All upgrade products

Translates a PS/2 mouse into Commodore 1351-style analog mouse signals for the C64 and C128.

Retro Computer Store listed an assembled adapter as available for USD 16 on 2026-07-30. PCBWay exposes a through-hole fabrication route with Gerbers, a bill of materials, and programming notes. The current assembled version supports PS/2 mice and PS/2-compatible serial mice but explicitly does not support a USB mouse through a passive PS/2 adapter. A working SID analog-input path is required; some replacement SID implementations omit it.

Upgrades an Atari 1050 disk drive for divisor-6 high speed, 180 KB per side, and flashable firmware slots.

Lotharek marks 1050E discontinued. The seller calls installation solderless, but it still requires opening the drive, removing three chips, moving the 6507 CPU, and preserving socket orientation. Confirm that a used kit is complete, that all original chips and sockets are healthy, and that suitable 1050E firmware and host software are available.

Recreates an Atari 8-bit computer on a Mini-ITX motherboard with integrated memory, input, mouse, and video upgrades.

The maker publishes schematics, a BOM, production Gerbers, firmware, and PCB source files. The page points to The Brewing Academy for boards and systems, but current assembled stock was not checked in this pass.

Selects which 1088XEL joystick port receives input from its PS/2 mouse.

The maker publishes a schematic and Gerbers and links to both bare-PCB layouts at OSH Park. This is a self-built selector rather than a current assembled product; the generic layout requires suitable LED and switch openings in the chosen case.

Recreates an Atari 8-bit computer for an Atari 1050 case with integrated IDE storage, expanded memory, PS/2 input, video, stereo audio, MIDI, and expansion.

The maker publishes schematics, a BOM, firmware, panel files, and production Gerbers. The project page links to The Brewing Academy for boards and assembled systems; verify current stock on the seller page.

Replaces the Atari 1200XL memory subsystem with 1088 KB of SRAM.

The maker publishes a schematic, Gerbers, and the programmed-logic JED file but no bill of materials. The installation removes twelve socketed chips from the motherboard and transfers four original chips to the upgrade. The RF choke may need to be bent or removed for clearance. Install the 1 mm board only with the motherboard out of its case and supported on a solid surface because the stacked machine-pin sockets require substantial insertion force.

Runs a cartridge-resident suite of health, speed, alignment, sector, and command tools for 1541-family floppy drives.

Protovision listed 22 units at EUR 25 with a one- to two-week shipping estimate on 2026-07-30. Jani also publishes free cartridge images for device 8 and device 9. The software alignment display is a health indicator, not a substitute for a factory analog alignment disk and oscilloscope.

Adds one or two modern 115200-baud serial ports supported by RomWBW.

Current listings cover one-port and two-port layouts for Standard or Enhanced Bus. RomWBW 3.4 supports the hardware, with 0xA0 or 0xA8 used for added ports; 3.5 and later also support 0x80 and 0x88. More than four serial ports needs a custom RomWBW build.

Replaces a Commodore 2364 ROM with a readily available 27C64, 27C128, 27C256, or 27C512 device.

The product selector offered all three build levels on 2026-07-25. The included W27C512 option is blank; the buyer must provide and program an appropriate ROM image.

Exposes two or four independent output channels from the Apple IIgs Ensoniq sound chip.

The 2soniq was available on backorder and the 4soniq was in stock and backorderable on 2026-07-24. Two-channel output works with most IIgs software; four- or eight-channel use requires software written or modified for those modes and enough powered speakers.

Adds external VGA to an SE/30 or IIsi, with selected SE/30 variants also driving the internal CRT in grayscale.

Juicy Crumb showed the complete $949 SE/30 Greyscale Kit out of stock on 2026-07-27, and the developer page exposed no separate public order path for current external-only cards. The nonstandard 1024 by 768 at 54 Hz mode will not sync on every display. Extra PDS cards can cause instability, and the maker warns that adapting VGA output to a vintage Apple CRT may damage the monitor.

Adds up to the Z80's full 64K addressable RAM with selectable start address.

Current kits are offered with 32K or 64K and Standard or Enhanced Bus headers. The listing is for the memory module only; a CP/M setup also needs the documented Pageable ROM and other core modules.

Adds 4 MB of DMA-compatible memory to a ROM 01 or ROM 03 Apple IIgs.

Human review confirmed that the product page was in stock on 2026-07-24. The page describes kit and assembled variants, but the answer did not distinguish the stock state of each selector option.

Adds banked memory for running RomWBW, CP/M, and Z-System.

The current kit is the memory configuration used by RC2014 Zed and Zed Pro. It replaces both separate ROM and RAM modules in a Classic II or Pro; a Mini can use it only after its onboard ROM and RAM chips are removed.

Recreates an Atari 8-bit computer on a compact 4.5-inch motherboard with 576 KB of RAM, PS/2 input, selectable ROMs, and modern daughterboard expansion.

The maker publishes Gerbers, schematics, a BOM, firmware, and case files, and points to The Brewing Academy for assembled systems and boards. The current project page requires a documented oscillator video fix on existing builds.

Raises an Atari 600XL from 16 KB to 64 KB with a compact external parallel-bus module.

The page reported four modules in stock on 2026-07-27. The 600XL supplies the required 5 V through its parallel bus, so this exact module needs no external power supply.

Provides 64 KB of main RAM and 256 KB of RAMBO-compatible extended memory through a 1090XL-family expansion slot.

The page reported three cards in stock on 2026-07-27. A 1090XL or 1091XL base system is required and is not included. The PBI-memory option must remain off when the host has VBXE or Ultimate 1MB. The RAM-disable option is recommended for modern reproduction systems so other cards can map their own memory.

Provides 80-column text over HDMI from a Raspberry Pi Pico card installed in a 1090XL-family expansion system.

The page reported three cards in stock on 2026-07-27. A 1090XL or 1091XL base system and a separate HDMI display are required. Enabling the card disables normal video output; holding Shift while booting disables the card. Each installed expansion card needs its own jumper-selected device ID.

Connects an Atari CX-85 numeric keypad through a 1090XL-family expansion slot with an onboard input handler.

The page reported two cards in stock on 2026-07-27. A 1090XL or 1091XL base system and an Atari CX-85 keypad are required. Current compatibility is limited to software that obtains input through the Atari operating system.

Adds five 1090XL-family expansion slots to an Atari 600XL or 800XL through the rear parallel bus.

The page reported one system in stock on 2026-07-27. The 50-pin parallel cable is included, but a compatible 9 VAC Atari power supply is not. Expansion cards and the optional 12 V supply configuration cost extra; the seller says no currently available card needs that optional 12 V rail. Systems are assembled on demand and may take several days to ship.

Adds Hias high-speed SIO and Fast Math F+ through a 1090XL-family expansion card.

The page reported two cards in stock on 2026-07-27. The sale includes only this card; the 1090XL-family base system and the separately pictured CP/M card are not included.

Adds an 8 MHz-or-faster Z80, 64 KB of onboard memory, and a beta CP/M environment through a 1090XL expansion slot.

The page reported one card in stock on 2026-07-27. CP/M customization and utilities remain late beta. The card is sold with or without a Z80; a user-supplied CPU must be rated for at least 8 MHz. The pictured 80-column RPP card is optional and not included. Double-density disk use also requires supporting drive hardware. The exact page names only the 1090XL, so confirm 1091XL compatibility before using it in that implementation.

Moves the Atari 1200XL cartridge slot outside its recessed tunnel and adds switchable OS 6.42 and BASIC firmware.

The page reported three cards in stock on 2026-07-27. OS 6.42 adds bug fixes, high-speed SIO, faster floating point, CX-85 handling, WozMon, and cassette improvements. Its activity LEDs do not work when the computer has more than 64 KB, and some software is incompatible because the replacement OS runs from RAM; the front switch disables that OS when needed. Only the card is included.

Replaces the Atari 1200XL's model-specific C060609 memory-management chip with a programmed modern logic device.

The page reported two units in stock on 2026-07-27. This listing is specifically a replacement for Atari part C060609 in socket U14 of a 1200XL. Do not treat the seller's general explanation of MMUs across the Atari 8-bit family as compatibility with other models.

Expands an Atari 600XL or 800XL to 320 KB through the rear parallel bus without opening the computer.

The Tindie page reported one unit in stock on 2026-07-27. A 600XL supplies power through its parallel bus. Most 800XL computers do not, so the board provides a jumper-selectable USB-C or wired 5 V input. Follow the seller's internal-versus-external power procedure and jumper setting for the exact computer.

Rebuilds an Atari 800XL around a newly manufactured Revision 1.2 motherboard with bare, programmed-chip, and assembled options.

The main board page reported two units in stock on 2026-07-27. A completed board requires the buyer to send a functional, non-returnable donor board because original Atari chips and some connectors are no longer made; the seller estimates about two weeks for completion and testing after receiving it. The separately orderable programmed-chip page reported four sets in stock. Its EMMU must match the intended memory configuration and is optional for a 64 KB-only build.

Replaces the Atari 400's internal RAM board with either 48 KB or 1056 KB of modern memory.

Both product pages reported five boards in stock on 2026-07-27. Either installation requires disassembling the computer and soldering four jumper wires beneath the main board. A machine previously fitted with Atari's 48K RAM Expansion Kit may already have those jumpers. The 1056K board does not require the plastic-housing modification described in the older Atari kit instructions.

Replaces the Atari 800's plug-in memory modules with either 48 KB or 1056 KB of modern RAM.

Both current pages exposed active ordering on 2026-07-27, and the 1056K listing reported four boards in stock. Installation does not require soldering, but the computer's top cover and existing memory modules must be removed. Both supplied boards have a marked keyboard-facing orientation; reversing either one can damage the computer or memory board.

Tests major Commodore 64 chips, ROMs, interrupts, controls, and external ports with a cartridge and loopback plugs.

Protovision announced that 64 Doctor was back in stock on 2026-07-21. The product page listed eight units at EUR 35 with a one- to two-week shipping estimate on 2026-07-30. A detailed 2019 review identifies Tim Harris of Shareware Plus as the licensed manufacturer and demonstrates the test sequence, but it does not establish equivalent sound-test behavior for an 8580 or replacement SID, the SX-64, or a C128 in C64 mode.

Safely translates Sega, NES, SNES, or legacy analog PC controllers for Commodore, Amiga, and Atari-style control ports.

The official page still displayed order instructions and prices from USD 14.95 for the chipless protection version through USD 36.95 for a combo interface with an adapter on 2026-07-30. However, its prominent post-COVID shipping notice and 2021 copyright are stale, and it says only that most items remain orderable. Contact 64HDD for exact version, stock, price, and postage before sending payment. SNES-to-JPX and PCanalog are companion adapters and remain in this product family.

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

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.

Replaces the CPU in Commodore 264-series computers and can add 512 KB of Hannes-compatible expanded memory.

Lotharek marks the module discontinued. CPU-only use requires correct pin-1 orientation and a compatible socket or safe desoldering. Enabling the 512 KB expansion is invasive: remove the original DRAM and connect CAS to pin 15 on an eight-chip, 1-bit layout or pin 16 on a two-chip, 4-bit layout. Confirm the exact motherboard, CPU package, memory layout, and software's Hannes banking support before buying or installing a used module.

Adapts a W65C816 processor to a 65C02-compatible socket while generating the missing clock and synchronization signals.

The board was out of stock on 2026-07-24. It adapts processor signals but does not provide an independent accelerator clock; the stated 14 MHz is a board capability, not a promise that an Apple IIc will run at 14 MHz. Confirm socket type, clearance, and host timing before installation.

Adds stereo 8-bit audio sampling hardware to a Commodore 64.

The seller page was last updated on 2025-01-01 and then claimed stock by email, but Shareware Plus exposes no conventional store or current checkout path. HR-060 closed with direction to stop pursuing that stale sale claim, so availability remains unknown. The seller also says it does not know which software works and that the project did not progress beyond the hardware release.

Current composite and S-Video cable options for compatible Commodore computers, with a five-pin composite branch that also serves selected Atari systems.

The two five-pin products exposed Add to cart controls, while the eight-pin product exposed current priced options on 2026-07-30. The five-pin cable and adapter carry composite video and two audio connectors; those connectors do not create an independent stereo source in a stock mono computer. The eight-pin S-Video branch requires a host that supplies separate luma and chroma. Its stereo option requires a compatible second audio source on the designated extra pin. Match the connector, resistor, audio wiring, display input, and regional video standard before ordering.

Adds a directly programmed 8x8 LED display for graphics and animation.

Current kits offer several red, blue, or white display styles, or no matrix. A diffuser is included. Other 32x32 mm, 16-pin common-cathode matrices can be used if their electrical and physical layout matches.

Adapts a modern PicoPSU and external power brick to the Apple II, II Plus, and IIe.

Human review confirmed that the required A2 ATX core unit could be ordered on 2026-07-24, resolving the conflicting stock displays on the build-a-kit and standalone pages. The optional JCM power lead was also in stock, but it is not keyed and installing it backwards can destroy the power supply, computer, and attached hardware.

Connects and switches among four Apple II-compatible joysticks through a computer's external DE-9 game port.

JCM showed two adapters in stock on 2026-07-24. The host connection is DE-9 only: despite accepting two 16-pin controllers, the adapter cannot connect to a computer's internal 16-pin game socket.

Converts the digital video expansion signals from an Apple IIc-family computer or Laser 128 to an HDMI-compatible output.

JCM showed 10 assembled units in stock on 2026-07-24. The product uses an HDMI-compatible connector, but the source does not claim audio output or universal display compatibility. Power down before attaching or removing vintage-computer video adapters.

Generates digital video from Apple II display memory through an HDMI-compatible connector.

JCM showed 22 v2.0 cards and 20 v4.4 cards in stock on 2026-07-24. On an Apple IIgs, A2DVI displays only legacy Apple II modes; 320- and 640-pixel Super Hi-Res applications do not appear on its output. A v4.4 card runs only one selected firmware function at a time.

Combines 480p HDMI output, Apple II and Mockingboard audio, and several video expansions on one FPGA-based card.

Human review confirmed that the vendor product page offered a current ordering path on 2026-07-15.

Uses a phone, tablet, or laptop as a bridge from modern wireless controllers to an Apple II game port.

The authorized ReActiveMicro listing was out of stock on 2026-07-24, and CT6502's former product URL returned 404. The maker information and manual remain available.

Connects a 9-pin Apple II joystick or A2io receiver to the internal 16-pin game I/O socket.

CT6502 marked A2jc out of stock on 2026-07-24. The direct product page remains available for setup instructions and restock notification.

Open hardware and software platform for building Raspberry Pi Pico-based Apple II peripheral cards.

JCM showed 36 assembled A2Pico cards in stock with selectable preinstalled firmware on 2026-07-24. Choose the board and firmware together. The simpler A2Pico2Lite design uses a Pico 2 and omits the original A2Pico microSD slot. Unpowered USB OTG hubs can cause device problems, especially with mice.

Recreates Apple's Revision C SCSI card with termination power and onboard active termination for improved drive compatibility.

The GGLABS Tindie store says the seller is taking a break and offers a return notification rather than a current order path. The project page provides software and technical material, but says parts of its pseudo-DMA and IIgs-mode schematic documentation remain incomplete.

Repurposes supported Raspberry Pi Pico Apple II video cards as a USB HID mouse interface.

A complete setup needs a supported A2VGA Revision 1.6 or modified older A2VGA or A2analog card, a Micro-USB-to-USB-A adapter, and a driverless USB HID mouse. USB hubs are not supported. Installing A2USB removes the card's VGA function until different firmware is loaded. Remove the Pico or card from the Apple II before using BOOTSEL to update firmware, and choose the PAL or NTSC build with the appropriate 50 or 60 Hz interrupt default.

Adapts a modern PicoPSU and external power brick to the Apple III and Apple III Plus.

The build-a-kit page showed the core, switch, PicoPSU kit, and non-destructive power lead in stock on 2026-07-24. Buyers must select the complete set of required components rather than treating an inexpensive switch or lead as a full replacement.

Open 68060 processor card for Amiga 3000 and 4000 computers.

AMIGAstore warned that only the last assembled units remained on 2026-07-24. Rabbit Hole Computing's bare PCB listing was sold out. Building from the GPL-licensed project files is an advanced assembly requiring the processor, programmed logic, connectors, and the rest of the bill of materials.

Adds 8 MB of Fast RAM and a bootable 44-pin IDE controller at the Amiga 500 CPU socket.

The assembled Lotharek revision exposed a login-or-register-to-buy path on 2026-07-27; the original Oleg Mishin design files, ROM, firmware, software, and four-layer PCB are public. The box contains only the board. Kickstart and Workbench 1.3 or newer can autoboot without a patched scsi.device. A socketed CPU makes installation simple, but an unsocketed CPU must be desoldered. Pin 1 must be observed when attaching CF or SD hardware because a reversed adapter can destroy the CPLD. The open repository documents the original A500 design, while the current seller alone claims A500 Plus support for its revised hardware.

Adds 512 KB of trapdoor RAM and a real-time clock to an Amiga 500 on a compact newly made board.

The product page exposed a login-or-register-to-buy path on 2026-07-27 but supplies only the Amiga 500 purpose, 512 KB capacity, RTC function, and photographs. Human visual review confirms that it plugs into the trapdoor expansion. The RTC chip, backup-cell design, clock setup, memory mapping, motherboard and Agnus limits, and Amiga 500 Plus behavior remain unpublished, so the catalog retains only the exact Amiga 500 relationship.

Loads cartridge images and XEX files from USB-managed flash storage through an inexpensive RP2040-based Atari XL/XE cartridge.

A8Renegade's live Shopify product data and collection reported the assembled cartridge orderable on 2026-07-27, despite a contradictory sold-out label in the rendered product page. The complete open design also remains buildable.

Combines a new custom Atari 8-bit motherboard, 576 KB of memory, UGV II video, and a refurbished original Atari 130XE case and keyboard.

The exact product page reported sold out on 2026-07-27. The broader collection page disagreed, so check the exact listing for a restock.

Combines a new custom Atari 8-bit motherboard, 576 KB of memory, and monitor output with an original Atari 600XL case and keyboard.

The live Shopify product data and current catalog reported the complete unit orderable on 2026-07-27. It uses a cleaned original Atari 600XL case rather than a newly made enclosure.

Retains the original POKEY while adding FPGA stereo POKEYs, Covox channels, digital mixing, and a high-rate stereo DAC.

The product exposed a login-or-register-to-buy path on 2026-07-27. It requires a working original POKEY and can be installed in stages: basic stereo output, a second POKEY through an A4 connection, Covox through D6xx or D7xx decoding, and full internal-audio mixing. The approximately 1 mm PCB intentionally leaves pin 31 unconnected; verify that it remains isolated from the motherboard. Only the basic stage uses a single address jumper, while the expanded functions require additional signal and audio wiring.

Uses an STM32 and SD media as a mature open Atari ST hard-drive emulator with ACSI, disk-image, and GemDrive modes.

The upstream project describes hardware and software version 5.00 as finished and mature. Its release package contains files for ordering a compact board with assembly, but the builder must flash it initially with a 3.3 V-compatible USB-to-UART adapter and supply 5 V USB-C power, media, and an optional CR2032. Firmware 1.x, 2.x, and 3.0-or-later boards have different compatibility paths; the current compact design should use the matching current firmware. Lotharek's separate four-slot ACSI2STM Redux case design remained not yet available on 2026-07-27 and is not represented as a current assembled seller.

Bidirectionally converts keyboards and mice between Apple's ADB interface and modern USB HID.

The BMOW store showed the Wombat as sold out on 2026-07-14. Check the direct product page for a restock.

Recreates the circa-1990 AdLib OPL2 FM-synthesis sound card as a buildable open hardware project.

This is a self-assembly reproduction rather than a currently sold assembled card. The repository has no packaged release; use the project files and parts list directly.

Period 5 MHz 8088 coprocessor card with optional fast memory and an 8087 socket.

This is a period product obtained used. The AD8088 has 2K of onboard RAM expandable to 8K; larger programs need the separate AD128K in a nearby slot, and the AD128K cannot operate by itself. The original package included FTL math acceleration and the MET event timer. CP/M-86 and MS-DOS support depended on separately supplied operating-system software. A system needs at least 48K, a Language Card or equivalent, a disk drive, and a display. An 8087 may require extra cooling or an empty adjacent slot.

Recreates the ALF Apple Music Synthesizer for composing and playing music from standard notation on an Apple II.

The A2Heaven clone is currently listed as out of stock. The store provides an archived ALF MC1 brochure from the product page.

Modifies an Amiga 1000 to boot Kickstart from four EPROMs while retaining access to its 256 KB daughterboard RAM.

This is an advanced board-level modification, not a plug-in board. It requires a GAL16V8A, four 27C512 EPROMs, a legally obtained Kickstart image, device programming, desoldering, jumper installation, and PCB trace cuts.

Replaces the Amiga 3000's ZIP-package Fast RAM with standard 72-pin SIMMs.

Rabbit Hole Computing marked the bare PCB sold out on 2026-07-24. The PCB did not include SIMM sockets, adapter pins, capacitors, resistor, LED, or SIMMs. Its linked project page now returns 404, so verify that a used board includes the build information and all required parts.

Upgrades a Revision 8A Amiga 500 motherboard to 2 MB of Chip RAM with a soldered internal module.

The product page exposed a login-or-register-to-buy path on 2026-07-27. It is only for Amiga 500 Revision 8A motherboards, requires soldering, and makes the trapdoor RAM expansion unusable. The current Revision 3 no longer needs the LSP connection shown on page 6 of the older fitting manual, so follow the current seller note rather than that obsolete step.

Recreates the Comspec SA-1000 sidecar to add a SCSI bus and real-time clock to an Amiga 1000.

This is a self-assembly project with a schematic, bill of materials, and fabrication package. It requires programmed GALs and ROMs plus careful alignment of the 86-pin edge connector. The alternate RTC-72421 clock chip is suggested but untested.

A current 1.5-meter five-pin DIN to SCART cable for several Commodore computer families.

The product page exposed a current Add to Cart path on 2026-07-30. The cable is 1.5 meters long and terminates in a five-pin DIN plug, so it does not carry the separate luma and chroma signals used for S-Video. Confirm that the intended display accepts composite video through SCART and that its regional video standard matches the computer.

Mounts a 44-pin SD-to-IDE adapter horizontally inside an Amiga 600 or 1200 and adds power, activity, and audible-access indicators.

The product page exposed a login-or-register-to-buy path on 2026-07-27. The box contains only the AmSider board; the SD-to-IDE adapter and SD card are separate. Pin 1 is marked beside the speaker and must be oriented correctly. The access buzzer can be disabled by opening its solder bridge.

Adds two configurable joystick ports, reset control, activity indicators, and an expansion pass-through to ZX Spectrum hardware.

Lotharek marks the interface discontinued and explicitly says it does not work on the Timex 2048. A used unit can contain first-release or later firmware with different mode choices and address decoding, so identify the firmware and test pass-through hardware before relying on it.

Replaces the Atari XL or XE operating-system ROM with a switchless 32-image OS selector and high-speed SIO features.

The official page showed self-installation and professional-installation options in stock on 2026-07-25. The generic kit is for XL and XE computers except XEGS; the special 1200XL kit includes an XE MMU and internal BASIC upgrade. The 1200XL procedure is an advanced modification that can require desoldering and replacing ROM sockets, moving jumpers, adding wires and a resistor, and modifying or omitting the RF shield.

Rebuilds the electronics inside an original Disk II drive with a cleaner analog path, keyed cabling, write protection, and easier head access.

CT6502 offered the two-board set for direct ordering on 2026-07-24. The boards are not sold separately.

Recreates the Apple Disk II controller card with modern components and selectable 16-sector or 13-sector firmware.

The current CT6502 catalog offered the assembled card for direct ordering on 2026-07-24.

Recreates Apple's controller for attaching 3.5-inch Apple floppy drives to slotted Apple II computers.

The controller was available on backorder with an Add to cart path on 2026-07-24. The page says all Apple II computers, but the product is an expansion card; slotless IIc models are not attached without separate interface evidence.

Published twelve-chip Motorola 6800 teaching coprocessor that takes control of the Apple II bus.

This is a published construction project, not a current kit or finished product. The paper supplies a circuit diagram and tested monitor listing but no PCB layout, Gerbers, bill of materials, or explicit reuse license. A builder must recreate the board, source period logic, program a 2716 EPROM, and validate timing and bus loading.

Published 1985 Apple II coprocessor prototype with a 68020, optional 68881, 32K SRAM, and boot EPROM.

Treat this as a historical experimental build, not a safe drop-in design. The creators used custom wire-wrapped and insulation-displacement construction rather than a published PCB. Later design notes estimate roughly 1 A typical and as much as 1.5 A from +5 V even though the Apple II specifies 500 mA shared by all peripheral cards, and they identify excessive data-bus loading. A faithful build needs its own engineering review and likely a redesigned power and bus interface.

Recreates a Passport-compatible MIDI interface for music software on Apple II computers.

The store showed one card in stock on 2026-07-24. A complete setup requires a 48K or larger supported computer, display, floppy drive and controller, compatible MIDI software, a MIDI instrument, and two 5-pin DIN cables.

Vintage 16K Apple II memory board with power, read, and write activity LEDs.

The MacEffects listing said Sold out on 2026-07-24. The board does not include its required 4116 memory chips. The original manufacturer and exact board model were not identified, so compare photographs and connector details before buying a used example.

Replaces an Apple II or II Plus motherboard with a complete Rev 7 RFI clone.

The current storefront exposed kit and assembled selectors on 2026-07-24. This changes an earlier Apple II to the later Rev 7 electrical and firmware configuration rather than preserving an original-revision board.

Provides a bare recreation of the original Apple II Revision 0 motherboard for restoration or a ground-up build.

The bare board was in stock and backorderable on 2026-07-24. It does not include the required components, ROMs, DRAM, assembly labor, or bring-up work.

Adds RGBS and SCART video output to supported Apple II logic boards.

The kit was out of stock on 2026-07-24. Installation differs by model and requires soldering inside the computer; follow the correct PAL or NTSC instructions.

Adds Software Automatic Mouth speech synthesis hardware to an Apple II.

The assembled card was out of stock on 2026-07-24.

Moves an Apple II peripheral card outside the case for repair, development, and testing.

The extender was out of stock on 2026-07-24. The vendor warns that longer ribbon cables may cause unreliable operation; use it only with power off while connecting or removing cards.

Lets supported original-style Apple II computers use a USB keyboard.

The adapter was out of stock on 2026-07-24. It supports only USB HID 1.0 low-speed keyboards, so many current USB keyboards may not work. The vendor explicitly says it is not compatible with the Apple IIe.

Converts Apple II, II Plus, Europlus, and IIe video for display on a VGA monitor.

The scaler is currently listed as out of stock. Because Apple II revisions differ, installation may require jumper settings and additional jumper wires; use the linked manual for the exact machine.

Modern microcontroller-based Apple IIc keyboard with mechanical switches, configurable backlighting, and a read/write activity indicator.

The MacEffects page said Sold out on 2026-07-24. The source explicitly names the Apple IIc and presents the board as a replacement for unreliable early hairpin-spring keyboards; it does not claim Apple IIc Plus fit.

Restores spring-clip keyboard support while leaving clearance for internal Apple IIc expansion boards.

JCM showed 39 units in stock on 2026-07-24. It is intended for the Apple IIc spring-clip keyboard. Some case revisions require trimming plastic screw bosses, so inspect the exact case before installation.

Replaces the power-supply PCB inside the Apple IIc Plus metal PSU enclosure with a modern universal-input supply.

The product was in stock and backorderable on 2026-07-24. Installation exposes mains-wired power-supply parts; disconnect the computer from AC power and follow the vendor guide exactly.

Improved firmware for the Apple IIc and IIc Plus, offered as a current ROM programming service.

Infinity Products listed its ROM 4X and ROM 5X flashing service without an out-of-stock marker on 2026-07-24. The open firmware project had a current March 2026 release.

Converts the Apple IIc family's digital video expansion output to 720x480 VGA.

The vendor page listed A2VGA as out of stock on 2026-07-24. Its 720x480 output may not work with some older VGA monitors. Earlier hardware was NTSC-only, so confirm the revision when buying used. Do not connect it to an Apple IIgs or Macintosh merely because those machines also have 15-pin video ports; the manual warns that doing so risks damage.

Upgrades an original Apple IIe with a 65C02 processor and the Enhanced IIe system and video ROMs.

The current page exposed selectable computer and video-ROM options with an Add to cart path on 2026-07-24. Select the 24-pin US or 28-pin European video-ROM option that matches the motherboard.

Modern full replacement keyboard for the Apple IIe using Matias ALPS-style tactile and clicky switches.

The MacEffects page said Sold out on 2026-07-24. The limited-production key legends can vary in darkness; choose a frame and keycap set appropriate to the computer.

Combines 8 MB of fast static RAM with an optional 512K boot ROM and built-in IIgs debugging software.

The card was out of stock on 2026-07-24. The optional ROM portion makes the assembly wider than a plain memory card; check clearance around long slot cards, especially in slot 7.

Connects an Apple IIgs serial port to MIDI instruments using Apple A9M0103-compatible software.

The interface was out of stock on 2026-07-24. It requires compatible MIDI software, a MIDI-equipped instrument, and two 5-pin DIN MIDI cables.

Converts a ROM 00 Apple IIgs to ROM 01 with a removable replacement ROM module.

The ReActiveMicro adapter was in stock and backorderable on 2026-07-24. Garrett's Workshop's alternative Tindie module was out of stock and had been sold out since August 31, 2024. These are ROM 00 to ROM 01 conversions, not ROM 03 upgrades.

Adapts Apple IIgs analog RGB and composite sync to a 15 kHz-capable VGA connector.

The adapter was in stock and backorderable on 2026-07-24. Most ordinary VGA monitors do not accept 15 kHz video; verify the exact display before ordering.

Supplies replacement capacitors for the Astec AA11190 and AA11190-B Apple III power supplies.

JCM showed 151 kits in stock on 2026-07-24. This kit is only for Astec AA11190 or AA11190-B supplies and requires safe mains-side power-supply repair skills.

Connects a Raspberry Pi Zero 2 W to an enhanced Apple IIe for virtual disks, networking, Linux commands, and file transfer.

The upstream project describes Revision 7 as a prototype rather than a finished product. Most development and testing used an enhanced Apple IIe with the card in slot 7; the firmware assumes the slot 3 80-column card and lowercase support. A Pi Zero 2 W can consume roughly 170 to 250 mA from the Apple II's 500 mA total slot budget. Revision 6 and later can use external USB power after the documented jumper change, but the firmware will hang if the Pi is not powered.

Generates crisp 640 by 480 VGA from Apple II video memory using a Raspberry Pi Pico bus-snooping card.

JCM showed 36 assembled A2 VidGA cards in stock on 2026-07-24, with firmware choices for Apple II and II Plus or Apple IIe. RetroFletch's A2 Analog seller was taking a break on 2026-07-27; its published board has a critical VGA IDC footprint error, so the cable's red wire must face the motherboard. A2 Analog can also conflict with some accelerators, card autodetection, CFFA3000, and ROMX configurations. Infinity Products' SMC A][ VGA Mini was out of stock, and Laser's assembled Mark Aikens variant showed zero stock. Choose the exact hardware and firmware branch rather than treating every variant as interchangeable.

Adds a reprogrammable, four-bank ROM adapter for ROM 0 Apple IIgs systems.

The adapter is currently listed as out of stock. It cannot convert a ROM 0 or ROM 1 Apple IIgs to ROM 3.

Provides ProFile-style block storage from a raw SD card for enhanced Apple IIe and Apple IIgs systems.

The repository publishes binaries, firmware, VHDL, schematics, layout files, Gerbers, and a bill of materials, but no explicit license was verified. Capacity is limited to four 65,535-block volumes, or about 128 MB total. Under ProDOS, programs on the third and fourth partitions have a documented launch problem. This is a build project rather than a current assembled product.

Connects a modern Mac to Apple and PC floppy drives for disk imaging, flux capture, analysis, and writing.

The official store marked Applesauce+ sold out on 2026-07-15. The client requires macOS 10.13 or later; Windows and Linux use requires macOS virtualization. Current boards use a 12V adapter, and the power adapter and PC-drive cables are sold separately. Flux imaging with Apple-compatible 5.25-inch drives requires a sync sensor, which is also strongly recommended for Apple 3.5-inch drives; PC drives do not need one.

Combines a 14 MHz 65816 accelerator, 14 MB memory expansion, HDMI output, RAM disk, and SD-backed drives for the Apple IIgs.

The regular AppleSqueezer GS v2 listing was out of stock on 2026-07-24. A separate preorder tile remained visible, but an active preorder order path was not verified; check the shop or mailing list for another production run.

Period slot memory and bootable RAM-disk card with optional expansion and battery backup.

This is the original period product, distinct from modern RamFactor-compatible cards. Used examples vary by board revision, installed memory, expander, ROM, and included software. It normally uses a peripheral slot other than slot 3; an Apple II Plus must not use slot 0. The IIgs treats it as RAM-disk storage rather than fast system memory. Verify any RamCharger, cable, and old battery hardware before applying power.

Period 3.6 MHz accelerator with a 65C02, 256K of high-speed memory, and optional 16-bit processor upgrades.

This is a period product obtained used and is distinct from TransWarp GS. Confirm the exact card revision, installed processor, diagnostics, and slowdown behavior before buying. The brochure says it works with most DMA cards, but a mixed vintage system still needs card-by-card verification.

Period internal Apple IIc card combining 256K or 512K of memory with a Z80 processor for CP/M.

This is a period internal card obtained used. The original package included RAM-disk software, a Z80 operating system, and CP/M documentation; verify that software and installation material are present. Opening the IIc and installing the board is required.

Adds adjustable CRT-style dark lines to a compatible progressive VGA signal before it reaches a modern display.

The ArcadeForge maker page remains online but exposed no clear current price or Add to Cart control on 2026-07-30. Arcade Express marked its unit out of stock, while Jammastar displayed both a last-items warning and a notify-when-available control. Confirm stock before ordering. The maker designs the device around 640 x 480 VGA. A stock C64, C128, or other 15 kHz computer cannot connect directly; it first needs a suitable scaler that produces a supported progressive VGA signal.

Provides a microswitch joystick with a classic 9-pin plug and autofire for the Commodore 64 Ultimate.

The direct Commodore listing showed Beige, Black, Transparent Red, and Transparent Clear choices but was out of stock on 2026-07-27. The seller explicitly documents C64 Ultimate use but does not enumerate original C64 or other 9-pin systems, so no broader compatibility is inferred.

Replaces one SID socket with two or three emulated SIDs, or combines SID emulation with SFX Sound Expander-compatible FM synthesis.

The official store showed four ARM2SID variants in stock on 2026-07-28, priced from EUR 53 to EUR 58. Choose the cable, optional second socket, and host-specific version carefully. Additional SID and FM modes require the documented chip-select and audio connections; the optional second socket does not carry EXT IN.

Microcontroller-based plug-in replacement for a C64 or C128 6581 or 8580 SID with software configuration, updateable firmware, and analog control inputs.

The official Retrocomp product page showed more than 10 ARMSID v1f units in stock at EUR 34 on 2026-07-28.

Lets a 1088XLD emulate a joystick with its PS/2 keyboard arrow and trigger keys.

The project publishes schematics, Gerbers for both required boards, a bill of materials, and TK-II 2.7J firmware. A complete installation needs the piggyback board, interface board, ribbon cable, and programmed keyboard-controller firmware. The three auxiliary outputs are momentary open-collector signals and may need latches for some uses.

Single 16 MB, 60 ns, non-parity fast-page-mode SIMM for specifically listed 30-pin Macintosh systems.

The Artmix product page reported out of stock on 2026-07-24. Check the direct page for a restock and confirm the exact computer's ROM, addressing, bank-population, and clearance requirements.

Replaces the Atari 800 personality module with selectable operating systems, faster floating-point code, and configurable extra memory.

The page reported four boards in stock on 2026-07-27. Functions that use $C000-$CFFF are mutually exclusive, so Omnimon and 128 KB Mosaic memory cannot be enabled together. Axlon cards require RAMROM's onboard RAM to be disabled. The optional DS1210 backup controller and coin cell are user-supplied; the seller page inconsistently calls that cell CR2032 and CR2023, so verify the fitted holder before buying a battery.

Adapts the Pixels Past 8K or 16K EPROM cartridge into an eight-selection homebrew multicart for the Atari 800XL.

Human review found the combined visual material sufficient for a skilled builder. It remains an adaptation rather than a revised fabrication package: the linked Gerbers and assembly material are for the unmodified Pixels Past single-cartridge PCB, while the eight-way changes appear only in an inline diagram with no separate revised Gerbers, bill of materials, ROM-preparation guide, or textual selection instructions. Pixels Past licenses its base files under CC BY 4.0, but no license for the eight-way modification was verified.

Breaks compatible Atari and Commodore monitor-port signals out to S-video, composite video, and bridged mono audio connectors.

The current product data and catalog reported the assembled breakout in stock on 2026-07-27. Cables and any required computer modification are not documented as included.

Selects between two programmed Atari operating-system ROM banks according to the Reset key state at power-on.

Lotharek's version 2 page exposed a login-or-register-to-buy path on 2026-07-27. It arrives flashed with Atari OS and QMEG 4.04, and a small onboard switch selects the default bank. A socketed OS ROM makes installation simple; otherwise the original ROM must be desoldered and a socket should be fitted. The page markets the device for Atari 8-bit computers but illustrates only an 800XL connection, so broader target relationships remain withheld. Do not use it with Ultimate 1MB.

Adds a battery-backed real-time clock to Atari XL and XE computers as an internal module, pass-through cartridge, or circuit inside another cartridge.

The project page publishes a parts list, clock and address-decoder schematics, battery and rechargeable-cell backup circuits, and an ARC handler archive. It recommends internal installation because the pass-through and inside-another-cartridge forms may cause more problems. The page does not provide a step-by-step bus-wiring guide: an internal build must source D0-D3, A0-A7, R/W, phase 2, power, and D5xx cartridge-control signals, while a cartridge build uses the cartridge connector. No explicit project license or current assembled seller was verified.

Period SIO floppy drive adds double-sided, double-density 5.25-inch storage and faster double-density transfers to Atari 8-bit computers.

Find a complete used drive with the correct AC adapter and SIO cable. The bundled DOS 2.5 supports single and enhanced density but not the XF551's full double-sided, double-density capacity; use DOS XE or compatible third-party software for that mode. Most drives use a Mitsumi mechanism with a rectangular activity LED, while later Chinon examples have a round LED and stricter flippy-disk limitations. The 300 RPM mechanism can also conflict with a small amount of speed-sensitive copy protection.

Provides blank flash cartridges and a USB programmer for building reusable Atari 8-bit multicarts.

The official page showed the cartridges and USB programmer in stock on 2026-07-25. These are blank programmable products and do not include commercial ROM images. Unplug the programmer before attaching a cartridge, verify label-side-up orientation, and connect directly to the PC rather than through a USB hub for first-time use. Backwards insertion can damage both the cartridge and programmer.

Adds CompactFlash storage, cartridge-image loading, and onboard flash and SRAM to Atari XL and XE computers.

The official page showed MyIDE-II cartridges and accessories available on 2026-07-25. A prepared CompactFlash card is offered separately, so confirm the selected package contents. No ROM images are included; users must supply legal images and software.

Connects Atari 8-bit SIO computers and disk drives to a modern host for peripheral emulation and disk transfer.

The official page showed USB and RS-232 ordering options on 2026-07-25. Select the interface and connector arrangement for the intended host software and SIO chain. An Atari SIO cable and the computer or disk-drive hardware needed by the chosen workflow are not included. The USB setup documentation is dated and lists Windows 95 through Windows 7, so confirm current host support rather than assuming modern Windows compatibility.

Adds a two-port USB host interface for supported keyboards, controllers, mice, and other driver-backed devices.

Atarimax marked the cartridge in stock and ready for shipment on 2026-07-25, although the same page called the current price a preorder promotion through 2026-07-31. This is not a generic plug-and-play USB port: support depends on Atari-side drivers. Atarimax still describes the software as early beta, and the MicroUSB project's substantive status notes are historical, so check the device matrix and exact driver before buying hardware for a particular peripheral.

Adapts a modern 24-pin ATX power supply to selected Power Macintosh G3 and PCI Graphics G4 towers.

The current product page listed the cable without an out-of-stock marker on 2026-07-24. No ATX power supply or other conversion hardware is included.

Adapts a modern ATX power supply to a Power Macintosh 8600 or 9600 without cutting the computer's chassis.

The current store listed the conversion kit without an out-of-stock marker on 2026-07-24. The ATX supply and tools are not included.

Adapts a modern ATX power supply to an IBM XT and recreates the missing -5 V rail.

Retro Electronics listed one board in stock on 2026-07-25. The board does not include an AT P8/P9 connector or its cables; the buyer must supply and solder them.

A family of SD multicarts for Atari 8-bit computers, ranging from cartridge loading to disk, tape, memory, clock, and audio expansion.

All three product pages showed In stock and Add to cart on 2026-07-24. Optional SIO, ECI, PBI, and DAC cables are separate. SUBCART's extra functions need ECI or PBI, and the maker does not recommend them on a machine with U1MB or another third-party internal memory expansion.

FPGA-based AY-3-8912 replacement with the original Amstrad sound path and an optional separate three-channel stereo output.

The Lotharek page exposed a login-or-register-to-buy path, and Retro Lemon showed the module in stock on 2026-07-28. Retro Lemon identifies it as an AY-3-8912 replacement that auto-detects Amstrad or ZX operation and says normal installation is a no-solder socket swap. Optional CPC 6128 stereo output still requires removing or cutting resistors R117 through R120 and wiring AL and AR or a separate jack. Exact ZX models, other chip footprints, orientation, voltage, clock, and firmware remain undocumented, so no ZX target is attached.

Adds an internal AY or Yamaha sound generator and stereo output to a ZX Spectrum through a CPU adapter.

Lotharek marks the interface discontinued. The AY chip and audio connector are not included. Plug-in installation assumes a socketed CPU; otherwise safe CPU desoldering and socket work are required. Preserve pin-1 orientation at the CPU adapter, ribbon cable, and sound-chip board, then provide the documented stereo and ULA-audio wiring.

Small C64 prototyping boards for the cartridge port, user port, or a combined dual-port project.

The email-order page was last updated on 2025-01-01 and then said any combination was available, but it publishes no price, checkout path, schematic, pin map, bill of materials, design files, or protection details. Confirm present stock, the exact board variant, connector and header parts, case fit, and documentation before ordering. Treat every exposed power and signal line as unprotected unless the seller supplies contrary electrical documentation.

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

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.

Programs 16K, 32K, 64K, and 128K EPROMs from an Apple II expansion slot.

The kit was out of stock on 2026-07-24. It is a tall card and requires soldering; verify physical clearance, software, and the exact EPROM type before use.

VIC-II socket video coprocessor that adds programmable display effects, 512 KB of local memory, and integrated video cleanup to a C64.

The official project page remains online, but its Buy now area exposed no price, stock state, or working order destination on 2026-07-30. The last seller route found during this pass returned 404, and human review found no replacement seller, so confirm a current source before planning a purchase. BeamRacer also includes Lumafix Pro, software control of the HMOS-II gray-dot effect, a direct VideoMod connection, USB-C firmware updates, and the optional VBASIC development environment. Some narrow C64C boards may require a nearby capacitor to be resoldered for case clearance.

Recreates the Gravis Ultrasound PnP ISA sound card around an AMD InterWave chip, with an optional IDE CD-ROM interface.

The maker has not fabricated or tested this board and has not generated a fabrication package. It also requires an AMD AM78C201 InterWave chip. Treat it as an experimental design and build at your own risk.

Combines DivMMC-compatible microSD storage, 512 KB of expansion RAM, dual-AY audio, DAC modes, and configurable joystick or mouse input on the ZX expansion bus.

The seller exposed a login-or-register-to-buy path on 2026-07-27 and documented firmware 1.5. Power off before changing the edge connection or input mode. Automatic Sinclair-versus-Amstrad selection depends on 9 V at edge pin 3B; compatible clones without that signal need the documented modification. Firmware updates require a separate Gowin programmer and removal of the flash ROM. Prepare a separate FAT32 microSD card with the supported ESXDOS release.

Converts Commodore 128 80-column RGBI into 15 kHz analog RGB for a compatible display or a separate VGA scaler.

The official site says sales resumed through its Square store in January 2024, but current stock was not independently confirmed on 2026-07-30. BIT-C-128 is not a scan converter: direct use requires a display that accepts roughly 15.75 kHz analog RGB. An ordinary VGA display also needs a GBS-8200, GBS-8220, or another suitable scaler. Supply regulated 5 V power and the cables or adapters required by the selected display path.

A newly made real-time-clock and nonvolatile-memory module for the Atari Falcon030.

The product page exposed a login-or-register-to-buy path on 2026-07-27, but it provides only the product name, Falcon purpose, designer, price, and photographs. Human review found no further technical detail. Treat this as evidence that an RTC/NVRAM module is available, not as installation guidance; ask the seller about the replaced component, backup design, setup, and motherboard support before purchase.

Visualizes Macintosh PDS signals with LEDs and provides a pass-through plus a right-angle test connector.

The Juicy Crumb page showed BlinkenPDS in stock on 2026-07-24. It is a bench development tool and is not intended for permanent in-case use; the maker says it fits poorly inside a computer. The second connector does not establish that arbitrary pairs of PDS cards are electrically compatible.

Recreates the Apple II Lego TC Logo interface card for controlling Lego Technic machines.

JCM showed 25 cards in stock on 2026-07-24. A working setup also requires a Lego 9750 Interface A with its IDC-20 cable and 9 V power supply, at least one compatible 4.5 V motor, and suitable Lego Technic parts.

Open hardware SCSI emulator with SD-backed storage, optional Wi-Fi networking, and host-side management tools.

Current seller checks on 2026-07-27 found a $39 internal 50-pin Pico 2 W kit, a $49 assembled external DB-25 model, a $49 PowerBook model, and a $59 assembled Ultra Narrow 50-pin model at authorized seller ToTs RETRO. JCM also carried assembled Ultra hardware and model-specific Macintosh adapters. Prices, stock, included media, and support differ by seller. Ultra models require Berg or Molex power and cannot run from SCSI termination power. The initial Ultra hardware release is not yet open hardware, although its firmware remains GPL; the project says hardware licensing will open later.

Packages a Raspberry Pi 3B+ and RP2040 keyboard interface into an original C64 or C64C case as a low-latency BMC64 system.

Current shortboard and longboard v4.0 files and an easier-to-assemble v4.0.1A variant were available on 2026-07-27. No assembled seller was verified. A complete build needs both PCBs, components, assembly, a Raspberry Pi 3B+, Waveshare RP2040-Zero, microSD card, original C64 or Mechboard64 keyboard, suitable case, and power. BMC64 itself is not compatible with Raspberry Pi 4B or 5.

Adds 1 MB of banked RAM to an Atari 1200XL or 800XL with a 30-pin SIMM and custom refresh and bank-selection logic.

The archived article provides the circuit discussion, 1200XL connection table, SIMM pinout, and software notes but describes the 800XL only as having similar connection points. It is an advanced historical wire-and-perfboard build. The author reports that the SpartaDOS cartridge does not function with this configuration and that ordinary SpartaDOS and much commercial software see only a 320XE-style subset; MYDOS 4.5.1M or newer needs the documented page sequence.

Runs a 68030 CPU and optional 68882 FPU at 47 MHz in SE/30 and socketed modular Macintosh configurations.

Juicy Crumb showed a $309 to $359 Add to cart path for Booster 2.0 on 2026-07-27. Choose the exact PDS or PGA-socket variant for the host. Booster 1.x is superseded but its original-card schematic and GAL archive remain available. PDS-card compatibility differs between generations, and System 7.5 or later can produce sound glitches on 1.x cards.

Cartridge-port prototyping board with a mini breadboard and jumper leads for building C64 circuits.

Poly.play listed SKU PP0057 at EUR 17 including German VAT but marked it out of stock on 2026-07-30. The page publishes no schematic, pin map, design files, license, buffering, isolation, fusing, current limit, or power-handling specification. Confirm a restock and treat every computer signal and power line as unprotected.

Provides a daisy-chainable SmartPort hard disk backed by one to four ProDOS images on microSD.

Joe's Computer Museum showed 33 assembled DominoDisk units in stock on 2026-07-24. The Mini BurgerDisk page also exposes an assembled selector, while the public project supplies firmware, PCB, schematic, and enclosure files for a DIY build. Follow Apple's device-order rules in a daisy chain; a Liron card cannot drive a 5.25-inch drive.

Provides a weighted, tabletop arcade joystick for Atari 7800 and Atari VCS-style computer control ports.

BX Foundry's joystick production run concluded in mid-2019. The maker archive remains available, but it provides no current order route or public construction files. Search the used market for an original unit.

Historical C64 user-port board providing 32 general-purpose input and output connections.

A February 2021 demonstration points to former eBay item 333905309830, but the exact listing failed two Tavily extractions after the required 60-second retry and is logged as WF-065. No current hardware seller, board design package, manual, pin map, electrical limit, protection circuit, or hardware license was verified. Treat the board as a used-market find. The demonstrated LED bank uses 1K resistors and leaves VCC disconnected; that example is not a general electrical specification.

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

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.

Combines the Commodore 128's separate 40-column analog and 80-column RGBI outputs into a switch-selectable SCART connection.

Retro-Updates marked revision 5.1 sold out and soon available again on 2026-07-30. The official project page still describes direct email ordering at an older EUR 22 price, but its order news is from 2021; confirm current production, price, revision, case choice, and shipping before paying. This adapter does not scan-convert the original video timing. A SCART display must accept the signals directly, or a separate SCART-to-HDMI converter is required and may produce variable results.

Converts the C128's 80-column digital RGBI output to analog RGB and composite sync for a separate video scaler.

Protovision reported eight units in stock at EUR 30 on 2026-07-30. This adapter converts signal levels and combines sync but does not raise the scan rate. Its documented setup uses a separate GBS-8200 or GBS-8220, which is not included. Follow the page's normal/inverted-sync procedure if GBS auto scan does not lock cleanly.

A passive buildable adapter that converts C128 80-column RGBI to 15 kHz analog RGB and adds monochrome composite output.

The repository publishes KiCad schematic and board files plus Gerbers. This is not a scan doubler or scaler, so the connected display must accept 15 kHz analog RGB with separate 5 V horizontal and vertical sync. The design has no CGA brown fix, does not provide VGA identification or communication signals, and will not work with a downstream converter that requires composite sync. The maker reports a successful Dell 27-inch monitor test but calls the test computer a 'C128cr'; do not infer separate C128D or C128DCR testing from that ambiguous label.

Socketed daughterboard that expands the C128 or plastic C128D from 16 KB to 64 KB of VDC video memory.

The maker's store exposed an active order path and reported stock on 2026-07-30. Installation requires removing the original metal heatsink and carefully extracting and reinstalling the MOS 8563 with the correct orientation. The maker recommends a modern low-profile heatsink because the daughterboard raises the chip. Reaching the VDC in some C128D systems may require removing the power supply, floppy drive, and drive controller.

Combines a Commodore 128's 40-column and 80-column video paths in one switchable external adapter.

Pyrofer's Projects lists the NTSC board and its separate C128DCR mounting tab as out of stock. The normal package uses tabs for the flat C128 and standard C128D; the differently spaced C128DCR requires the separate tab. Although the board has a PAL/NTSC selection, the seller says changing format also requires a different oscillator IC, and the listed package includes the NTSC oscillator.

Adds a buffered external C128D keyboard connection to a Commodore 64 while retaining the original keyboard.

The surviving workshop page provides a schematic, pin map, parts list, and verified build instructions, but no PCB files, kit, or explicit reuse license. It warns that a direct long-cable connection can overload and destroy the C64 CIA. The buffered design was intended for cables as long as 10 meters, although its troubleshooting section still recommends shortening a troublesome cable to about one meter.

Lets a detachable Commodore 128D keyboard serve as the keyboard for a Commodore 64.

Protovision listed 17 units from EUR 15 with a one- to two-week shipping estimate on 2026-07-30. Its news page says versions are available with or without an extension cable. Human review found no visible active components or additional documentation, but that does not prove the board is unbuffered. Ask the seller about buffering and safe cable length before using a long cable, and connect or disconnect the adapter only while the computer is powered off.

Tested 64K-by-1 4164 DRAM chips for repairing Commodore 64 motherboards that use the eight-chip, 16-pin memory layout.

Both exact product routes were present on 2026-07-30, but Tavily did not expose an unambiguous current cart or stock control on the ToTs RETRO page, and Retroleum was temporarily closed until approximately the beginning of August 2026. Confirm stock before ordering. Match the installed memory organization and motherboard rather than relying on case style: Retroleum explicitly excludes Assy 250466 and C64C boards that use two 41464 or 4464 devices.

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

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.

Generates configurable YPbPr or RGB from VIC-II bus activity with an FPGA while retaining improved composite and S-Video output.

VideoGamePerfection's EUR 60.00 kit was out of stock on 2026-07-27, but the complete open design remains buildable and upstream firmware 2.12 was released on 2026-07-03. This is a substantial soldering installation, and the original RF output is removed.

Open, through-hole RF-modulator replacement with adjustable C64 luma and chroma output levels.

The repository supplies KiCad sources, Gerbers, a schematic, a BOM, and assembly and adjustment instructions. Components were estimated at about $12 when documented, excluding PCBs and shipping. Building the board requires through-hole assembly; installing it requires safely desoldering the original RF can and selecting the correct jumper configuration. Using the shortboard setting on a longboard can feed the wrong voltage and damage the VIC-II.

Adds an inexpensive battery-backed real-time clock to a Commodore 64 through the user or cassette port.

The current project page provides version 1.0 software and exact wiring for three C64 connection choices. Gregory Nacu's i2c6502 source independently documents the C64 user-port PB2/PB3 implementation and DS3231 example under the MIT license. A generic RTC module, connector or pass-through board, wire, and battery are separate. Many inexpensive modules include a charging circuit intended for a rechargeable cell; follow the project's component-removal instructions before substituting a CR2032 or CR1225 primary cell. The Timo Voutilainen package does not state a hardware fabrication or software license.

Provides an open build for selecting either Commodore 64 control port from one Atari-style joystick, with optional second-fire and autofire circuits.

The repository supplies KiCad files, Gerbers, a schematic, bill of materials, and assembly guidance. Inspect the completed board for solder bridges and support it while pressing its buttons. Never move jumpers while powered or map two physical inputs to the same function. Do not connect a Sega Genesis or Mega Drive controller; the maker warns that it may damage the C64 and directs those controllers to the separate Mega Switcher.

Swaps both Commodore 64 control ports and adds a PS/2 mouse input compatible with 1351-aware software.

Sordan exposed a current Buy now control and says stocked items are ready to ship. The package includes a white 3D-printed case. The seller explicitly supports paddle controllers and says the circuit protects against static while controllers are changed, but does not publish a schematic, supported PS/2 protocol variants, USB-mouse compatibility, connector pinout, or hot-plug procedure.

Turns as many as two Atari-style digital joysticks or four paddles into USB input devices for a modern computer.

The repository supplies board fabrication files, a schematic, Arduino firmware, a bill of materials, and assembly guidance. A build needs an Arduino Pro Micro and the components selected for either the Atari-style or Sega configuration. Paddle mode is a JoyConverter firmware option selected while powering the adapter.

Rebuilds a Commodore 64 around a preassembled replacement motherboard with automatic chip configuration, static RAM, flash ROM, and dual-SID support.

Individual Computers marked the board available for immediate delivery on 2026-07-27. It is not a complete computer: the key CPU, port, sound, and video chips are not included. The product page still uses some preproduction or older photographs, so physical appearance can differ.

Replaces the paired 41464 or 4464 DRAMs on later two-chip C64 boards with a modern SRAM module.

Jaystonian showed nine assembled modules in stock at USD 14.99 on 2026-07-29, and Retro Lemon exposed a GBP 17.50 product page without an out-of-stock marker. Assy 250469 is the well-tested target. Jaystonian reports mixed results on 250466, and the open project's author had only tested 250469. Original soldered DRAMs require careful desoldering and sockets before this becomes a plug-in repair.

Passive one-to-three Commodore 64 user-port expander with an onboard reset button.

The Arcadia by Eye-Box listing was out of stock on 2026-07-27. A reviewed Shareware Plus unit exposed three connectors. The right-hand position can obstruct the cassette port, and the passive board has no per-slot disable controls. Connect or remove peripherals only with power off.

Adds a Yamaha V9958 or V9938 video processor, 128 KB of dedicated VRAM, RGB output, sprites, and enhanced graphics modes through the expansion port.

The project publishes the final 1.0 PCB, schematic, Gerbers, GAL files, documentation, and demonstration software, but no current assembled seller was verified. A build requires a V9958 or modified V9938 configuration, two compatible DRAM devices for 128 KB of interleaved VRAM, programmable logic, an EPROM or EEPROM if desired, and substantial surface-mount assembly.

Open RF-modulator replacement that improves the C64's original luma, chroma, and composite video signals.

Retro Electronics listed one board in stock on 2026-07-25. Installation is an irreversible soldering job that removes the original RF modulator, adds two headers, and solders a ground wire.

Buildable NodeMCU Wi-Fi modem for the Commodore 64 user port with voltage level shifting and status indicators.

The complete project remains downloadable. Retro-Updates listed an assembled revision-2 version for the C64 and C128, but it was out of stock on 2026-07-30. Revision 1 fits only the smaller WeMos NodeMCU v3 form factor; revision 2 supports both common board widths.

Passive adapter-cable options for powering a Commodore 128 from a suitable modern C64 power supply.

On 2026-07-30, CMD Marketplace listed its 15 cm adapter at USD 19 with five units remaining, Electroware listed its 16 cm adapter at EUR 15.99 with dispatch in three to five days, and Keelog listed its 22 cm adapter at USD 23.99 or EUR 20.99. Commodore4ever listed its 90-degree option at USD 14.99, but the page did not expose unambiguous variant stock. CMD Marketplace requires a new switching C64 supply capable of at least 3 A and explicitly warns against using an old original C64 supply. Treat that as a minimum for its adapter and confirm the requirements of any other adapter and supply combination before use.

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

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.

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.

A compact universal-input replacement supply for Commodore 1541-II and 1581 floppy drives.

Retro Lemon exposed a live GBP 27.50 listing with free delivery on 2026-07-30, but the extracted page did not expose an unambiguous stock or Add to Cart state. Confirm availability and delivery region before ordering. The page does not publish over-voltage protection, fusing, isolation, connector pinout, or serviceability details.

Adds Hayes-style Wi-Fi modem access and ZiModem networking functions to a Commodore 64 through the user port.

The maker page exposed current eBay and Amiga on the Lake purchase routes on 2026-07-30. The buyer's-guide card and cased listings are one hardware family; confirm the enclosure, board revision, and installed firmware with the seller before ordering.

Brings the Commodore 64 Ultimate's internal user-port header to an edge connector for user-port peripherals.

The direct Commodore listing was out of stock on 2026-07-27. The connecting cable is included. The seller documents this only for the Commodore 64 Ultimate, whose user-port header is internal; an original C64 already has an external user-port edge connector and does not need this adapter.

Swaps a Commodore computer's two control ports while preserving both digital joystick and analog mouse or paddle signals.

The surviving AmiBay production runs are closed sales archives. COREi64's former product route is currently replaced by a store-wide notice saying the shop will return in Fall 2026, so no current C8D order path is verified. The original C8D maker site also failed Tavily extraction twice after the required retry and is recorded as WF-050.

Single-position angled C64 cartridge adapter with power switching, reset, an activity LED, and support feet.

The black, red, and white variants were all out of stock on 2026-07-27. Color variants are one hardware family. This adds convenience rather than another simultaneous cartridge position; power off the computer before connecting or removing either board.

Adds SD-card PRG and TAP loading, a fast loader, Wi-Fi file transfer, and cross-development tools through the cassette port of several Commodore 8-bit families.

The maker states that Cassiopei v2.0 is not available. The hardware is described as functionally complete, while firmware, software, manuals, and downloadable updates remain published.

Turns a spare compact-Mac logic board into a small desktop computer with modern power, display, and storage hardware.

On 2026-07-24 JCM showed 5 printed 128K/512K cases, 3 Plus cases, 2 SE/SE30 cases, and 5 Classic/Classic II cases in stock. This is an enclosure, not a complete computer: supply a working logic board, power and video electronics, storage, input devices, display, cabling, and other desired parts. GutBomb's printable design is CC BY-NC-SA and does not cover the separate electronics.

Current hand-built replacement for the MOS 8701 clock generator in later PAL and NTSC Commodore 64 boards.

CBMretro exposed an in-stock add-to-cart path on 2026-07-30. The page says only that the board is for later C64 models and does not name assembly numbers or the C128. Confirm that the computer actually uses a socketed MOS 8701 and verify orientation before ordering or installation.

Adds a driverless 32 MHz 68030 accelerator to a Macintosh Color Classic or LC II processor-direct slot.

The current product page explicitly said Out of Stock on 2026-07-24. Its mid-February 2025 next-batch note is stale.

Adds CompactFlash storage to an Apple-1 or a compatible clone.

ReActiveMicro showed the CFFA1 in stock with backordering enabled on 2026-07-27. The supplied package includes a CompactFlash card and software. It does not work in Apple II systems.

Adds CompactFlash and USB mass storage plus floppy-image mounting to slotted Apple II and Apple III computers.

ReActiveMicro showed an in-stock, backorderable Add to cart path on 2026-07-24. The included media is preconfigured, but user-supplied images and operating systems still need to be compatible with the selected computer.

Adds two joystick ports to a compatible Commodore user port for four-player games that support the CGA adapter protocol.

Protovision showed 17 individual Computers adapters in stock at EUR 25 with a one- to two-week shipping estimate on 2026-07-30. CBMretro also exposed an add-to-cart route for Pasi Lassila's enhanced Neat design at EUR 26.90, and ZGCS showed two assembled compatible boards at USD 22 on Tindie. Install or remove the adapter only with power off and observe connector orientation. Do not connect it to a Plus/4: individual Computers warns that doing so risks damage. The PET 2001 user ports lack the required power connection, and the maker discourages modifying a historic machine to add it.

Converts digital RGBI into 15 kHz analog RGB and can break out a Commodore 128's 40-column S-Video and audio.

The maker lists the assembled board as out of stock and publishes no fabrication package. This is not a scan converter; the display must accept the source timing, normally about 15 kHz, or use a separate scaler. The maker's design history says the completed logic omits the valid intensity-only dark-gray color, which appears black. The board also passes 5 V to HD-15 pin 9; verify that the attached cable and display do not ground that pin.

Converts MDA, CGA, EGA, and Commodore 128 RGBI into 15 kHz analog RGB with selectable sync.

The maker labels the current project revision released, but its assembled Tindie listing said the seller was taking a break on 2026-07-30. The maker publishes a schematic but not a complete fabrication package. This is not a scan converter: an ordinary VGA display needs a GBS-8200, GBS-8220, OSSC, or another compatible scaler. The board requires 5 V through Micro-USB or a suitable GBS power connection.

Adds bootable RomWBW storage and FAT32 file exchange on USB flash drives to supported RC2014 configurations.

RomWBW 3.4.0 or later is required. The project recommends newer branded USB sticks of at least 1 GB because some older, smaller, or unbranded media are unreliable.

Adds an internal SCSI connection and termination power to a Macintosh Plus by clipping over its SCSI controller chip.

The JCM page showed 18 units in stock on 2026-07-24. Installation requires opening the compact Macintosh, removing and reinstalling its logic board, routing a SCSI cable through a tight chassis gap, and supplying a separate SCSI device.

Adds a battery-backed DS3231 clock, external LED time display, date display, and timer to a Commodore 64.

The Tindie page listed Clockwork64 at USD 38 but had ordering paused while the seller takes a break through July 31, 2026. It calls this the final batch before retirement, so confirm that an order can still be placed after the seller returns. A CR2032 is included. The maker reports compatibility problems with modern J-CIA replacement chips and directs buyers to version 0.2 of Timo Voutilainen's RTC software.

Licensed, made-to-order recreation of the CMD hard drive with BlueSCSI v2 and externally accessible SD storage.

ToTs RETRO exposed an Add to Cart path at USD 899.99 on 2026-07-27. Each drive is made to order with an advertised lead time of up to one week. Supply an IEC serial cable and a compatible 1581 or 1541-II power supply; neither is included. The seller has not tested simultaneous tape-drive use.

Current switched cable variants for using the C128's 40-column analog video and 80-column RGBI output with one display setup.

Both Tindie pages exposed current prices and ordering controls on 2026-07-30; the premium version explicitly reported three units left. Shipping depends on the selected destination, and no rate was shown during extraction. The seller documents a shielded cable, an onboard micro PCB, and an operating LED. No scan conversion is documented, so confirm that the intended display accepts the cable's original-timing composite, S-Video, and SCART RGB signals.

Provides an RCA color-composite output from the Apple III family's 15-pin color-video connector.

JCM showed 14 units in stock on 2026-07-24. A PAL Apple III still produces monochrome video through this adapter; Colorizer 3 does not convert PAL timing to NTSC color. JCM recommends the separate Phase 3 modification for more accurate NTSC color.

Adds 10/100BASE-T Ethernet to Macintosh systems through the PCI-derived Comm Slot II interface.

The JCM page offered the card through an Add to cart control on 2026-07-24. It was tested on a Performa 6400/180 with Mac OS 7.6, 8.1, 8.6, and 9.1. Other Comm Slot II systems are an interface-level relationship, not a claim of model-by-model testing.

A simple buildable RGBI-to-analog-RGB adapter for 15 kHz-capable displays with a VGA connector.

The PCBWay project supplies a shared board-order path and a short component list. Assembly is required. This is explicitly not a scan doubler, so most ordinary VGA displays will not work; verify that the exact monitor accepts 15 kHz analog RGB. The maker reports a successful test with a flat Commodore 128 and an Acer G206HQL, but does not separately document C128D or C128DCR testing.

External displays for checking the 5 VDC and 9 VAC outputs of Commodore power supplies, with the MkII adding current measurement under load.

The exact review was published in March 2020 and a February 2023 comment says the seller was still making the monitors. The review describes an unofficial Commodore-styled product made by an unnamed Australian builder, not a verified Commodore-manufactured accessory. A current-looking Pocket 1501 eBay route failed exact Tavily extraction and failed again after the required 60-second retry under WF-068, so its maker, stock, price, package, and relationship to MkI and MkII remain unverified. The separate FDD II drive-supply monitor is not folded into this host-monitor family. This device displays readings; no automatic cutoff, regulation, over-voltage clamp, fuse, or other protective action was verified.

6522 VIA interposer that changes a Commodore 1541 drive between device IDs 8 through 11 without cutting its original jumpers.

TheRetroChannel listed five boards in stock on Lectronz on 2026-07-27. External wiring and DIP switches are not included. A drive with a soldered 6522 first needs the chip desoldered and a socket installed; an external switch may require case cutting.

Connects a standard 3.5-inch PC floppy mechanism to a Commodore 1581 disk drive.

Retro Electronics listed two adapters in stock on 2026-07-25. Only the adapter is supplied; cables and the replacement floppy mechanism are not included.

Assembled replica controller board for building a Commodore 1581-compatible 3.5-inch disk drive.

Retro Electronics listed the fully assembled and tested board out of stock on 2026-07-25. Only the controller PCB is supplied.

Upgrades an original Commodore 1764 REU from 256 KB to 512 KB and supplies parts that can also repair or expand other 17xx REUs.

The current Shopify product page exposed a priced checkout product on 2026-07-29. This is a component kit for an original REU, not a complete memory cartridge. The page does not provide a complete board-revision-specific installation procedure; use appropriate Commodore service information, ESD precautions, and an experienced installer.

Replaces a missing or failed Commodore power indicator with a prewired round or rectangular LED assembly selected for the case and motherboard layout.

AMI64 listed its red breadbin and C64C choices for GBP 4.95 on 2026-07-30. Poly.play also maintained separate current short and long C64C and breadbin product routes. Retroleum listed original and new round and rectangular assemblies but was temporarily closed until approximately the beginning of August 2026. Color is cosmetic, but LED shape and cable length are not: choose them for the exact case and board position. Confirm current stock before ordering.

Recreates a C64 as a complete FPGA-based keyboard computer with original peripheral interfaces plus HDMI, USB, microSD, Ethernet, and Wi-Fi.

On 2026-07-27, the breadbin BASIC Beige model exposed a Buy Now path and regional stock, while the slimline Commodore 64C Ultimate was a paid preorder scheduled for factory dispatch on September 15, 2026. The internal microSD card is sold separately. The externally accessible user port requires a separate adapter. Commodore warns that Ultimate64 and C64 Ultimate hardware and firmware are diverging; unsupported firmware can leave a machine nonfunctional and resulting damage is outside free support, warranty service, and replacement.

A period automatic RF switch box currently offered as new old stock for Commodore 64 and 128 systems.

Poly.play listed original part number 252652-01 as immediately available in original packaging on 2026-07-30. This is finite new old stock, not a modern video converter. It requires a television or demodulator with a compatible analog RF input, connector, channel, and regional broadcast standard; the seller page does not publish those electrical details.

Connects one CS/A65 expansion card to a Commodore 64 expansion port or beneath a PET's socketed 6502.

The C64 revision 1.0C is marked okay and publishes Eagle files, but it works only with the C64, not the C128, and a fitted CS/A card can conflict with long video or IEC plugs. For PETs, revision 1.1A was tested only in a CBM 8296 and had power and clearance problems. Later 1.2A and 1.2B layouts add 3.3 V power and more mounting options but are explicitly untested. A working 8296 Ethernet stack is documented. usb65 later lists PET plus adapter plus NetUSB 1.x as tested, although the older NetUSB page says its single PET-adapter test was not fully working and suspected a supply problem. Treat that USB path as experimental. No current assembled seller was verified.

Current C64 and C128 user- and cartridge-port boards that expose labeled pins for prototyping and hardware development.

Commodore4ever exposes current priced product variants for separate C64/128 user-port and cartridge or expansion-port boards. The user-port page documents its labeled male header and intended test uses. The expansion-board title and board label say EPB and cartridge or expansion port, but its body mistakenly describes access to the User Port and does not enumerate its signals. Human inspection found these guide breakouts to be basic passive pin extenders with no visible active components. No buffering, isolation, fusing, or current limiting is documented; exposed computer pins should not be treated as protected. Syzygy's C64 user-port version is retired and needs its selected header rows soldered.

Period cartridge interfaces connect a C64 or VIC-20 to PET-style parallel disk drives, printers, modems, and other IEEE-488 equipment.

These are original period interfaces to find used or reconstruct from archives, not current products. Match the cartridge to the exact computer and verify its ROM. The original C64 software occupies part of the $C000 area and disables serial IEC; Andre Fachat's separate modified C64 KERNAL can retain both buses, but it is not part of the cartridge.

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

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.

Adds experimental USB host and device hardware through Commodore user and cassette ports.

Revision 1.0A is marked okay but was tested only on a PET. Revision 1.1A adds separately regulated, switchable USB host power but is explicitly untested. The interface uses both the user port and cassette port; PET ROM interrupt handling can switch cassette-motor-controlled USB power off unless software works around it. usb65 describes preliminary keyboard mapping, limited features, broken MAX3421 hub enumeration, and only partly working device mode. USB mass storage and networking are future plans, not supported features.

Host-specific passive A/V adapters for the VIC-20, C128 family, Plus/4, and Ultimate64 replacement mainboards.

Commodore4ever exposed active Add to cart controls for all four variants on 2026-07-30. The Ultimate64 board uses a different A/V pinout from an original C64; do not use that adapter on a stock C64 or assume compatibility with the newer Commodore 64 Ultimate. The C128 variant handles the 40-column analog output, not the separate 80-column RGBI port.

Protected switched-mode replacement supplies for the C64 and round-connector VIC-20CR, with separate adapters for the C128 and Plus/4.

On 2026-07-30, Commodore4ever listed the original ATOM and ATOM v2.5 at USD 59.99 and ATOM RETRO at USD 69.99; all three were sold out. The official Plus/4 adapter was also sold out at USD 24.99. A separate live 90-degree adapter page listed a 64-to-128 option at USD 14.99, but did not expose unambiguous variant stock or identify every supported ATOM revision. The original ATOM page lists separate North American 120 VAC and European 230 VAC configurations, ATOM v2.5 lists only the North American input, and ATOM RETRO says its European version is currently unavailable. Surviving pages provide too little detail to establish exact specifications or final availability for the older PS-64 with LED and PS-64/128. Do not assume that ATOM specifications apply to those predecessor models.

User-port Wi-Fi modem for reaching Telnet BBS services from several Commodore 8-bit computers.

The seller's collection listed the modem as sold out on 2026-07-30. An optional case is an accessory for the same modem family. The product page does not provide a public firmware or complete hardware build package.

Adds solid-state CompactFlash storage for CP/M or RomWBW configurations.

The fine-pitch CompactFlash socket can be supplied loose with an optional stencil or pre-soldered and tested. Standard RC2014 BASIC cannot access this storage. CP/M requires the documented Pageable ROM and 64K RAM configuration, while RomWBW uses a 512K ROM 512K RAM setup.

Replaces missing or broken case-mounted programmer's switches on compact Macintosh computers.

Both product pages said Sold out or Out of Stock on 2026-07-27. The Greeny-switch resin can break if excessive force is applied. Choose the model-specific variant; neither seller establishes cross-family interchangeability between the early compact-Mac and SE-family switch assemblies.

Open replacement battery module for the Compaq Portable III using a CR2477N coin cell.

This is a self-assembly project rather than a retail product. Follow the documented cell polarity and solder the pin headers in the specified upside-down orientation.

Provides a new-production Competition Pro-style microswitch joystick with a nine-pin connector for classic computers.

AMIGAstore listed the Competition Pro Retro at EUR 32.75 but marked it out of stock with restock T.B.A. on 2026-07-30. The store still offers a stock-notification route. Do not substitute the currently available Competition Pro Extra without an adapter: that model uses USB-A for modern hosts rather than a classic nine-pin joystick plug.

Adds 512 KB of SRAM to an Amstrad CPC 6128 or CPC 6128 Plus through the Z80 CPU footprint.

The Lotharek page exposed a login-or-register-to-buy path on 2026-07-27. The CPU must be removed or desoldered, the module fitted in its place, and the CPU installed on the module. Confirm pin-1 orientation, socket quality, board clearance, and the computer's condition before beginning the invasive installation.

Converts the CPC 6128's internal 26-pin floppy connection to a standard 34-pin Shugart interface.

The Lotharek page exposed a login-or-register-to-buy path on 2026-07-27. Installation requires soldering the adapter in place of the original flat cable. A replacement drive or HxC emulator is not included, and the attached device still needs the correct configuration, power, mounting, and media setup.

Replaces the CPC 6128's six-pin video socket with a Mini-DIN 9 output wired to the Mega Drive 2 A/V standard.

Both the adapter-only and SCART-bundle pages exposed login-or-register-to-buy paths on 2026-07-27. Installation requires desoldering the original six-pin socket, soldering the adapter, connecting its 5 V wire, and wiring the AL and AR audio pads. The seller explicitly says not to remove the nearby resistors. Confirm pin orientation and display compatibility before applying power.

Builds a PET 4032-compatible mainboard from modular CS/A65 processor, PET I/O, and video cards.

No assembled seller or current PCB supplier was verified. A build needs three or four CS/A65 cards, a backplane, components, a programmed ROM, a case, a display or video-interface circuit, and a power supply. PETCPU revision 1.1B publishes board files but its layout is marked untested; the current VDC and PETIO pages publish later revisions marked okay, while the replica instructions date from 2010.

Builds a Commodore 1581-compatible IEC disk drive from CS/A65 processor and floppy-interface cards.

No assembled seller or current PCB supplier was verified. A build needs PETCPU and DRVIO cards, a backplane, components, a suitable 720 KB drive mechanism, a legal 1581 ROM image, power, cabling, and an enclosure. DRVIO revision 1.1A is marked okay and was tested with double-density PC drives; PETCPU revision 1.1B publishes board files but its layout is marked untested. High-density operation can overclock the WD1772 and is not the documented 1581 configuration.

Turns a C64 or C128 into a stand-alone SID synthesizer with keyboard performance, real-time controls, MIDI support, and optional six-voice stereo.

Protovision showed 12 orange Cynthcart 2.0.1 cartridges in stock at EUR 38 with a one- to two-week shipping estimate on 2026-07-28. The maker also publishes ROMs and source for personal use, but does not permit third-party cartridge sales. The project page labels 2.01 current while also listing a 2.0.2 source reorganization, so check the included ROM revision if that distinction matters.

Three-slot C64 and C128 cartridge-port expander with per-slot switching, a fuse, status LEDs, and reset.

AMI64 presented a current-priced listing on 2026-07-27. The seller explicitly excludes the Commodore 64 Ultimate and Ultimate 64. Cartridge combinations can still conflict electrically or in the memory map, so change connections only with power off and enable only known-compatible combinations.

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

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.

Connects a 20-pin IDC Apple II floppy cable to a compatible DB-19 disk port.

The vendor page showed six units in stock on 2026-07-24. This is a connector adapter, not a drive emulator or controller; verify the attached cable, controller, and drive are electrically compatible before use.

Adds a rear-panel DB9 joystick connector to an Apple II with an internal 16-pin game I/O socket.

Infinity Products marked the assembled adapter out of stock on 2026-07-24.

Adds battery-backed date and timekeeping to a compatible Apple IIc memory-expansion card.

The dClock was out of stock on 2026-07-24. It is not a standalone IIc card: installation requires a compatible RamExpress or Apple IIc memory-expansion board with the required DRAM socket.

Switches an Apple II F8 ROM socket between its normal Auto-Start Monitor and a licensed RAM diagnostic ROM.

The current Infinity Products page listed an assembled product without an out-of-stock marker on 2026-07-24. Personal-use fabrication files remain available under a noncommercial license; the Dead Test ROM has separate licensing terms.

DIY diagnostic ROM and loopback harness for PAL and NTSC Commodore 264-family computers.

Rob Clarke's current download directory offered Diag264 0.97 on 2026-07-30. The maker also offers a programmed EPROM at media and postage cost by email. The software is CC BY-NC-ND 4.0: unmodified personal distribution with attribution is allowed, but modification and commercial resale are prohibited. The maker warns that some third-party marketplace copies were unauthorized or modified. Loopback hardware may be resold when the attribution conditions are met.

An external fifteen-ROM selector for original Sinclair 48K, 128K, and grey +2 computers, controlled by one button and binary indicator LEDs.

The seller exposed a login-or-register-to-buy path on 2026-07-27 and explicitly limits support to original Sinclair 48K, 128K, and grey +2 machines. Power off before connecting or removing it. Confirm the exact ROM contents and any software licensing from the current unit rather than assuming every example named on the board is supplied or redistributable.

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

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.

Adds eight pushbutton inputs and eight LED outputs.

The current listing is a complete kit, with a bare PCB offered through the vendor's grouped PCB listing.

Replaces a Disk II drive's single red activity LED with separate green-read and red-write indication.

The current page exposed assembled and kit selectors with an Add to cart path on 2026-07-24. Host compatibility still depends on having a working Disk II drive, cable, and controller.

Adds CompactFlash storage, selectable disk firmware, an LCD, and a five-mode joystick interface to original ZX Spectrum computers.

Lotharek marks this revision discontinued. The seller says its joystick functions were tested on original Sinclair and Amstrad ZX Spectrum computers and does not guarantee clones. Media needs one active FAT16 partition, and compatibility still depends on selected firmware and correctly prepared software images. Identify the installed firmware and switch settings before using a second-hand unit.