Hey C64 enthusiasts and retro computing fans! – So your beloved Commodore 64 is showing its age? Maybe the SID chip has gone silent, the VIC-II is displaying funky colors, or that notorious PLA has finally given up the ghost? Don’t panic – and definitely don’t pay those crazy eBay prices for 40-year-old chips that might fail next week!
The amazing thing about the C64 community in 2025 is that brilliant folks have been busy creating modern replacements for virtually every major component in our favorite breadbox. We’re talking FPGA-based chips that not only match the original functionality but often add cool new features while being way more reliable than anything Commodore ever made.
Whether you’re trying to resurrect a dead C64, building one from scratch (yes, that’s totally possible now!), or just want to future-proof your setup, this guide has you covered. We’ll walk through everything from drop-in chip replacements that cost less than a pizza to complete FPGA systems that’ll make your jaw drop.
The best part? Most of these aren’t just “good enough” replacements – many are actually better than the originals. Lower noise, more features, and they won’t randomly die on you like those aging MOS chips love to do.
So grab a coffee, fire up your favorite SID tune (while you still can!), and let’s dive into the wonderful world of keeping our C64s alive and kicking for another 40 years…
This list will grow ….
Complete FPGA-Based C64 Replacements
Ultimate 64 by Gideon Zweijtzer
- Type: Complete C64 motherboard replacement using FPGA
- Price: €177+ (Elite version available)
- Features:
- FPGA implementation of entire C64 (no emulation)
- Supports original 1541 drives, cartridges, and peripherals
- Dual SID sockets for real chips + FPGA SID emulation
- WiFi, Ethernet, HDMI, S-Video output
- 48MHz turbo CPU mode
- REU support and other accelerators
- Built-in Ultimate-II+ functionality
- Link: ultimate64.com
- Context: Considered the most powerful and feature-complete C64 replacement, but significantly more expensive than other options.
MiSTer FPGA with C64 Core
- Type: Multi-system FPGA platform with C64 core
- Price: $200-400+ depending on configuration
- Features:
- Cycle-accurate C64 implementation
- Multiple system support (not just C64)
- IEC device support for real drives
- Integer scaling and modern video output
- Supports EasyFlash cartridge format
- Uses ~42% of DE10-Nano FPGA resources
- Links:
- Context: Best value for multi-system retro gaming, excellent C64 compatibility with recent improvements by Sorg.
MEGA65 C64 Core
- Type: C64 core for MEGA65 hardware
- Features:
- Based on MiSTer C64 core
- Hardware expansion port for real cartridges
- IEC port for real peripherals
- Near-perfect compatibility
- Link: C64.MEGA65.org
- Context: For MEGA65 owners wanting C64 compatibility.
Motherboard/PCB Replacements
SixtyClone by Bob’s Bits
- Type: Drop-in C64 motherboard replacement
- Price: ~$50-80 (PCB only)
- Features:
- High-quality reproduction PCB
- Requires original chips (6510, VIC-II, SID, CIA, PLA)
- Blue/gold or other color options
- Professional silkscreen for easy assembly
- Link: Tindie – Bob’s Bits
- Context: Perfect for restoration projects or building new C64s with original components.
Individual Chip Replacements
VIC-II Video Chip Replacements
VIC-II Kawari by Randy Rossi
- Type: FPGA-based VIC-II replacement
- Price: $30-80 depending on version
- Features:
- Replaces 6567/6569 VIC-II chips
- NTSC/PAL switchable in software
- Enhanced video modes (80-column, 640×200)
- Large version includes HDMI/VGA output
- Passes all 280 VICE VIC-II tests
- Clock generation (no need for working clock circuit)
- Versions: Mini (basic) and Large (with HDMI)
- Links:
- Context: Excellent replacement for failing VIC-II chips, adds modern features while maintaining compatibility.
SID Audio Chip Replacements
ARMSID/ARM2SID by Nobomi
- Type: ARM Cortex-M4 based SID replacement
- Price: ~$50-70
- Features:
- STM32F410 ARM Cortex M4 @ 100MHz
- Accurate 6581/8580 emulation with auto-detection
- Significantly lower noise than original
- Configuration utility for C64
- Firmware updates from C64
- Dual SID support (ARM2SID)
- Links:
- Context: Highly regarded for accuracy and low noise, popular choice among enthusiasts.
Kung Fu SID
- Type: GD32F405RGT6
- Price: 25 EUR
- Features: Heavily inspired by SwinSID and ArmSID, but no analog inputs yet!
- Github
FPGASID
- Type: FPGA-based SID replacement
- Price: €75+ per unit
- Features:
- Most accurate SID emulation available
- Dual SID emulation in single chip
- Audio input support
- Larger PCB with additional features
- Link: FPGASID Homepage
- Context: Flagship SID replacement, most expensive but highest accuracy.
BackSID by BackBit
- Type: Modern SID replacement
- Price: $29 USD
- Features:
- Auto-detects C64/C128 type
- Configuration software
- Firmware updates
- Mouse/paddle support
- Continuous firmware improvements
- Link: BackBit Store
- Context: Most affordable modern SID replacement, good value for money.
CIA Interface Chip Replacements
J-CIA64 by Jani Laatikainen (1nt3r.net)
- Type: FPGA-based CIA replacement
- Price: €39.95
- Features:
- Replaces MOS 6526/8521 CIA chips
- Passes all Wolfgang Lorenz test suite tests
- Works with all C64 revisions, C128, 1570/1571 drives
- Compatible with modern peripherals (WiFi modems, Ultimate-II+, etc.)
- 1MHz and 2MHz mode support
- Gold-plated pins
- Links:
- Context: First reliable FPGA CIA replacement, essential for building new C64s or replacing failed CIAs.
CPU Replacements
J-CPU by 1nt3r.net
- Type: FPGA-based 6510/8500 CPU replacement
- Status: Recently released (2024)
- Features:
- Complete 6510/8500 replacement
- Lower power consumption
- Better compatibility than 6502+adapter solutions
- Same footprint as original
- Link: 1nt3r.net
- Context: Newest addition to modern C64 replacements, addresses CPU failures.
MonoTech 6510/8501 Adapter
- Type: 6502 to 6510 adapter board
- Features:
- Uses modern 6502 CPU with adapter
- Adds missing 6510 functionality
- Link: MonoTech
- Context: Alternative approach using modern 6502 chips.
PLA Replacements
J-PLA
- Type: Modern PLA replacement
- Features:
- Direct replacement for failing C64 PLAs
- More reliable than original Commodore PLAs
- Link: Poly.Play
- Context: Addresses the notorious PLA failure issues in C64s.
PLAster by BackBit
- Type: Modern PLA replacement
- Features:
- Alternative PLA replacement option
- Good reliability record
- Link: BackBit Store
- Context: Part of BackBit’s modern replacement ecosystem.
PLA20V8 by Daniël Mantione
- Type: GAL-based PLA replacement
- Features:
- Uses modern GAL chips
- Well-tested replacement
- Context: Early successful PLA replacement project.
Additional Components
Clock Chip Replacements
- 8701 Clock Generator: Multiple modern replacements available
- Features: Essential for C64 operation, modern versions more reliable
RAM Replacements
- SRAM Modules: Modern SRAM replacements for original DRAM
- Features: More reliable than original chips, various suppliers
ROM Replacements
- Modern EPROMs: Flash-based ROM replacements
- Features: Easy to program, more reliable than original ROMs
Special Case Projects
C64x MiSTer Builds
- Type: MiSTer FPGA in C64x case
- Features:
- Authentic C64 appearance with modern internals
- Full keyboard functionality
- Multiple system support
- Context: Premium builds combining authentic aesthetics with modern technology.
HD-64 HDMI Upgrade
- Type: Internal HDMI output modification
- Features:
- Fits in RF modulator space
- Captures VIC-II signals via FPGA
- Pixel-perfect HDMI output
- Maintains original VIC-II functionality
- Context: Modern video output for original C64s without replacing the VIC-II chip.
Enhancements
- WIC64 – The Wireless interface for C64 – SX64 – C128 – VIC20
Where to Buy
Major Retailers
- Retro8bitshop: Largest selection of modern C64 components
- Video Game Perfection: European distributor for many products
- American Retro Shop: US-based retailer
- BackBit Store: Direct from manufacturer
- Ultimate64.com: Official Ultimate 64 sales
Specialized Vendors
- Bob’s Bits (Tindie): SixtyClone PCBs
- 1nt3r.net: J-CIA and J-CPU products
- RetroComp.cz: ARMSID and other components
- Protovision: Various replacement chips
- Poly.Play: PLA replacements and other components
Building a Complete Modern C64
Cost Estimate: $300-600 depending on choices
Essential Components:
- SixtyClone PCB (~$60)
- J-CIA64 x2 (~$80)
- J-CPU (~$50-70)
- VIC-II Kawari (~$50-80)
- ARMSID or BackSID (~$30-70)
- Modern PLA replacement (~$20-30)
- Various passive components and logic chips (~$50-100)
Result: A completely new C64 with modern, reliable components that will likely outlast original hardware while maintaining full compatibility.
Thoughts
The C64 homebrew community has made remarkable progress in creating modern replacements for virtually every major component. It’s now possible to build a C64 with 100% new parts using these replacements, addressing the reliability issues of 40-year-old components while often adding enhanced features. These replacements ensure the C64 platform remains viable for both enthusiasts and newcomers for decades to come.
