Ultimate (Useful) Commodore 64 Upgrades and Mods List

This is my attempt to document and catalog all the (proven) mods and upgrades makers have developed for our beloved system over the years. Some will still be available, others might be relegated to eBay or whoever might revive them via reverse-engineering or building from sources. I’m not trying to be completely comprehensive here, as there are a great many “died on the branch” projects that were never completed, are focused solely on niche use cases, or simply never got enough support or traction to develop into a fully user-ready component. Case-in-point: There are SID projects out there intended for use in home-built SID jukeboxes, not necessarily in an actual C64. Those aren’t presented here because my intent is to provide options that will still let you use your Commie in its full, original form.

Rather than flirt with information overload, I’m only looking to build a curated list of options for folks who are trying to repair their system or are looking for new directions to help it grow.




If you still have the original design power supply that came with the C64 back in the day, you know, the one that weighs a ton and is pretty much a solid block of epoxy? Chuck it. Out the window, off a cliff, into that creepy uncle’s 50th birthday cake, I don’t care; get rid of it right-flippin’-now! They are known to wear down and burn out chips and mainboards with abandon. Modern, reliable replacements can be had for quite cheap, and bonus: they don’t weigh as much as a waterlogged armadillo!




A great way to replace the case on a budget, these are used cases for both breadbin and 64c, cleaned, refurbished and custom-painted as you like.

Individual Computers


Individual Computers is the current holder of the ORIGINAL C64c case molds, and they’re producing cases in a variety of color schemes, from the original 64c eggshell, to the 64 breadbin beige, and including SX64 black/blue and transparent!

They cost a little more and there’s some waiting involved, but these are factory-new cases with custom options that you never could have had without taking a risk with an old-fashioned rattle can on your own (or of course paying for a refurb job from Ami64!


Note: You do not need any of these if you have a 1541 Ultimate II; it does kernal swapping natively already! There are other 3rd-party devices out there that will also do kernal-swapping via cartridge port.

8-in-1 Kernal ROM Replacement


So this one comes pre-programmed with alternate kernals, and you switch the “active” one with the little teeny rotary dial before booting up. This does require opening up the system and potentially de-soldering the existing kernal ROM chip so you can socket this one in. It also has a rotary switch with more positions than there are storage slots on the chip, so I’m not sure what’s up with that. Good cheap option if you don’t change kernals often, cannot be modified unless you have the programmer and adapter to hook it up (so no JiffyDOS). Anyway, the ROMS that come pre-loaded are:

0 – Original Kernal [901227-03]
1 – 64er v1
2 – DeadTest (781220)
3 – DolphinDos 2.0
4 – MemoStar
5 – SD2IEC22 2.2
6 – SX-64 2.0 Original Kernal
7 – TurboDos 3.0

Open C64 Kernal Cart


Cheap, DIY and more accessible version of the 8-in-1 above. Works as a cartridge and uses jumpers to set the intended kernal to load.

8-in-1 Kernal Cartridge


Once again, pretty much the same as above, but this one is actually built and loaded already, and uses switches instead of jumpers. Same limits apply in that you can load your own kernal images onto it, if you have the necessary EEPROM programmer.

Easy Flash III


An excellent way to try out different kernals (to start), or create your own instant-launching program cartridge. Supports 8 kernal images and 7 game cart ROMs. This device can be re-programmed “live” on the C64 without a dedicated EEPROM programmer device. Basically supplants all the devices above for a slightly higher cost.



[ DIY ] : PLA20V8


[ BUY ] : PLA20V8


PLAster™ V2 (PLA replacement for C64 U17)


J-PLA C64 – PLA Replacement


PLAnkton by Eslapion



SlimPLA the compact Commodore 64 PLA Replacement PLA20V8 82S100



SRAM replacement (mod)


OEM restoration option



MOS CPU Replacer (DIY or assembled)


[ MOD ] : MCL64 “SuperCPU” Accelerator






Video (VIC-II)

(See VIC-II Kawari in Video tab. That is the only currently-viable full chip replacement, but provides a lot of extra features as well)


(replace the VIC-II chip entirely, provides a lot more tuning and modification options)



A little expensive by comparison, but have you seen the going prices for intact VIC-II chips on the market today? And that’s still taking a risk on whether the chips are even functional in the first place!

[ HDMI ]: VIC-II-Dizer / RGBtoHDMI
(best output quality overall)

[ Part 1 ]: https://www.tindie.com/products/c0pperdragon/vic-ii-dizer/

[ Part 2 (required if you want color and HDMI) ]: https://retrohackshack.com/product/rgbtohdmi/

This is a neat mod. The intercept board (shown here) sits in the VIC-II socket and the VIC chip mounts to it. The signal is stripped back to monochrome (luma levels only) and is handed off to the RGBtoHDMI unit, which, with the help of a Raspberry Pi Zero, references the grayscale levels of the incoming signal and re-applies the appropriate colors from a pre-set palette, giving crystal clear HDMI output in the process.

[ RF ]: Lumafix
(clean up the stock output signal, won’t help the older 6567R5 model VIC-II very much)



This mod also sits between the VIC-II chip and the motherboard, but it allows you to fine-tune the chroma signal components on the way out, helping to reduce the presence of jailbars and other interference artifacts. LumaFix64 is intended to give users a means to fine-tune the rather ham-handed muxing process Commodore utilized for video output.

[ COMPONENT ]: C0pperdragon’s Component Video Mod


This mod uses an FPGA to bypass the luma/chroma muxing function of the old RF can assembly inside the C64, re-interpret the intended output and generate a proper component (YPbPr) signal.




[ Best option as direct stock replacement]: A direct drop-in (literal plug-n-play) SID replacement, works for MOS 6581 and 8580. Supports the unique functionality some programs rely on, like 1351 mouse, paddle controllers and random number generation (because the original SID could generate white noise, a great source for random numbers!)



[ Like SID Deluxe. A major upgrade to the original! ]: This will work as a SID replacement and so much more! Not only does it feature improved standard audio, it can also convert the audio stream to (simulated) stereo, emulate a second SID for six voices (or true stereo!), support all the unique special functionality mentioned above, and can even run a keyboard light show! Not a bad way to invest 80 Euros (86 USD) at all!



[ Comparable to FPGASID ]: Must be the Ultimate variant, if you’re interested. Prior versions had some compatibility and teething issues. This one had a difficult time growing up, but it had some very patient and devoted devs to raise it up, and now it’s an upstanding contributing member of C64 enthusiast society. Sounds (heh) like a steal at 39 Euros!



[ Another drop-in replacement, but with some tweakability ]: This one is even cheaper at 32 USD, reproduces nearly all of the original’s features (minus the rarely-used audio passthrough capability) and offers settings tweaks to refine the sound to your liking.


C64/C128 WiFi Modem


Uses the ubiquitous and open source Zimodem firmware, a dead simple userport expansion that lets your Commie connect to your wifi network, and “dial” out to BBSes that live on through telnet!


[ MODEM ]: https://www.tindie.com/products/topsider/strikelink-wifi-modem-c64-designed-by-alwyz/
[ CASE ]: https://corei64.com/shop/index.php?route=product/product&product_id=108
[ MODEM w/ CASE ]: https://retrolemon.co.uk/commodore-upgrades/152-commodore-strikelink-wifi-modem.html

A variant of the WiFi modem, but a little simpler in that it wasn’t designed with an enclosure. You can buy one prefab in all its naked glory, or get one with a 3D printed case. Proven-working firmware has been updated by Alwyz and is available right here on this site. If you’re concerned about deviations from “stock” you can still get the original distribution of the firmware from http://www.mediafire.com/file/tm71a1oa1a3macc/alwyz_modded_firmware.rar

OR, you could build one of your own with a 3D printed case from my walkthrough, or buy one completed and ready to go (wink, wink)!


(Budget option, will get you going without the hassles of finding a real drive and maintaining floppies)


Paired with a Raspberry Pi 3(A or B), this creates a cycle-accurate emulated 1541 floppy drive, complete with IEC connections! Some programs actually rely on the quirks and flaws of the 1541 hardware to load, which makes them unusable with other solutions like SD2IEC. This way you can still drop your collection on a microSD card and have it accessible via either onboard display and nav buttons, or with a HDMI monitor and USB keyboard!

You can often find assembled hats and even complete units with the RPi on eBay, or build one yourself.

You can also use a PiZero, but that requires overclocking and I consider it generally not worth saving the few bucks. Pi4 is incompatible, as it can’t handle the low-level precise timings necessary to emulate this hardware.

See my write-up on this little bundle of magic right here.

1541 Ultimate-II
(Go for this if you have the funds, so many additional features to keep you busy!)

https://ultimate64.com/Main_products (supplies are a bit strained since COVID and the subsequent hike in FPGA prices. They’re working on a replacement)

A great deal more expensive, but really worth it. It actually offers the functionality of quite a few other independent mods in one chassis.

  • It still performs cycle-accurate emulation of a 1541, but can switch to other drive models to accommodate other floppy image types (1571/1581) without swapping ROM files
  • Provides an onboard file management system as well (the Pi1541 requires an external monitor or a teeny OLED screen at the very least to navigate options)
  • Has multiple onboard LEDs to display different status states
  • Can emulate other cartridges like Action Replay, Retro Replay, The Final Cartridge III, Super Snapshot V5, KCS Power Cartridge, the Epyx fastloader and many more
  • Has onboard ethernet that can be used to term into the device and trigger things like virtual disk swaps without rebooting the computer, and can also be linked with the modem emulator
  • Yes, there’s a Swiftlink emulator that can let you use the cartridge as a modem over ethernet to “dial out” to BBSes
  • Use alternate ROMs for the drive emulator and/or the C64 itself (JiffyDOS here I come!)
  • Has an audio output port (headphone) for stereo SID output, local sample playback, or simply providing floppy/tape drive access sounds


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