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6502-DEV

6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.

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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console

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 two boards that make up the DEV system.

DEV Board

Hardware/DEV Board/

The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.

DEV Output Board

Hardware/DEV Output Board/

The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.

Firmware

This repository contains PlatformIO-based firmware for both boards.

DB Emulator

Firmware/DB Emulator/

Firmware for the Teensy 4.1 on the DEV Board. Provides:

  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed

See Firmware/DB Emulator/README.md for setup and usage instructions.

DOB Display

Firmware/DOB Display/

Firmware for the Teensy 4.0 on the DEV Output Board. Provides:

  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)

See Firmware/DOB Display/README.md for setup and usage instructions.

CAD

CAD/

3D-printable enclosure parts and laser-cut top panels for the DEV 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

DEV Board

ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC

DEV Output Board

ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON

License

Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.
Firmware is released under the MIT License — DB Emulator, DOB Display.

About

6502-DEV 8-Bit Retro Computer Project

Resources

Readme
CERN-OHL-P-2.0 license
Activity

Stars

2 stars

Watchers

0 watching

Forks

0 forks
Report repository

Contributors

Languages

, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
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Skip to content
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6502-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
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})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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6502-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
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} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
Repository files navigation
6502-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
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})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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6502-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 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('^' + ".*" + '

Skip to content
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6502-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 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-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 stars
Watchers
0 watching
Forks
0 forks
Report repository
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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-DEV
6502-DEV.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 DEV'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 DEV is an emulation-based development system. It replaces the physical 65C02 CPU with a Teensy 4.1 running cycle-accurate 65C02 emulation via vrEmu6502.
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 (YOU ARE HERE)
6502-KIMKeypad Input Monitor - KIM-1 inspired minimal computer
6502-VCSVideo Computer System — Cartridge-based retro gaming console
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 two boards that make up the DEV system.
DEV Board
Hardware/DEV Board/
The main board hosting the Teensy 4.1. Provides 65C02 bus emulation, SD card storage, Ethernet, USB keyboard/joystick input, and hardware control buttons (Run/Stop, Step, Reset, Frequency). Includes a bus connector and card slot with level shifters for optional real hardware expansion.
DEV Output Board
Hardware/DEV Output Board/
The AV output board hosting a Teensy 4.0 and a 2.4" ILI9341 TFT LCD. Emulates a TMS9918A Video Display Processor and a MOS 6581 SID audio synthesizer, driven in real time via high-speed serial from the DEV Board. The DEV Board sends the same AV packets over USB at the same time, so a browser can render the output in parallel with this board — the two paths are simultaneous, not alternatives.
Firmware
This repository contains PlatformIO-based firmware for both boards.
DB Emulator
Firmware/DB Emulator/
Firmware for the Teensy 4.1 on the DEV Board. Provides:
  • Cycle-accurate 65C02 emulation
  • SD card ROM/cartridge/program loading and memory snapshots
  • Ethernet with mDNS (6502.local) and an embedded web control interface
  • USB keyboard and joystick support (Xbox 360/One)
  • AV packet output to both destinations at once — over USB to the browser (Web Serial API) and over hardware UART at 6 Mbps to the DOB Display
  • Serial terminal interface (115200 baud)
  • Hardware button control (Run/Stop, Step, Reset, Frequency)
  • Variable CPU clock speed
See Firmware/DB Emulator/README.md for setup and usage instructions.
DOB Display
Firmware/DOB Display/
Firmware for the Teensy 4.0 on the DEV Output Board. Provides:
  • TMS9918A VDP emulation (all four display modes, 256×192 active area)
  • MOS 6581 SID audio emulation (3 voices, ADSR envelopes, PWM audio output)
  • AV packet stream input at 6 Mbps over hardware UART from the DB Emulator (which also streams the same packets over USB to the browser)
See Firmware/DOB Display/README.md for setup and usage instructions.
CAD
CAD/
3D-printable enclosure parts and laser-cut top panels for the DEV 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
DEV Board
ReferenceQtyValueDescriptionLCSCDigiKeyMouserOther
BT11CR2032Battery HolderBAT-HLD-001-THM-ND712-BAT-HLD-001-THM
C1–C88100nFSMD CapacitorC49678
J11VBATPin Header 1×2 2.54mmAMAZON
J21SPIPin Header 2×4 2.54mmAMAZON
J31PANELPin Header 2×4 2.54mmAMAZON
J416502 Card ConnectorCard Edge 2×20 2.54mmA31723-ND571-5-5530843-4
J516502 BusPin Socket 2×20 2.54mmAMAZON
J61USB HostUSB Type-C ReceptacleC2988369
J71USB HOSTPin Header 1×5 2.54mmAMAZON
J81RJ45 w/ LEDsRJ45 8P8C Shielded1278-1052-ND
J91ETHERNETPin Header 2×3 2.00mmAMAZON
R1–R881kΩSMD ResistorC17513
R9, R10256kΩSMD ResistorC169923
R111150ΩSMD ResistorC17471
SW11Run/StopTact Push ButtonC318884
SW21StepTact Push ButtonC318884
SW31ClockTact Push ButtonC318884
SW41ResetTact Push ButtonC318884
U1–U3, U5, U65SN74LVC4245APWROctal Bus TransceiverC7859
U41Teensy 4.1MicrocontrollerPJRC
DEV Output Board
ReferenceQtyValueDescriptionDigiKeyMouserOther
C113.3nFDisc CapacitorAMAZON
J11AUDIOJST XH 1×2 2.50mm455-2247-ND
J21SERIALPin Header 1×4 2.54mmAMAZON
R611kΩAxial ResistorRNF18FTD1K00CT-NDAMAZON
U11Waveshare LCD HeaderPin Header 1×8 2.54mmAMAZON
U21Teensy 4.0MicrocontrollerPJRC
U31Waveshare 2.4in LCD2.4" ILI9341 TFT LCDAMAZON
License
Hardware designs are released under the CERN Open Hardware Licence Version 2 – Permissive.

Firmware is released under the MIT License — DB Emulator, DOB Display.
About
6502-DEV 8-Bit Retro Computer Project
Resources
Readme
CERN-OHL-P-2.0 license
Activity
Stars
2 stars
Watchers
0 watching
Forks
0 forks
Report repository
Contributors
Languages