrication and assembly.
Schematics
Schematics/
PDF schematics for each board.
Libraries
Libraries/
Shared KiCad symbol and footprint libraries used across all AC6502 hardware projects.
Bill of Materials
Main Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3–C1110100nFUnpolarized capacitorC49678
C2110uFPolarized capacitorC7171
D111N5819Schottky Diode SOD-323FC191023
D21LEDLED 0805C2297
J11PWR_SWJST XH 1×2455-2247-ND
J21ROM WEPin Header 1×2AMAZON
J31USB-CUSB 2.0 Type-C ReceptacleC2988369
J41RESET_SWJST XH 1×2455-2247-ND
J51HRDB ENPin Header 2×2AMAZON
J61CLOCK_ENBL_SWJST XH 1×2455-2247-ND
J716502 ENPin Header 1×2AMAZON
J81EXP ENPin Header 2×5AMAZON
J916502 Card ConnectorCard Edge 2×20A31723-ND571-5-5530843-4
J1016502 BusBus Connector 2×20AMAZON
Q11SS8050NPN Transistor SOT-23C2150
R1, R4, R931kResistorC17513
R10–R14510kResistorC2930231
R211MResistorC17514
R3147kResistorC17713
R5, R625.1kResistorC27834
R71330ResistorC17630
R8110kResistorC17414
SW11ResetPush ButtonC318884
U11LM555xMTimer SOIC-8C7593
U21AS6C62256SRAM DIP-281450-1033-ND913-AS6C62256-55PCN
U31AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U4, U5, U7374HC00Quad NAND SOIC-14C5586
U6165C02CPU DIP-40955-W65C02S6TPG-14
X11OCXO-14Crystal Oscillator DIP-14X937-ND
Input Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C1, C3, C5–C86100nFUnpolarized capacitorC49678
C2, C4222pFUnpolarized capacitorC107114
D111N914Schottky Diode1N914FS-ND
J11PORT BBox Header 2×62057-BHR-12-VUA-NDAMAZON
J21PORT ABox Header 2×62057-BHR-12-VUA-NDAMAZON
J31PS/2 KEYBOARD6-pin Mini-DIN806-KMDGX-6S-BSAMAZON
J416502 BusBus Connector 2×20AMAZON
J51KEYBOARDDB-25 Connector609-1505-ND
J61IO SELECTPin Header 2×8AMAZON
R111KResistorC17513
U1165C22VIA DIP-40955-W65C22N6TPG-14
U21ATmega1284-PMCU DIP-40ATMEGA1284-PU-ND556-ATMEGA1284-PU
U3174HC138Decoder SOIC-16C5602
Y1116 MHzCrystal HC49-U3155-16M20P2/49US-ND
Joysticks: there is no DB-9 in this BOM because the board does not carry one. The joysticks share the VIA ports with the keyboard encoder and connect through the J1 PORT B and J2 PORT A box headers, using a helper board from the 6502-COB project — the GPIO Helper for a direct box-header connection, or the Joystick Helper to convert a port to a DB-9 with pull-ups fitted. Budget for one helper per stick.
Output Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
C111uFCapacitorC28323
C2, C322.2nFCapacitorC28260
C5–C106100nFUnpolarized capacitorC49678
D111N914Schottky Diode1N914FS-ND
J11VDDJST XH 1×2455-2247-ND
J21AUDIORCA ConnectorPJRAN1X1U02X-ND
J61INT SelectPin Header 1×3AMAZON
J71IO SELECTPin Header 2×8AMAZON
J816502 BusBus Connector 2×20AMAZON
R111kResistorC17513
U11Pico9918AVideo Chip DIP-40LINK
U216581SID Chip DIP-28LINK
U3, U4274HC138Decoder SOIC-16C5602
ROM Cart (Rev 1.0a)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT28C256EEPROM DIP-28AT28C256-15PU-ND556-AT28C25615PU
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
ROM Cart (Rev 1.0b)
ReferenceQtyValueDescriptionDigiKeyMouserOther
C1, C22100nFCapacitor478-5732-NDAMAZON
U11AT27C256EPROM DIP-28AT27C256R-70PU-NDLINK
U2174HC138Decoder DIP-16296-1575-5-ND595-SN74HC138N
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License.
About
6502-VCS 8-Bit Retro Computer Project
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CERN-OHL-P-2.0 license
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