Commodore SX-64 upgrades

Adds wired 10 Mbit Ethernet and RR-Net-compatible networking to C64-family computers, with an optional multi-ROM socket.

For this system (exact model): The maker explicitly lists the SX-64 among the required-host options. Confirm physical cartridge clearance, Ethernet-cable routing, and software support for the intended network function.

The current RETRO Innovations store exposed the 64NIC+ category and a Choose Options purchase path on 2026-07-30. The product comes in four case and ROM-selector configurations. Network software, an Ethernet cable, and a 10 Mbit-capable network connection are required separately.

Uses one microSD cartridge and interchangeable adapters to load software and provide selected storage, cartridge, memory, and diagnostic functions on many vintage computers.

For this system (exact model): The current product page explicitly includes the SX-64 but requires the straight C64/128 adapter rather than the right-angle version.

The current store listed the assembled BackBit Pro for $129 on 2026-07-27 with one assembled adapter choice included. A microSD card is not included. Additional adapters are sold separately and require through-hole soldering. Firmware updates use the microSD card. An original C64 Assy 326298 needs the documented reset fix, and the SX-64 needs the straight C64/128 adapter.

Uses a PS/2 keyboard on supported Commodore computers or converts their original keyboards and optional joysticks for a PS/2-equipped host.

For this system (exact model): The SX-64 configuration uses the X5 connector and needs a DB25 male-to-male cable when a PS/2 keyboard drives the computer. Follow the documented SX-64 jumper settings; a board fitted with X5 will not also fit the C64 configuration.

The RETRO Innovations store exposed a configuration selector and Add to Cart path on 2026-07-30, with the bare PCB listed at USD 6 and configured kits priced separately. Kits and assembled units are made after ordering and normally take four to five weeks. The maker explicitly treats C=Key as a project rather than a fully supported product because its firmware is not extensively tested or easily upgraded; an AVR programmer is strongly recommended. Use a true PS/2 keyboard because passive USB adapters may not work.

Boots before the normal KERNAL to diagnose RAM and ROM faults on a Commodore 64 that cannot reach its startup screen.

For this system (exact model): Current seller documentation explicitly includes the SX-64. This is the 781220 RAM and ROM test, not a harness test of the SX-64's ports or built-in drive.

Retro Rewind listed its cartridge in stock at CAD 22 on 2026-07-30. TFW8b documented a compatible alternative for C64, C64C, SX-64, and C128 in 64 mode, but that listing was out of stock. Wait up to 60 seconds for a result. The original 781220 RAM routine covers only the lowest 4 KB, and the cartridge does not test the chips and I/O covered by a harness kit.

Adds the loopback modules needed for complete 586220 C64 or 785260 C128 port and interface diagnostics.

For this system (exact model): Use the open harness revision-2 or later SX-64 option and an SX-aware 586220++ image because the SX-64 lacks a cassette port. Keyboard testing needs the documented C128 keyboard dongle and gender changer; current complete sellers may omit that part. Confirm the selected kit's SX setting before power-up.

Current routes on 2026-07-30 included Retro-Updates' EUR 17.95 harness with an Add to Cart path, Retro Rewind's CAD 75 harness with a one- to two-week lead time, Retro Rewind's separate CAD 22 C128 keyboard dongle in stock, and AMI64's GBP 49 complete eight-ROM kit. Retro Electronics had one complete kit on 2026-07-25 but documented only one tested PAL C64 board revision. Confirm the exact harness revision, cartridge, keyboard dongle, cable lengths, model settings, and included manuals before ordering. Human review found no evidence that the current retail dongle solves the documented C128DCR keyboard-jack power conflict.

Packages 586220, 785260, and related service ROMs as current single-ROM and switchable multi-ROM diagnostic cartridges.

For this system (exact model): Retro Rewind's single-ROM 586220++ cartridge, its four-ROM cartridge, and ogHugo's two-sided cartridge explicitly support the SX-64. Use an SX-aware 586220+ build. ogHugo says the original SX-64 KERNAL must be active and replacements such as JiffyDOS disabled for a valid diagnostic result; full port testing still needs an SX-compatible harness configuration.

Current choices on 2026-07-30 included Retro Rewind's in-stock CAD 22 C64 586220++ and C128 785260 cartridges, its CAD 40 four-ROM C64 cartridge with a two- to three-day lead time, AMI64's GBP 19 eight-ROM C64 cartridge with an approximately seven-day lead time, ogHugo's USD 26.99 before-tax two-sided C64 cartridge with an Add to Cart path, Retro-Updates' EUR 17.99 two-sided C64 cartridge, and C64iSTANBUL's orderable two-ROM PCB with current fabrication files. DIY8BIT's USD 22.95 781220/586220 cartridge was unavailable while its Etsy shop was on break. Retro Rewind's older Dual Diag route now displays the store's not-found page. ROM sets and model support differ by variant; a full port test requires a separately bought or built harness.

Breaks a compatible Commodore A/V port out to S-Video, composite video, stereo SID audio, and a stereo mini-jack.

For this system (exact model): The maker explicitly lists the SX-64. The C64 OS hands-on feature warns that the adapter covers controller port 1 on this system, so verify clearance and whether that port is needed.

The maker showed four V2 units in stock with a working cart path on 2026-07-29. Early C64 Assy 326298 machines use a five-pin video socket: composite output works, but S-Video does not. The optional SID-ground noise-reduction jumper must not be enabled on an Ultimate 64 board.

Connects a Commodore expansion port to external MIDI equipment through MIDI In, Out, and Thru sockets.

For this system (exact model): The seller explicitly names the SX-64. Confirm cartridge clearance, software support, and any expander arrangement before combining it with another cartridge.

Human review confirmed on 2026-07-28 that the linked seller item is currently orderable. The seller says the cartridge includes instructions; Cynthcart, an expander, software, and MIDI cables are separate.

Adds four 8-bit digital audio channels with stereo output through the Commodore user port.

For this system (exact model): The detailed C64 OS feature explicitly names the SX-64. Confirm physical user-port clearance, software support, and external audio routing on the portable system.

The Shareware Plus page was last updated on 2025-08-01 and then claimed email ordering, but it exposes no conventional store or current checkout path. HR-061 confirmed that the original maker URL is gone and closed with direction to stop pursuing the unread Mk2 path for now. Availability remains unknown; PCBWay says the author stopped sharing the Mk2 there.

Modern VIC-1011-style user-port RS-232 adapter with status lights, reset, and a software-dependent 9600-baud mode.

For this system (exact model): The seller explicitly lists the SX-64, but does not provide a model-specific installation procedure.

Tindie marked the adapter out of stock on 2026-07-30 and says it has been sold out since 2026-01-05. A DB25-to-DB9 adapter is an optional passive accessory, not a separate catalog product.

FPGA-based pin-compatible 6581 and 8580 replacement with two complete SIDs, six-voice stereo, analog inputs, paddles, and mouse support.

For this system (exact model): The maker explicitly supports the SX-64 and provides an SX-64 installation video. Use that procedure because its internal layout and cable routing differ from a desktop C64.

Human review confirmed on 2026-07-28 that the advertised KryoFlux store item is gone. The project documentation, firmware, and configuration software remain available, and used units can still be searched for. An interrupted firmware update can require JTAG recovery.

User-port USB serial adapter for linking supported Commodore 8-bit computers to a modern host's virtual COM port.

For this system (exact model): The seller explicitly lists the SX-64 as compatible.

The Tindie seller was taking a break on 2026-07-30 and did not expose an ordering path. GGLABS publishes a schematic, but the page does not present a complete fabrication and assembly package.

DIY replica of the 1985 C64 freezer cartridge that captures RAM, I/O, and CPU state to disk.

For this system (exact model): The original manual gives a specific SX-64 workflow: use the internal drive-reset button when the ordinary instructions say to power-cycle the disk drive. The cartridge still needs its prepared system disk and exact switch sequence.

The replica repository's 2021 v1.0a files include ISEPIC-named Gerbers, an Altium PCB project, schematic, bill of materials, and disk images. Its README mistakenly links its PCBWay order button to a different 8 MHz Z80 card; do not order that board as an ISEPIC. Review and fabricate from the included ISEPIC files instead. Replica hardware files outside the Docs and Software directories are CC BY-NC-SA 4.0. The original 1985 ISEPIC software remains copyrighted and is not covered by that hardware license.

Current FPGA replacement for MOS 6526 and 8521 CIA chips with selectable old- or new-CIA behavior.

For this system (exact model): The maker explicitly tested the SX-64. Confirm socket orientation, internal clearance, and RF-shield insulation before applying power.

The official project page links multiple current retailers, and AmericanRetro exposed a direct Buy Now route on 2026-07-30. The maker says the implementation passes its diagnostic and software suites but explicitly warns that a reproduction cannot be guaranteed identical under every hardware and software combination. Clockwork64's maker separately reports problems with J-CIA replacements.

Current FPGA replacement for MOS 6510 and 8500 processors, including the documented instruction set and cycle behavior.

For this system (exact model): AmericanRetro explicitly lists tested SX-64 support. Inspect the existing CPU mounting and internal clearance before installation; the direct drop-in claim assumes a usable socket.

The official project page links three current retail channels, and AmericanRetro exposed a direct Buy Now route on 2026-07-30. The retailer describes a same-size, no-soldering drop-in replacement; that assumes the original CPU is already socketed. A soldered CPU still requires proper desoldering and a suitable socket.

Licensed replacement computer and disk-drive ROM system that accelerates Commodore serial storage and adds DOS commands.

For this system (exact model): The official site identifies the SX-64 and publishes a dedicated installation guide. Match the licensed ROM set and installation method to the internal computer and drive hardware.

The official licensing site listed five authorized sales channels on 2026-07-27. Offerings include licensed ROM images, replacement ROM overlays, and switchless overlays; stock and the exact supported machine or drive vary by seller.

Swaps both Commodore 64 control ports at the press of a button without moving the connected controllers.

For this system (exact model): The seller reports successful SX-64 testing. Confirm physical clearance around both control ports before ordering the bare or cased version.

The no-case version showed four units in stock at EUR 32 on 2026-07-30. The listed range through EUR 42.90 includes the optional black 3D-printed case. A brass standoff supports the board while its illuminated button is pressed.

Intercepts the C64 keyboard matrix to add programmable shortcuts, macros, remapping, remote control, and sixteen hardware-control lines.

For this system (exact model): The documentation explicitly provides a slow scan mode for the longer cable used when installing Keyman64 in an SX-64. Confirm internal mounting, cable construction, grounding, and shared power before installation.

The maker currently offers revision 4 assembly kits with a PCB, preprogrammed ATmega, and components except connection cables for EUR 30 by email. Kits are made in small spare-time batches and may require prepaid backordering. Version 1.6 firmware, configuration tools, Gerbers, KiCad design files, schematics, and source remain downloadable.

Open SwiftLink-compatible expansion-port UART design for connecting supported Commodore computers to DB9 RS-232 equipment.

For this system (exact model): The maker explicitly lists the SX-64. Check physical cartridge clearance and choose an I/O bank that does not conflict with other installed hardware.

RETRO Innovations does not sell assembled Link232 cartridges. The maker publishes EAGLE schematic and PCB files for builders. A separately mentioned future Turbo232-compatible revision has no documented release and is not part of this record.

VIC-II interposer combining LumaFix video cleanup with a replacement C64 clock-generator circuit.

For this system (exact model): The current Protovision compatibility list explicitly names the SX-64. Confirm internal height and heat-shield clearance before installation.

Protovision listed the PAL LumaTOLB at 25 EUR but temporarily unavailable with unknown delivery time on 2026-07-30. The current listing gives a three-year warranty and says the original timing chip need not be removed. Installation may require replacing the VIC-II heat shield with a larger one. A hands-on 2018 report says LumaTOLB does not work with C64 Reloaded MK2, although the separate original LumaFix does. No current NTSC order path was verified.

Compact two-connector cartridge-port expander with an upright slot and reset button for C64-family computers.

For this system (exact model): The current Mini X-Pander+ listing explicitly names the SX-64. Confirm physical clearance and cartridge compatibility before use.

Protovision showed 12 Mini X-Pander+ units in stock with a one-to-two-week shipping estimate on 2026-07-27. The seller explicitly says it is not compatible with the 1541 Ultimate 2. Two enabled cartridges must use compatible bus signals and different address ranges.

Combines an integrated MIDI interface with five cartridge-resident SID music applications for sequencing, synthesis, drums, and low-fidelity sample playback.

For this system (exact model): The official availability and FAQ pages explicitly support the SX-64. Its built-in display and drive can provide the required screen and storage, but verify expansion-port clearance and the drive device number when combining other peripherals.

The official contact page reported MSSIAH in stock on 2026-07-28, and its online order workflow was live. The cartridge and software are one integrated product: its MIDI hardware cannot be used by other applications, no MIDI OUT is provided, and the ROMs are not sold separately. A monitor is effectively required, and saving needs a compatible drive or separate Savyour.

Current flashable C64 freezer and development cartridge compatible with Retro Replay, Action Replay, and Nordic Power ROMs.

For this system (exact model): The maker says Nordic Replay is functionally identical to Retro Replay except for its added mapping mode, and the Retro Replay hardware page explicitly records successful SX-64 testing. Check cartridge clearance and use software appropriate for the SX-64's integrated drive.

individual Computers marked Nordic Replay available for immediate delivery on 2026-07-30 as a fully assembled and boxed cartridge with the Retro Replay ROM pre-flashed. iComp supports the hardware but not the third-party ROM software. Action Replay compatibility does not supply an Action Replay ROM license; the maker says an owner may use an image from an original cartridge. The accessory connector is documented only for compatible devices such as Silversurfer, RR-Net, and MP3@64, and the technical page warns that incorrectly fitted hardware can short and destroy both devices.

Adds a switch-selectable 256 KB to 16 MB DMA RAM Expansion Unit compatible with Commodore 1700, 1750, and 1764 software.

For this system (exact model): The current product page explicitly includes the SX-64 among the supported computers.

RETRO Innovations exposed an Add to Cart path at $75 on 2026-07-27. A dated 2026-04-29 notice on the product page says red enclosures were temporarily unavailable and orders could take two to three weeks to ship, so confirm the current enclosure and fulfillment state when ordering.

Family of IEC storage devices that lets supported Commodore computers access files and disk images on SD or other removable media.

For this system (exact model): Current NC92 and Retro Lemon variants explicitly list the SX-64. Retro Lemon's version takes power from the user port. Confirm connector clearance and choose a unique IEC device number for use alongside the internal drive.

Retro Lemon listed its user-port-powered C64, C128, VIC-20, and SX-64 variant in stock at GBP 34.17 on 2026-07-27, and Sordan exposed a current Buy now path for its combined SD2IEC and Tapecart variant. PolyPlay's plain external Sordan Micro device and Retro Electronics' internal board were out of stock, while the RetroFletch backplane seller was on a break. A complete open C64 SD2IEC LP hardware build is also available. Variant power, connectors, controls, and firmware configuration differ. The official firmware site says 0.x firmware is obsolete and warns that newer-dated bootloaders are not necessarily safer or better.

Partially assembled internal board for adding a second matching SID chip at $DE00 or $DF00.

For this system (exact model): MSSIAH lists PAL and NTSC SX-64 compatibility, but its installation manual covers the standard C64 rather than an SX-64-specific route. Verify internal access, socket clearance, chip-select wiring, and audio routing before assembly.

The MSSIAH availability page reported the SID2SID circuit board in stock on 2026-07-28, and its order workflow includes SID2SID. SID chips, audio wiring, and an output jack are excluded. Shareware Plus separately advertises a parts pack without the PCB or SID chips while its remaining stock lasts.

Adds one or two original SID chips with automatic model detection, selectable mono or stereo addressing, protected power, and a dedicated stereo output.

For this system (exact model): The maker explicitly lists the SX-64 and supplies a longer cable set. SIDFX replaces the incorrect filter-capacitor arrangement found in the SX-64, but installation still requires user-supplied SID chips and the model-specific manual prerequisites.

The official site reported the SIDFX bundle sold out on 2026-07-27 and says no more modules will be manufactured after its limited stock is exhausted. The separate C64 Reloaded MK1 and MK2 adapters are accessories for this same family and do not replace the unavailable SIDFX module.

Internal stereo SID card sold for several C64-family computers with a connection cable and configuration jumper.

For this system (exact model): The seller explicitly lists the SX-64. The public page does not document the model-specific internal installation, cable routing, or clearance requirements.

poly.play and human review reported the card out of stock on 2026-07-28. HR-056 found no additional public setup information, so confirm the required SID chips, addressing, voltage configuration, and installation procedure before obtaining old stock.

Installs inside supported Commodore floppy drives to duplicate protected disks and add disk utilities.

For this system (exact model): The broader Supercard+ listing explicitly includes the SX-64 drive. Installation is internal and may require desoldering the drive's 6502, so read the supplied instructions before opening the computer.

Both assembled variants were out of stock on 2026-07-24. Each listing includes a 40-pin socket and version 6.0 software on two 5.25-inch disks. Some drives require desoldering the 6502 and installing a socket, so identify the drive model and board revision before ordering or installing.

Replaces a C64 or SX-64 KERNAL ROM with 36 selectable ROM or program slots, file browsing, firmware updates, and optional WLAN and FTP access.

For this system (exact model): The manual specifies the 24-pin assembly for SX-64 KERNAL ROM part 251104. Optional GPIO wiring can change the internal drive number. Confirm socket access, module clearance, and any internal wiring before buying a used unit.

No current official retailer or reproducible fabrication package was verified. A July 2026 hobby report says units had reappeared on Kleinanzeigen, so treat SuperKernal as used-market hardware and verify that the module, WLAN board, headers, firmware, and documentation are included. Supply only ROM images you are licensed to use.

Uses the SX-64's existing drive-reset button to reset the computer, change drive numbers, and switch ROM sets.

For this system (exact model): The board is specifically for the SX-64 and reuses the reset button behind its front control door. Installation requires opening the computer and soldering. Read the complete manual first, and use the TFT-specific variant only with the linked TFT conversion.

All three official variants were in stock on 2026-07-30: the assembled and tested board at USD 19.95, the easy-to-build kit at USD 9.95, and the bare-parts and programmed-CPU TFT version at USD 6.95. The standard assembled board is the simplest option. Installation still requires opening the SX-64 and soldering; the TFT variant is only for the separately documented TFT conversion.

Combines ROM and program loading, MIDI, Ethernet, NFC launching, remote control, a real-time clock, and REU functions in a Teensy 4.1 cartridge.

For this system (exact model): The maker explicitly lists the SX-64 among validated machines. Confirm cartridge clearance and provide any removable storage or USB peripherals required for the intended functions.

The maker's Lectronz store showed six fully assembled revision 0.4 units at USD 64.00 on 2026-07-27. The programmed Teensy 4.1 and case are included. A CR1225 battery is included only with United States shipments, and an SD card or USB drive is needed for content beyond the built-in files.

Combines a C64 accelerator, VGA output, REU and GeoRAM memory, SD storage, dual 1541 emulation, input adapters, and cartridge emulation in one FPGA cartridge.

For this system (exact model): The developer FAQ says Turbo Chameleon is fully compatible with the SX-64. On some SX-64 machines, copying the KERNAL ROM can fail; disable that option if the copied KERNAL does not work.

Individual Computers listed Turbo Chameleon V2 out of stock at EUR 235.44 on 2026-07-27. The official firmware remains in beta, with current releases and known bugs maintained in the product wiki. A CR1220 battery, networking card, docking station, cables, power supply, keyboard, and monitor are not included unless separately stated.

Connects modern Bluetooth gamepads and, on selected models, mice to Commodore, Amiga, and Atari computers.

For this system (exact model): The maker explicitly lists the SX-64 as supported. Confirm physical clearance and power arrangements for the selected board or third-party build before ordering.

The official C64, A500, and 800XL Tindie pages were out of stock on 2026-07-30, although the project marks those models active and supported. CBMretro had equivalent cased C64/C128 and A500/A1200 hardware available at EUR 41.90; the original designer does not support third-party builds. Open hardware, firmware, and documentation remain available. The guide's original Unijoysticle tile is folded here as the retired WiFi predecessor: it needed a separately powered ESP8266 receiver and phone or desktop client, unlike the Bluetooth successor.

Adds Wi-Fi BBS and Hayes-modem access through the user port of supported Commodore computers.

For this system (exact model): The official manual names the SX-64 and installs the standard WiModem through its user port.

The standard display-free version and both PET versions were out of stock on 2026-07-30. The standard OLED page still said a new design was pending and did not offer ordering. Check the direct pages for a restock or revised design.

Open cartridge-port expander with three independently controlled positions, configurable bus signals, and a reset switch.

For this system (exact model): The maker explicitly lists the SX-64 but discourages this combination because its expansion-port ribbon cable further degrades signals and can make the expander unusable.

The official store exposed an active $30 listing on 2026-07-27, and the open Eagle files remain available. Cartridge combinations are not guaranteed, the two connectors at the third position share one set of switches, and the passive bus can worsen marginal signal integrity. Insert, remove, and configure hardware only with the computer powered off.